scientificfinding.gau.ac.irscientificfinding.gau.ac.ir/uploading/scientificfinding... · 2013. 7. 21. · Iranian Journal of Weed Science Volume 5 Number 2 2009 Executive Director:

Iranian Journal of Weed Science Volume 5 Number 2 2009

Executive Director: Hamid Rahimian-Mashhadi, Agriculure & Natural Resoures, Tehran University

Chief Editor: Mohammad-Ali Baghestani, Iranian Research Institute of Plant Protection, Tehran

Editorial Board: Mohammad Abdolahian-Noghabi, Sugar Beet Seed Institute, Karaj. Hassan Alizadeh, Agriculure & Natural Resoures, Tehran University Jafar Asghari, Agriculture& Natural Resources, Gilan University

Hossein Ghadiri, Faculty of Agriculture, Shiraz University Hossein Mousavinia, Faculty of Agriculture, Chamran University, Ahvaz Mohammad-Hassan Rashed, Faculty of Agriculture, Ferdowsi University, Mashhad.

Reviewers: Majid Abbaspoor, Majid Aghaalikhani, Mohammad Bazoobandi, Mohsen Beheshtian, Javid Gherekhloo, Mohammad Hassan Hadizadeh, Hassan Karim Mojeni, Mohammad Reza Mousavi, Shahram Norozzadeh, Mostafa Ovisi, Naser Majnoon Hosseini, Mohammad-Hassan Rashed Mohasel, Rahim Mohammadian, Hossein Najafi, Noshin Nezamabadi, Mehdi Rastgoo, Parviz Shimi

Secretary: Mercedeh Taghavi, Iranian Research Institute of Plant Protection, Tehran ِ

Iranian Journal of Weed Science, as an official publication of Iranian Society of Weed Science, presents original research and reviews in the fields of weed science from a diversity of perspectives including topics in biology, ecology, physiology and management of weeds and herbicide aspects. The journal is published biannually, one volume per year. Manuscripts should be submitted directly to: Secretary of Iranian Journal of Weed Science, Plant Pest & Disease Research Institute, P.O. Box 1454, Tehran 19395, Iran. The instruction for providing paper is available at the end of this issue. Membership is $25 per year, which includes receipt of Iranian Journal of Weed Science. Application form is available on: http://www.isws.ir Subscription (institutionslibraries, etc.) to Iranian Journal of Weed Science is $30 per year, one volume per year of two issues. The order form must be sent to: Iranian Society of Weed Science, Plant Pest & Disease Research Institute, P.O. Box 1454, Tehran 19395, Iran; or By E-mail: [email protected] Payment should be made by bank transfer to: National Westminster Bank Plc, Market Place Branch, 13 Market Place, Reading RG1 2EP. Sort code: 60-17-21, Account No.: 54174163

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Table of Contents

Wild Barley (Hordeum spontaneum Koch) Seed Germination as Affected by Dry Storage Periods, Temperature Regimes and Glumellae Characteristics .................................................... 1

R. Hamidi, D. Mazaheri and H. Rahimian

Nitrification Inhibition Properties in Root Exudate s of Brachiaria humidicola Plants ............. 13

M. K. Souri and G. Neumann

Mouse Barley Germination Environmental Factors Influencing Germination of Mouse Barley (Hordeum murinum L.) in South Khorasan Province, Iran ............................................. 27

S. V. Eslami and F. Afghani

Corn and Soybean Intercropping Canopy Structure as Affected by Competition from Redroot Pigweed (Amaranthus retrofelxus L.) and Jimson Weed (Datura srtramonium L.) ....................................................................................................................................................... 39

M. Aghaalikhani, F. Zaefarian, E. Zand, H. Rahimian Mashhadi and M. Rezvani

Floristic Composition of Weed Community in Turfgrass Fields of Bajgah, Iran ...................... 55

S. Esmaili and H. Salehi

Ability of Adjuvants in Enhancing the Performance of Pinoxaden and Clodinafop Propargyl Herbicides Against Grass Weeds .................................................................................. 65

A. Mousavinik, E. Zand, M. A. Baghestani, R. Deihimfard, S. Soufizadeh, F. Ghezeli and A. Aliverdi

Effects of Row Spacing and Weed Control Duration on Yield, Yield Components and Oil Content of Canola ...................................................................................................................... 79

M. Radjabian, J. Asghari, S. M. R. Ehteshami and M. Rabiee

Timing of Velvetleaf Management in Soybean (Glycine Max (L) Merrill) ................................. 91

Z. Hatami, M. Nasser Latifi, H. Rezvani and E. Zeinali

Iranian Journal of Weed Science 5 (2009)

Wild Barley (Hordeum spontaneum

Dry Storage Periods, Temperature Regimes, and

R. Hamidi1Department of Agronomy, Faculty of Agriculture, Shiraz University, Shiraz, Iran,

Faculty of Agriculture, Tehran University, Karaj, Iran

(Received 12 May 2009; returned 10 February 2010; accepted 6 December 2010)

ABSTRACT

After dry storage, germination of newly harvested intact and

(Hordeum spontaneum Koch) were determined at 20

weeks whereas, naked seeds germinated and no significant differences between dry st

periods were observed for germination of these seeds. Cold stratification periods had no effect

on germination percentages of non

and maximum temperatures for germination of wild barley seeds were 5

respectively. Results showed that wild barley glumellae had either physical or chemical

effects on seeds germination because, all naked seeds germinated but when intact seeds were

rinsed in ethanol 70% and distilled water, the germination

respectively, which was lower than that

Keywords: Cold stratification;

glumellae.

* Corresponding author: E-mail: [email protected]

Iranian Journal of Weed Science 5 (2009) 1-12

Hordeum spontaneum Koch) Seed Germination as Affected by Dry Storage Periods, Temperature Regimes, and Glumellae Characteristics

R. Hamidi1*, D. Mazaheri2 and H. Rahimian2

Department of Agronomy, Faculty of Agriculture, Shiraz University, Shiraz, Iran, 2Department of Agronomy,

Faculty of Agriculture, Tehran University, Karaj, Iran


dry storage, germination of newly harvested intact and naked seeds of wild barley

Koch) were determined at 20◦ C. Intact seeds did not germinate after 8

weeks whereas, naked seeds germinated and no significant differences between dry st


on germination percentages of non-dormant seeds of wild barley. The minimum, optimum,

and maximum temperatures for germination of wild barley seeds were 5



rinsed in ethanol 70% and distilled water, the germination percentage were 0 and 54%,

respectively, which was lower than that of naked and intact seeds.

Cold stratification; Hordeum spontaneum; Wheat; Cardinal temperature;

mail: [email protected]

Koch) Seed Germination as Affected by Glumellae Characteristics

Department of Agronomy,

naked seeds of wild barley

. Intact seeds did not germinate after 8

weeks whereas, naked seeds germinated and no significant differences between dry storage


dormant seeds of wild barley. The minimum, optimum,

and maximum temperatures for germination of wild barley seeds were 5, 20, and 30 ◦C,



percentage were 0 and 54%,

; Wheat; Cardinal temperature;

2 Hamidi et al. (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Seed dormancy is a major adaptive trait in

weeds which facilitates the survival of

them and provides for resistance to

preharvest sprouting in members of

Poaceae family (Benech-Arnold et al.,

2000). In addition, the seeds of many weed

species can remain viable in the soil seed

bank because they possess some types of

inherent dormancy (Fenner & Thompson,

2005). The dormancy can further reassure

that the germination of seeds to occur only

at an appropriate time and space (Benech-

Arnold et al., 2000), and that is an

important reason why most weeds are

successful, though each individual will

experience a differential success

(Gutterman & Nevo, 1993).

There are several factors that have been

found to trigger germination or break the

seed dormancy including cold

stratification, dry storage and/or exposure

of dry seeds to elevated temperature,

leaching, scarification and treatments with

chemicals may be involved in breaking

dormancy (Bradbeer, 1994). The

conditions required to break dormancy

often vary among species, but also vary

within species or populations. (Alen &

Meyer, 1998).

Wild barley (H. spontaneum Koch) such as

wild wheat is one of the principal grain

plants on which Neolithic food production

in the Near East was founded. Wild barley

is the progenitor of cultivated barley and

this is indicated by its cross-compatibility,

full fertility and sporadic spontaneous

hybridization with other cultivars. The

high genetic diversity of wild barley makes

it as the best resources for improving the

narrowing genetic base of the cultivated

barleys (Nevo, 1997). Wild barley is an

annual, brittle, two-row diploid (2n=14),

and is predominantly self-pollinating

(Brown et al., 1978). Wild barley is

widespread in the Near East Fertile

Crescent and its population involves

abundant genetic variation against drought

and salinity while its highest resistant

genotype is significantly correlated with

the high stress environment and with the

highest genetic polymorphism (Nevo,

1992).

It has been founded that freshly harvested

seeds of wild barley do not germinate in a

range of temperatures, in light or darkness

(Gutterman & Nevo, 1993; Gutterman et

al., 1996). An important survival strategy

of wild barley under unpredictable small

amounts and infrequent winter rains in dry

regions is after-ripening (Evenari, 1965;

Gutterman, 1998). The need for after-

ripening prevents germination of mature

seeds after a late rain at the beginning of

the long, dry summer (Evenari, 1965). The

primary dormancy in wild barley seeds is a

result of glumellae, the seed covering

tissue. Such covering structures of the seed

may limit the oxygen supply to the embryo

(Gutterman, 1996) and thus inhibit

germination. Gutterman et al., (1996)

reported that the dormancy breaking of

wild barley seeds occur during storage in

dry conditions at 35 ◦C or in the natural

habitat during summer. Gozlan &

Gutterman, (1999) found that seeds of wild

Wild Barley (Hordeum spontaneum Koch) Seed Germination … 3

barley ecotypes that originating from

different regions, show different

germination responses to dry storage

temperatures and duration.

The aims of this investigation were to

study (1) the effect of constant

temperatures on seed germination, (2)

after-ripening patterns of wild barley

seeds, (3) effect of cold stratification on

seed germination, and (4) physical and

chemical effects of glumellae on seed

germination of wild barley.

MATERIALS AND METHODS

All experiments were conducted in

laboratory and germination tests were done

in dark condition. Caryopses of wild barley

were harvested on 15 May 2004 from the

Experimental Station Farm of Shiraz

University at Kushkak located 1650 meters

above the average sea level with a

longitude of 52° 34′ E and latitude of 30° 7′ N.

Experiment 1

Effect of Constant Temperatures on Wild Barley Non-Dormant Seed Germination

To determine the cardinal temperatures for

the germination of wild barley seeds

compared to wheat (Triticum aestivum cv.

Pishtaz), surfaced-sterilized wild barley

and wheat seeds were germinated in

sterilized 9-cm Petri dishes containing two

sheets of Whatman # 2 filter papers

moistened with 5 ml of distilled water.

Petri dishes were then placed at 8 constant

temperature regimes of 5, 10, 15, 20, 25,

30, 35, and 40 ◦C under dark condition.

Germination counts were made after 3 and

7 days. Germination was considered to

occur when radicle length was 1 mm or

longer.

Experiments were conducted in a

completely randomized design (CRD) with

four replications. Twenty five seeds in

each Petri dish were considered as a

replicate. Data were subjected to analysis

of variance procedure. Statistical analysis

of data was conducted using MSTAT-C

software.

Experiment 2

Effect of Dry Storage Periods on Germination of Wild Barley Seeds

Immediately after harvesting, the seeds

were stored in fine-mesh bags at room

temperature (25±3 ◦C) with relative

humidity ranging from 15-20%. At 7-day

intervals (for 14 weeks), two samples of

100 intact and hand dehulled (naked) seeds

(four replicates of 25 seeds) were selected

and germinated in a germinator set to

constant temperature of 20± 1 ◦C in the

darkness (based on results of experiment

1). For each experiment, seeds were placed

in 9-cm sterilized Petri dishes on two

sheets of Whatman #2 filter paper and

moistened with 5 ml of distilled water.

Germination was considered to occur when

radicle length was 1 mm or longer.

Experimental design was split factorial in

which the storage time was considered as

main plot and seed type was considered as

sub-plot.

Experiment 3

Effect of Cold Stratification on Dormant and Non-Dormant Seed Germination of Wild Barley


Wild barley dormant (freshly harvested)

and non-dormant (from the previous year)

seeds were placed in 9-cm sterilized Petri

dishes on 2 sheets of Whatman # 2 filter

paper and moistened with 5 ml distilled

water and stored in an incubator at constant

temperature of 2± 1 ◦C for 4 weeks. At 7-

day intervals, dishes were randomly

selected and transferred to germinators and

were kept at constant temperatures of 10,

20 and 40 ◦C in the dark condition for 7

days. After 7 days the germinated seeds

were counted. During cold stratification,

the dishes were checked to make sure the

seeds remain moist. Experiments were

conducted using a split-plot design with

four replicates. Twenty five seeds in each

Petri dish were considered as a replicate.

The main factor constituted three

temperature levels (10, 20 and 40 ◦C) and

the sub-factor constituted five stratification

periods of 0, 1, 2, 3 and 4 weeks at 2 ± 1 ◦C. No germination was occurred when the

dishes were incubated at 2± 1 ◦C.

Homogeneity were calculated for all of the

experiments (as variance) and those data

not linearly distributed were log10

transformed and detrains formed data are

present in the results. Data were subjected

to analysis of variance, and mean

separation was made using Duncan`s new

multiple range test at the 0.05 level of

significance.

Experiment 4

Effects of Glumellae Characteristics on Wild Barley and Wheat Seeds Germination

Germination of intact and dehulled wild

barley and wheat seeds were examined

under 13 conditions as described below:

1) Wild barley intact seeds (with

glumellae) in order to reveal the physical

effects of glumellae on germination;

2) Wild barley naked seeds along with the

separated glumellae in the Petri dish to

reveal the chemical effects of glumellae;

3) Wild barley intact seeds were rinsed in

ethanol 70% for 5 min to remove any

possible ethanol-soluble compound(s) from

the glumellae (Chen et al., 2004);

4) Wild barley intact seeds were rinsed in

distilled water for 5 min to remove any

possible water-soluble compound(s) from

the glumellae;

5) Wild barley naked seeds were rinsed in

ethanol 70% for 5 min;

6) Wild barley naked seeds were rinsed in

distilled water for 5 min;

7) Wild barley naked seeds alone;

8) Wild barley naked seeds and their

separated glumellae were rinsed in ethanol

70% for 5 min and were then placed in the

same Petri dishes;

9) Wheat seeds with wild barley glumellae

(25:25 in each Petri dish);

10) Wheat seeds with wild barley naked

seeds (25:25 in each Petri dish);

11) Wheat seeds with wild barley intact

seeds (25:25 in each Petri dish);

12) Wheat seeds with wild barley

glumellae that rinsed in 70% ethanol for 5

min (25:25 in each Petri dish);


13) Wheat seeds alone.

Following 7-days incubation at 25 ± 1oC,

seed germination, shoot and root length,

and number of seminal roots for both

plants were measured. Germination was

considered to occur when radicle length

was 1 mm or longer.

The experiment was conducted in a

completely randomized design (CRD) with

four replications. Homogeneity were

calculated for all of the experiments (as

variance) and those data not linearly

distributed were log10 transformed and

detransformed data are present in the

results.

RESULTS AND DISCUSSION

Experiment 1

Effects of Constant Temperatures on Wild Barley Seeds Germination

Wild barley seeds required temperatures

lower than 30 ◦C for germination.

Maximum germination occurred at 20 ◦C

(Figure 2). This optimum temperature for

wild barley seeds germination was similar

to that of reported by (Gutterman et al.,

1996).

Wheat seeds germinated nearly 100% after

7 days at 25 ◦C or lower temperature, but

declined to 24 and 0% at temperatures of

35 and 40 ◦C, respectively (Figure 3). The

rate of germination for wild barley seeds

was lower than that of wheat in both

counting dates (Figures 2 & 3). The wheat

also maintained a high germination

percentage at high temperature. Compared

to wheat, final germination values were

lower for wild barley at all temperatures.

The results of this study indicated that

lower temperatures (i.e. 5-10 ◦C) were

more favorable for germination of wild

barley seeds than higher ones (30-40 ◦C).

These results agree with the results of

(Egley & Duke, 1984) who reported that

high temperatures may denature the

enzymes and change lipid phase. However,

the lack of germination of wild barley

seeds at temperatures higher than 30 ◦C can

be due to lower temperature requirements

of this species for germination. However,

(Gozlan & Gutterman, 1999) reported that

after 20 months of storage of H.

spontaneum seeds at 10-30 ◦C, a negligible

percentage of seeds germinated at 30 ◦C.

Experiment 2

Effects of Dry Storage Periods on Wild Barley Seed Germination

No germination of intact seeds occurred

until 8 weeks after storage (Figure 1). All

these seeds were found to be dormant, as

shown for Aegilops cylindrica (Fandrich &

Mallory-Smith, 2005), Tripsacum

dactyloides (Gibson et al., 2005) and

Phalaris sp. (Matus-Cadiz & Hucl, 2005).

The germination of intact seeds increased

with dry storage durations. After 12 weeks,

the germination of intact seeds reached its

maximum rate (65%). This delay in

germination, usually called after-ripening,

is an important survival strategy for many

Poacea family members such as Lolium

rigidum (Steadman et al., 2003), weedy

rice (Oryza sativa) (Gu et al., 2005), and

Alopecurus myosuroides (Colbach & Durr,

2003) which may confront unpredictable

rainfall in the summer (Evenari, 1965). On

the contrary, no significant differences


between dry storage periods were observed

for naked seeds germination (Figure 1).

The dormancy of wild barley freshly

harvested seeds results mainly from

inhibitory action of glumellae which is

reduced during dry storage (Figure 1).

It was suggested by (Lenior et al.,

1986) that in wild and cultivated barley

(Hordeum vulgare L.) glumellae prevents

germination by placing the seed in

hypoxia, because they fix oxygen.

However, a good oxygen supply under the

glumellae would be necessary only during

the first hours of germination. In fact, after

30 hour, oxygen uptake by the glumellae is

the same for dormant and non-dormant

seeds. This oxygen absorption would be

sufficient to prevent germination of freshly

harvested seeds. But, after a long period of

dry storage, seeds would not be subjected

to this inhibition action because

germination would have started at the

beginning of imbibition, when the

glumellae absorb very little oxygen.

However, primary dormancy of H.

spontaneum is much deeper than that of

seeds of cultivated barley. According to

(Baker, 1974), the success of a weed may

depend in part on a delay in germination

until conditions are suitable for plant

growth therefore, high wild barley

population density in wheat fields can be

attributed to this phenomenon.

Experiment 3

Effects of Stratification Periods on Wild Barley Dormant and Non-Dormant Seed Germination

No significant differences were observed

among stratification periods at all

temperature regimes, whereas, the mean

germination percentages varied

significantly between temperature regimes.

Overall, the highest germination

percentage was occurred at 20 ◦C (87%)

followed by 10 ◦C (65%) with no

germination at 40 ◦C (Table 1). None of the

dormant seeds germinated after 4 weeks

(data not shown), indicating those four

weeks of cold stratification could not

alleviate the dormancy of wild barley

seeds. Baskin & Baskin, (1998) reported

that cold stratification is not required for

seed germination of all species, but is

required for embryo growth in seeds with

non-deep dormancy. Since, the dormancy

of wild barley seeds is more likely to be

related to glumellae characteristics (Figure

1) and not to embryo, this may explain

why cold stratification is not effective for

dormancy breaking.


Table 1. Effects of cold stratification periods on germination of wild barley non-dormant caryopsesab. Constant Weeks of stratification at 2 1 ± °C temperature 0 1 2 3 4 Means (°C) %

10 66.00 a 66.00 a 65.00 a 64.00 a 66.00 a 65.40 B 20 87.00 a 86.00 a 88.00 a 87.00 a 87.00 a 87.00 A 40 0.00 a 0.00 a 0.00 a 0.00 a 0.00 a 0.00 C

Means 51.00 a 50.66 a 51.00 a 50.33 a 51.00 a aMeans within each row with the same letters (small letters) are not significantly different at

the 5% level according to Duncan's new multiple range test. bMeans within each column with the same letters (capital letters) are not significantly different

at the 5% level according to Duncan's new multiple range test.

Figure 1. Effects of dry storage periods on germination of wild barley intact and naked seeds at 20 ◦ C

.

Experiment 4

Effect of Glumellae Characteristics on Wild Barley and Wheat Seed Germination

The effects of different treatments on wild

barley intact and naked seeds germination

and the seedling growth are shown in

Table 2 Only 59% of intact seeds were

able to germinate within 7 days of

incubation (T1). When the glumellae was

removed, the naked seeds germinated up to

100% (T7). Naked seeds placed adjacent to

glumellae germinated 95% (T2). Very

similar results were obtained with naked

seeds and detached glumellae that were

inserted in ethanol 70% for 5 min (T8).

Intact seeds treated with ethanol (T3) did

not germinate but, those inserted in

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14

Dry storage periods after harvest (weeks)

Ger

min

atio

n (%

)

Naked caryopses

Intact caryopses


distilled water (T4) had germinated as

great as 54%. The germination percentages

of naked seeds that were treated with

ethanol (T5) or distilled water (T6) were

90 and 95%, respectively (Table 2).

Shoot length of intact seeds that were

treated with distilled water (T4) were 54

mm and less than that showed no

differences (T1), whereas, root length, and

number of seminal roots were not affected

by all treatments (Table 2). Wheat seed

germination, root length, and number of

seminal roots were not influenced by any

of the treatments (Table 2), but the shoot

length was increased as affected by wild

barley glumellae.

The results presented above clearly show

that glumellae had either physical and

chemical effects on wild barley seed

germination. When intact seeds were

rinsed in ethanol 70% (T3) and distilled

water (T4), their germination percentages

were 0 and 54%, respectively. This was

lower than that of naked (T7) and intact

seeds (T1). This may be the main reason

for chemical stimulating effects of

glumellae on germination. The presence of

some phenolic compounds in seeds of

Graminae family has been reported

(Belderock, 1961; Glennie, 1981;

Jayachandran-Neir & Sridhar, 1975). In

nature and under high interference

pressure, there are many known and

unknown mechanisms that may be

involved in enhancing the seed

germination and plant seedling

establishment. Results from this study

show that ethanol- and/or water-soluble

compound exist in glumellae and are

desirable and suitable to enhance seed

germination and seedling growth of its

own plant. In this relation, absence of the

glumellae chemical compound (T3 and T4)

decreased germination of seeds (Table 2).

Hamidi et al., (2006) reported that some

extract concentrations made from the intact

seeds of wild barley stimulated

germination, shoot and root lengths, shoot

and root dry weights of wheat and its own

plant and this phenomenon could be

considered as an ecological adaptation.


Table 2. Effects of physical and chemical characteristics of wild barley glumellae on wheat seed and its own

seed germination, shoot and root length, and number of seminal roots a,b.

Growth parameters Treatments Germination Shoot length Root length Seminal roots

(%) (mm) (mm) (no.) Wild barley

T1 59 b 94.43 ab 116.00 a 3.16 a

T2 95 a 99.43 a 104.40 a 3.42 a

T3 0 c 0 c 0 b 0 b

T4 54 b 54.17 b 93.17 a 3.16 a

T5 90 a 106.30 a 119.30 a 3.32 a

T6 95 a 82.65 ab 113.60 a 3.10 a

T7 100 a 85.87 ab 109.40 a 3.66 a

T8 99 a 87.33 ab 111.00 a 3.33 a Wheat

T9 100 a 129.50 a 123.70 a 5.81 a

T10 99 a 108.20 b 114.00 a 5.71 a

T11 99 a 106.50 b 123.40 a 5.63 a

T12 100 a 121.70 a 129.40 a 5.22 a

T13 100 a 112.70 b 126.30 a 5.07 a aFor each species, means within each column with the same letters are not significantly different at the 5% level according to Duncan`s new multiple range test. bT1: intact seeds; T2: naked seeds with the glumellae; T3: intact seeds treated with 70% ethanol; T4: intact seeds treated with distilled water; T5: naked seeds treated with 70% ethanol; T6: naked caryopse treated with distilled water; T7: naked seeds; T8: naked seeds with the gelumellae treated with 70% ethanol; T9: wheat seeds with wild barley gelumellae; T10: wheat seeds with naked seeds; T11: wheat seeds with intact seeds; T12: wheat seeds with glumellae that treated with 70% ethanol; and T13: wheat seeds.

Figure 2. Effects of constant temperatures on wild barley seeds germination after 3 and 7 days.

: y = -0.2049x2 + 7.53x R2 = 0.6436

: y = -0.2346x2 + 8.66x R2 = 0.6784

0

20

40

60

80

100

0 5 10 15 20 25 30 35 40

Temperature (C)

Ger

min

atio

n (%

)

3 days

7 days


Figure 3. Effects of constant temperatures on wheat seed germination after 3 and 7 days.

REFERENCES

Baker, H. G. 1974. The Evolution of Weeds.

Annual Review of Ecological Systems 5: 1-24.

Baskin, C. C. and Baskin, J. M. 1998. Seeds:

Ecology, Biogeography, and Evolution of

Dormancy and Germination. Academic Press,

666 pp.

Belderock, B. 1961. Studies on dormancy in wheat.

Proceeding of International Seed Testing

Associated 26: 697-760.

Benech-Arnold, R. L., Sanches, R. A., Forcella, F.,

Kruk, B. C. and Chesa, C. M. 2000.

Environmental control of dormancy in weed

seed banks. Field Crop Research. 67: 105-

122.

Bradbeer, J. W. 1994. Seed Dormancy and

Germination. Ipswich Book Company Ltd,

Ipswich, 146 pp.

Brown, A. H. D., Nevo, E., Zohary, D. and Dagan,

O. 1978. Genetic variation in natural

populations of wild barley (Hordeum

spontaneum). Genetica 49: 97-108.

Chen, G., Tamar, K. Fahima, T., Zhang, F., Korol,

A. B. and Nevo, E. 2004. Differential patterns

of germination tolerance of mesic and xeric

wild barley (Hordeum spontaneum) in Israel.

Journal of Arid Environment 56: 95-105.

Colbach, N. and Durr, C. 2003. Effects of seed

production and storage conditions on

blackgrass (Alopecurus myosuroides)

germination and shoot elongation. Weed

Science 51: 708-717.

Egley, G. H. and Duke, S. O. 1984. Physiology of

weed seed dormancy and germination. pp. 27-

64, In: S. O. Duke (ed.). Weed Physiology.

Vol. 1. Reproduction and Ecophysiology. CRC

Press, Inc., Boka Raton, Fl.

Evenari, M. 1965. Physiology of seed dormancy,

after-ripening and germination. Proceeding of

International Seed Testing Associated 30: 49-

71.

Fandrich, L. and Mallory-Smith, C. 2005.

Temperature effects on jointed goat grass

(Aegilops cylindrica) seed germination. Weed

Science 53: 594-599.

Fennre, M. and K. Thompson. 2005. The Ecology

of Seeds. Cambridge University Press,

Cambridge, UK, 252 pp.

Gibson, L. R., Albert, E. Z., Knapp, A. D., Moore,

K. J. and Hintz, R. 2005. Release of seed

dormancy in field plantings of gamagrass.

Crop Science 45: 494-502.

Glennie, C. W. 1981. Preharvest changes in

polyphenols peroxidase, and polyphenols

: y = -0.2826x2 + 10.96x R2 = 0.8908

: y = -0.2951x2 + 11.47x R2 = 0.7873

0

20

40

60

80

100

0 5 10 15 20 25 30 35 40

Temperature (C)

Ger

min

atio

n (

%)

3 days

7 days


oxidase in sorghum grain. Journal of

Agriculture and Food Chemistry 29: 33-36.

Gozlan, S. and Gutterman, Y. 1999. Dry storage

temperatures, duration, and salt concentrations

affect germination of local and edaphic

ecotypes of Hordeum spontaneum (Poaceae)

from Israel. Biological Journal of Linnean

Society 67: 163-180.

Gu, Xing-You, S., Kianian, F. and Foley, M. E.

2005. Seed dormancy imposed by covering

tissues interrelates to shuttering and seed

morphological characteristics in weedy rice.

Crop Science. 45: 948-955.

Gutterman, Y. 1996. Temperatures during storage,

light and wetting affecting seeds germinability

of Schismus arabicus a common desert annual

grass. Journal of Arid Environment 33: 73-85.

Gutterman, Y. 1998. Ecological strategies of desert

annual plants. pp. 203-231, In: R. S. Ambasht

(ed.), Modern Trends in Ecology and

Environment. Backhuys, Leiden, 362 pp.

Gutterman, Y. and Nevo, E. 1993. Germination

comparison study of Hordeum spontaneum

regionally and locally in Israel: A population

in the Negev Desert Highlands and from two

opposing slopes on Mediterranean Mount

Carmel. Barley Genetics Newsletter 22: 65-71.

Gutterman, Y., Corbineau, F. and Come, D. 1996.

Dormancy of Hordeum spontaneum seeds

from a population on the Negev Desert

Highlands. Journal of Arid Environment 33: 337-345.

Hamidi, R., Mazaheri, D., Rahimian, H., Alizadeh,

H. M., Ghadiri, H. and Zeinaly, H. 2006.

Inhibitory effects of wild barley (Hordeum

spontaneum Koch.) residues on germination

and seedling growth of wheat (Triticum

aestivum L.) and its own plant. Desert 11: 35-

43.

Jayachandran-Nair, K. and Sridhar, R. 1975.

Phenolic compounds in rice husk. Biological

Plant. 17: 318-319.

Lenior, C., Corbineau, F. and Come, D. 1986.

Barley (Hordeum vulgare) seed dormancy as

related to glumellae characteristics.

Physiological Plantarum. 68: 301-307.

Matus-Cadiz, M. A. and Hucl, P. 2005. Rapid

effective germination methods for overcoming

seed dormancy in annual canarygrass. Crop

Science. 45: 1696-1703.

Nevo, E. 1992. Origin, evolution, population

genetics and resources for breeding of wild

barley, Hordeum spontaneum, in the Fertile

Crescent. Pp. 19-34. In: P. R. Shewry (ed.),

Barley Genetics, Biochemistry, Molecular

Biology and Biotechnology. CAB Int.

Wallingford, UK.

Nevo, E. 1997. Evolution in action across

phylogeny caused by microclimatic stresses at

"Evolution Canyon". Theoretical Population

Biology 52: 231-243.

Steadman, K. J., Bignell, G. P. and Ellery, A. J.

2003. Field assessment of thermal after-

ripening time for dormancy release prediction

in Lolium rigidum seeds. Weed Research 43: 458-465.


دهيچك

جوانه ند وليگندمه هاي دست نخورده تا هشت هفته جوانه نزد. گرديد تعييندرجه سانتي گراد 20هاي تازه رسيده جو وحشي در دمايگندمه جوانه زني

تفاوت معني داري وجود آنهاجوانه زني و در آغازجوانه زني گندمه هاي پوست كنده از هفته اول . هفته به بيشترين مقدار رسيد 12پس از آنهازني

گندمه هاي تازه .ميباشندفيزيكي جوانه زني مانعگندمه هاي دست نخورده از نوع پس رسي بوده و پوشينه ها خواب نتايج نشان دادند كه . نداشت

ن درصد جوانه زني يانگيم. درجه سانتي گراد براي چهار هفته نگهداري شدند 2±1كه دوره پس رسي را گذرانيده بودند در دماي آنهاييو رداشت شدهب

گونه تفاوت چيهفته، ه 4و 3، 2پس از . و صفر درصد بود 86، 66 يبگراد براي گندمه هاي بدون خواب به ترتيدرجه سانت 40و 20، 10در دماهاي

كدام از گندمه هاي تازه برداشت شده چيه. ط سرمادهي بودند، مشاهده نشديهفته در شرا 4و 3، 2 ،1ي كهين درصد جوانه زني گندمه هايمعني داري ب

درجه 40، و 35، 30، 25، 20، 15، 10، 5جوانه زني گندمه هاي بدون خواب جو وحشي و گندم در دماهاي ثابت . جوانه نزدند ،هفته سرمادهي 4پس از

در حالي كه رخ داد درجه سانتي گراد 20ن درصد جوانه زني گندمه هاي جو وحشي در دماي ثابت يشتريروز، ب 7پس از . ري شديسانتي گراد اندازه گ

درجه سانتي گراد جوانه زده و در 30تا 5گندمه هاي جو وحشي در دامنه . جوانه زدند ا كمتريدرجه سانتي گراد و 25ي گندم در دماي درصد بذرها 100

، نه هاي جو وحشي روي جوانه زني خود و گندميي پوشيايميكي و شيزين اثر فييبه منظور تع .بودند سه با گندم از سرعت جوانه زني كمتري برخورداريمقا

شه هاي بذري يساقه چه و تعداد ر شه چه وي، درصد جوانه زني، بلندي ر20±1 روز و در دماي ثابت 7ش قرار گرفته و پس از يمار مورد آزمايزده تيس

.دارندمهمي نقش جو وحشي بذر كي براي جوانه زنييزيف بازدارندهك ينه ها به عنوان يج نشان دادند كه پوشينتا. ري شدندياندازه گ

فراشدهي سرمائي، جودره، گندم، دماي پايه، پوشينه: كليديكلمات


Nitrification Inhibition Properties in Root Exudate s of

1* Department of Horticultural Sciences, Tarbiat Modares University, Tehran2 Institute of Plant Nutrition, University of Hohenheim, Stuttgart


ABSTRACT

Nitrification inhibition (NI) by climax ecosystems has been suggested for decades, and this

inhibitory effect seems to be a feature of wild genotypes rather than commercial cultivars.

Many plants particularly grasses were suggested to have NI activity, and

humidicola (BH) was shown to have promising control on nitrification rates through root

exudates. In this study effects of different treatments such as N form (NH

concentrations (1, 2 and 4 mM N), plant age, light inte

for root exudates on the NI activity of root washings were investigated. This was done using a

series of nutrient solution experiments. The results showed that BH root exudates collected in

distilled water, independent of light intensity, plant age, N

exudates collection periods, had no significant inhibition on nitrification. However, root

exudates collected in a 1 mM NH

process in a soil bioassay. This inhibition was more highlighted when plants were grown in

presence of ammonium rather than nitrate. In comparison to drying with rotary evaporator,

freezed dried root exudates indicated significant NI in root exudates of plants which

grown in NH4+ under low light, while this effect was not seen under higher light intensity or

nitrate nutrition. Measuring electric conductivity of solutions from root washing also showed

higher conductivity when ammonium presented in root medium, par

collecting medium over extended time (24 instead 6 hours).

Keywords: root exudates, ammonium, nitrate, electric conductivity



Nitrification Inhibition Properties in Root Exudate s of Brachiaria

humidicola Plants

M. K. Souri1*,G. Neumann 2

Department of Horticultural Sciences, Tarbiat Modares University, Tehran

Institute of Plant Nutrition, University of Hohenheim, Stuttgart-Germany




Many plants particularly grasses were suggested to have NI activity, and recently

(BH) was shown to have promising control on nitrification rates through root

exudates. In this study effects of different treatments such as N form (NH

concentrations (1, 2 and 4 mM N), plant age, light intensity and different collecting mediums



t of light intensity, plant age, N-forms, N-concentrations and root


exudates collected in a 1 mM NH4Cl medium had significant inhibition on nitrification

soil bioassay. This inhibition was more highlighted when plants were grown in


freezed dried root exudates indicated significant NI in root exudates of plants which

under low light, while this effect was not seen under higher light intensity or


higher conductivity when ammonium presented in root medium, particularly in root exudates

collecting medium over extended time (24 instead 6 hours).

root exudates, ammonium, nitrate, electric conductivity

[email protected]

Brachiaria

Department of Horticultural Sciences, Tarbiat Modares University, Tehran- Iran

Germany



recently Brachiaria

(BH) was shown to have promising control on nitrification rates through root

exudates. In this study effects of different treatments such as N form (NH4+ vs NO3

-) and N

nsity and different collecting mediums



concentrations and root


Cl medium had significant inhibition on nitrification

soil bioassay. This inhibition was more highlighted when plants were grown in


freezed dried root exudates indicated significant NI in root exudates of plants which were

under low light, while this effect was not seen under higher light intensity or


ticularly in root exudates

14 Souri and Neumann (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Nitrogen management requires sufficient

knowledge regarding spatial distribution of

mineral nitrogen. Nitrification is the main

cause of nitrogen losses in soil profile.

This process can be retarded by different

synthetic inhibitors. However, if plants

could manage nitrification, it would offer

important economic and environmental

implications. Identification of such plants

and related physiological and molecular

traits can help to introduce such highly

valuable properties from wild plants to

crops. This consequently could lead to less

application of fertilizers and higher N

recovery rates (Subarrao et al., 2006).

Plants are immobile in nature, but they

have the ability to apply different strategies

to coupe with unfavourable conditions

surrounding them, and to optimize

unfriendly conditions for their growth and

development. Despite physiological and

morphological changes, exudation of

primary and secondary metabolites by

roots as well as emission of chemicals

through leaves is a well known phenomena

in this case (Liljeroth & Baath, 1988; Jones

et al., 2004).

Brachiaria humidicola Napper plants are

C4 species and among the most important

pastures widely adapted to grow in tropical

and subtropical parts of South America,

Africa & Asia (CIAT, 1983). Different

Brachiaria species consist 85% of the total

planted pasture area in South America

(Nakamura et al., 2005), and commercially

an important economic player in the

tropics, particularly in Brazil. The genus

Brachiaria contains a wide range of

species, which are adapted to poor acid

soils and tolerant to drought and harsh

environments. Vast diversity in Brachiaria

plants could be the main reason of their

adaptation capacity to different edaphic

and climatic conditions. In comparison to

other plants, in such conditions, they have

relatively higher biomass production due to

the ability to uptake and use nutrients more

efficiently in poor soils (Nakamura et al.,

2005; Cazetta & Villela, 2004). There is no

report of growing such plants in Iran,

however they can be introduced to

subtropical parts in Southern provinces.

Observations during field surveys have

shown that soils of BH generally have low

levels of N-NO3- (CIAT, 1985; Sylvester-

Bradley et al., 1988). Recently

experiments show that root exudates of

Brachiaria plants specially BH (accession

26159) can efficiently suppress

nitrification process in laboratory, soil and

field conditions (Ishikawa et al., 2003;

Wang et al., 2005; Subbarao et al., 2005 &

2008). They indicated that only BH

particularly accession 26159 suppresses

nitrification in soil, and this inhibition

occurs under NH4+ rather than NO3

-

nutrition. Nevertheless, it has been

suggested that nitrification inhibition

abilities are a plant's specific reaction to

stress conditions, especially under low N

level in the soil (Ishikawa et al., 2003;

Subbarao et al., 2006).

(Subbarao et al., 2005, 2006 & 2007 a,b,c)

mentioned strong inhibition of collected

root exudates of BH on nitrification, which

this inhibitory effect was lasting up to 70

days, which is more efficient than synthetic

NIs such as N-Serve or DMPP (3,4-

Nitrification Inhibition Properties in Root … 15

dimethylpyrazol phosphate). Despite

recent works, there is still not enough

knowledge on nitrification inhibitory effect

of plants root exudates. Therefore, the

biological inhibition of nitrification by

crop plants or pasture species particularly

by BH plants is not well known, and still

many questions are to be answered. In

order to investigate whether the inhibitory

effect of root exudates would change

under different growth and physiological

conditions (N-form, N-concentrations,

different light intensities, plant age,

differing collecting medium and collecting

periods of root exudates), this study was

conducted using BH plants under

controlled condition in growth chamber.


Plant Culture

This study was conducted during 2005-

2007 in the Institute of Plant Nutrition,

University of Hohenheim, Stuttgart-

Germany. Seeds of Brachiaria humidicola

(Rendle) accession 26159 germinated at 25

ºC in fine sand (0.02-0.5 mm) for the first

experiment. For the next experiments, due

to long germination period (4 weeks),

heterogeneous germination, as well as low

germination rate (15%), vegetative new

tillers from older plants were used as new

seedlings. Seedlings more than 10 cm (3-4

leaves) were cut and transferred to

treatment condition in nutrient solution

(2.5 litres in black plastic pots). The

composition of nutrient solution was 10

µM H3BO3, 0.5 µM MnSO4, 0.5 µM

ZnSO4, 0.1 µM CuSO4, 0.01 µM

Mo7O24(NH4)6, 83 µM Fe-EDTA, 0.7 mM

K2SO4, 0.5 mM KH2PO4, 1.2 mM MgSO4,

1.2mM KCl. For ammonium treatments 1

mM CaCl2 was used (Souri, 2008).

Treatments were N-form (NH4+ or NO3

-) in

form of (NH4)2SO4 or Ca(NO3)2, with 1, 2,

and 4 mM N, depending on experimental

set up. However, normal N concentration

was 2 mM N as ammonium sulphate or

calcium nitrate. Each treatment consisted

of four replicates. Ammonium treatment

was applied either at the beginning of

transferring the seedlings to nutrient

solution or for short periods, after being

pretreated in nitrate (2 mM N-NO3- as pre-

culture) for two weeks (Prof. Dr. Volker

Römheld, personal communication).

In addition to N status, the effect of

different variable factors such as light

intensity and plant age (young three-

weeks-old vs seven-weeks-old plants) on

production and release of NIs were tested.

Different light intensity conditions were

applied using the same growth chamber, in

which for high light intensity (400

µmol/m2s-1), plants were placed at the

centre of the table in the growth chamber

with constant light intensity. For

intermediate light intensity plants were

placed at the corner of the growth

chamber, where light intensity was 240

µmol/m2s-1. Low light intensity was

achieved in the same growth chamber by

locating plants inside a box and under

different layers of plastic, where they

received 180 µmol/m2s-1 light intensity.

Plants were grown under a light/dark

regime of 16/8, and a temperature of 28/25

ºC in nutrient solution culture. Nutrient

solutions were renewed thoroughly every 3

days. In treatments with pH control, a

solution of 3 mM


Morpholinoethanesulfonic acid (MES) and

double daily pH checking and adjusting

with KOH, Ca(OH)2 and H2SO4 were

performed.

Collection of Root Exudates

Root exudates were collected 2 hours after

starting the light period, either for 6 hours

from 10 am to 4 pm, or for 24 hours from

10 am to 10 am in the next day. Before

collection, plant roots were washed for 1-2

minutes in distilled water. Collecting

medium generally was 500 ml distilled

water, however, a solution of 1mM NH4Cl

was also used as the collection medium.

After collection, root exudates were

concentrated at 35 ºC using rotary

evaporator to a volume of 15 ml, from

which 2.5 ml was applied per replicate in

soil incubation bioassay for rapid detection

of potential nitrification (Kandeler, 1993).

Four samples (replicates) for incubation as

well as two samples which were kept under

freezing conditions for original NO2-

concentrations were used to determine

potential nitrification inhibitory of root

exudates. In this study we used two

controls in our bioassay; first water control

in which distilled water was applied

instead of root exudates in soil nitrification

bioassay, and second 3,4 dimethylpyrazol

phosphate (DMPP) control as a standard

synthetic nitrification inhibitor which was

used in 10 times of its normal

concentration (1% of N-NH4) in all

incubations during this study. Plants were

exposed to 6 or 24 hours root exudates

collection in 1 mM NH4Cl, and the electric

conductivity (µS/m) of root washings after

3 hours collection was determined.

Excel and SPSS soft wares were used to

draw and analysis the data. Comparison of

means was performed at P= 0.05 using

Duncan test. In figures data are presented

as average of four replicates ± SD.

RESULTS

A) Collecting Root Exudates in Distilled Water

Root exudates of plants which were grown

in nutrient solution under NO3- and NH4

+

or under NH4+ but with buffered pH 6

(Figure 1), and were collected after a 24

hours period in distilled water, showed no

significant nitrification inhibition (NI)

compared to control. Significant changes

in the pH of nutrient solution were

occurred for both ammonium and nitrate

grown plants within only 24 hours where a

pH of 2 has been also recorded (data not

presented). Similarly, different effects of

plant age (Figure 2); collecting periods

(Figure 3); nitrogen concentrations (Figure

4); different light intensities (Figure 5),

when collected in distilled water, showed

no significant nitrification inhibition

compared to water or DMPP control.

DMPP, as a standard synthetic nitrification

inhibitor, always resulted in very low

amounts of produced nitrite in all

nitrification incubation tests, indicating

high efficiency regarding control of

nitrification (Figures 1-7).

Collected root exudates in distilled water

when dried in freeze drier and extracted

with methanol and further with DMSO

(Figure 6), showed significant NI activity

only in NH4+ grown plants under low light

intensity but not in nitrate or higher light

intensities. Nevertheless, there was a


general trend of nitrification reduction with

younger plants rather than older plants,

lower light intensities rather than higher, as

well as lower concentrations of nitrogen in

nutrient solution.

Figure 1. Nitrification inhibition effect of root exudates collected in 0.5 l distilled water for 24 hours period.

Plants were grown with NH4+, NO3

-, or buffered-NH4+, with the concentration of 2 mM N. PH of collected root

exudates was ~ 3.5 for NH4+ and ~ 7 for NO3

- grown plants. Data are average of four replicates ± SD.

Figure 2. Nitrification inhibition effect of root exudates of 3-weeks old (A) and 7-weeks old (B) plants grown

under 2 mM N-NO3- or NH4

+. The pH of nutrient solution for both ammonium and nitrate medium was adjusted

to 5 using MES and H2SO4 or KOH. PH of medium after collection was ~ 3.5 for NH4+ and ~ 7 for NO3

- treated

plants. Data are average of four replicates ± SD.

0

0,2

0,4

0,6

0,8

1

Water control DMPP NO3treated plants

NH4treated plants (pH 3(

NH4treated plants (pH6(

Nitr

ite (

mg/

100

g so

il)

A

0

0,2

0,4

0,6

0,8

1

1,2

Water control DMPP NO3-fed plants NH4-fed plants

Nitr

ite (

mg/

100

gr d

ry s

oil)

0

0,2

0,4

0,6

0,8

1

Water control DMPP NO3-fed plants NH4-fed plants

Nitr

ite (

mg/

100

g dr

y so

il)

B


Figure 3. Nitrification inhibition effect of root exudates collected in distilled water for 6 or 24 hours. Plants were

grown in nutrient solution with ammonium or nitrate (without pH adjustment during growing period). PH of

medium after collection was ~ 3.5 for NH4+ and ~ 7 for NO3

- plants. Data are the average of four replicates ± SD.

Figure 4. Nitrification inhibition of root exudates collected for 24 hours in distilled water. Plants were grown

with different N concentrations as NO3- or NH4

+. PH of collected root exudates was ~ 3.5 for NH4+ and ~ 7 for

NO3- plants. Data are average of four replicates ± SD.

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

Water control

DMPP NO3 24 h NO3 6 h NH4 24 h NH4 6 h

Nitr

ite (

mg/

100

g dr

y so

il)

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

Water control

DMPP NO3 1mM NO3 2mM NO3 4mM NH4 1mM NH4 2mM NH4 4mM

Nitr

ite (

mg/

100

g dr

y so

il)


Figure 5. Nitrification inhibition of root exudates collected in distilled water of 6 hours period (A) or 24 hours

period (B). Plants were grown in low (LL), middle (ML) and high (HL) light intensities with NH4+ (2 mM N),

compared to NO3- (2 mM N) grown plants in high light intensity. Data are average of four replicates ± SD.

Figure 6. Nitrification inhibitory effects of freeze dried root exudates (collected in distilled water) of plants pre-

treated with NH4+ or NO3

- in high or low light intensity, which have been extracted finally with 0.6% DMSO (on

basis of final volume). Data are average of four replicates ±SD. Duncan test was conducted for mean values at

P= 0.05.

6 h collection

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Water Control

DMPP NO3HL NH4HL NH4ML NH4LL

Nitr

ite (

mg/

100

g dr

y so

il) A

24 h collection

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

Water Control

DMPP NO3HL NH4HL NH4ML NH4LL

Nitr

ite (

mg/

100

g dr

y so

il)

B

a

ab b ab

a

0

0,1

0,2

0,3

0,4

0,5

0,6

Water control

DMSO control

NH4LL NH4HL NO3HL

Nitr

ite (

mg/

100

g dr

y so

il)


B) Collecting Root Exudates in NH4Cl Medium

Effects of collected root exudates in 500

ml of 1 mM NH4Cl solution for plants

grown in NH4+ or NO3

- under different

collecting periods are presented in (Figure

7). Significant inhibition of nitrification

compared to control was seen for NH4+

grown plants, although this was for the 24

hours collection period rather than the 6

hours collection period. There was no

significant inhibitory effect for nitrate

grown plants. However, root exudates of

nitrate grown plants showed considerable

inhibition after the 24 hours collection

period, which was not statically significant.

Electric conductivity (EC) of root

washings (Figure 8) showed higher

conductivity when ammonium is presents

particularly in the collecting medium.

Ammonium grown plants showed higher

conductivity rather than nitrate grown

plants.

Discussion

It is almost three decades that the role of

phytosidrophores has been well established

mainly in iron uptake of plants. Their

collection procedure is still used for

collecting root exudates for different

purposes. In these experiments, plant roots

were transferred 2 hours after the light

period to a distilled water medium for

collection of root exudates (Römheld &

Marschner 1986). In contrast to (Subbarao

et al., 2005, 2006a & 2007a) which

collected root exudates only in 1 mM

NH4Cl or KNO3, in this study we used

both 1 mM NH4Cl (or KNO3), and distilled

water as the collecting medium for root

exudates. In Figures 1-6, root exudates

collected in distilled water from plants

grown under different N forms, N

concentrations in nutrient solution, plant

age, light intensities, as well as collecting

periods showed no significant inhibitory

effect on nitrification. However, root

exudates of ammonium grown plants under

low light intensity which were collected in

distilled water and dried using freeze drier

instead of rotary evaporator, showed

significance differences compared to

control (Figure 6). This might be due to

avoiding some degradation of NI

compounds during routine concentration

procedure via rotary evaporator. This, in

turn, indicates that the release procedure of

natural nitrification inhibitors (NNIs) may

not be an active process, since collecting in

distilled water due to the osmotic effect,

results in higher exudation (Neumann &

Römheld, 2000). Exposure of plant roots to

external solutions of very low ionic

strength is likely to increase exudation

rates due to an increased transmembrane

concentration gradient of solutes

(Neumann & Römheld, 2000). The highest

inhibitory effect occurred when 1 mM

NH4Cl was used in the collecting medium

(Figure 7). This inhibition was a function

of the collection period and N-form.

Similar results were obtained by others

(Subbarao et al., 2005-2008; Ishikawa et

al., 1999; 2003; Gopalakrishnan et al.,

2007).

In the current study there was always a

negative correlation between nitrogen

concentrations in nutrient solution and NI

activity of root exudates or shoot

homogenates independent of N-forms (data


not presented). However, Subbarao et al.,

(2005-2008) showed that amount of NNI

production and release is a function of

nitrogen status of plant, as well as NH4+

rather than NO3- nutrition, in which higher

nitrogen content of plants leads to more

production of NI compounds. In contrast,

our data support the idea that nitrogen

stress (deficiency) could be the main factor

behind the evolution of NNIs as an

adaptive mechanism, and they are

expressed under N limitation (Ishikawa et

al., 2003; Lata et al., 2004; Subbarao et al.,

2007b). Subbarao et al., (2007c) released a

patent indicating some isomers of

unsaturated linolenic and linoleic fatty

acids show strong NI activity.

Nevertheless, active exudation of fatty

acids specially unsaturated long chain

isomers of linolenic acid is not possible

(Neumann & Römheld, 2000). This could

be possible only through root damage or

passive exclusion of root debris. In

addition, no significant NI activity was

indicated when root exudates were

collected in distilled water, while

significant inhibition effects when

collected in ammonium chloride, indicates

no active release of NNIs. This is further

supported by low pH as an indirect effect

of NH4+ uptake in collecting medium,

which can damage the root cells

membrane, and consequently leaching of

NNIs could occur as a passive

phenomenon (Figure 8).

The inhibitory effect of exudates when

collected in 1mM NH4Cl, might be a

secondary response of BH to salt or

osmotic conditions in collection medium.

Mergulhao et al., (2002) showed that BH is

relatively sensitive to salinity particularly

to chloride in growth medium, with a

succulent effect on leaves and roots which

is more pronounced on roots (Mergulhao et

al., 2002; Cazetta and Villela, 2004). The

same succulent effect was observed in our

pot plants in greenhouse (data not

presented). Therefore, the presence of Cl in

collecting medium may trigger release of

phytoalexins which could have an

inhibitory effect on nitrification, which

further studies are necessary in order to be

clarified. Based on their capabilities, plants

can change their biochemical,

physiological and morphological

characteristics in response to

environmental variations. The nature of

these changes usually determines a species

ability to succeed under temporary or

permanent environmental stress. It is quite

important that interactions among stress

factors that occur parallel in infertile acidic

soils must always be considered (Wenzl et

al., 2003). Nevertheless, the ability of

plants to inhibit nitrification is also

presented in this work (Figure 7), and as

our results showed, under specific

conditions plants can have NI activity in

their root exudates. However, our findings

can not support the idea that BH plants

release controlled root exudates which

strongly and efficiently suppress

nitrification.

Conclusion

There was no detection of NI in root

washings, independent of plant age, light

intensity, collection period, N-form and N

concentrations, except for the ammonium

chloride collecting medium. Therefore,


under proper collection conditions for root

exudates, (avoiding membrane damage and

potential degradation or chemical

modification of exudates compounds due

to extended collection times in distilled

water), there was no evidence for a

controlled release of NI compounds from

Brachiaria roots, independent of plant age,

amount and form of N supply, pH of the

growth medium and light intensity during

the culture period.

However, NI activity was detectable in

root washings when plants were exposed to

extended collection times (24 h) in

combination with NH4+ supply (Figure 7),

but not with NO3- in the collection solution

or after short-term collection (6 h). This

observation is consistent with the findings

of (Subbarao et al., (2005, 2006, 2007 &

2008) but also strongly suggests that the

observed release of NI compounds was

rather a consequence of membrane damage

due to inadequate collection conditions

(Figure 8), rather than mediated by

controlled exudation from undamaged

roots. Supplying only ammonium (1 mM)

in distilled water as root washing medium

over extended time periods (24 h) will lead

to rapid ammonium uptake and medium

acidification associated with the risk of K+

and Ca2+-leaching, as an important element

required for membrane stabilisation.

Accordingly, (Cakmak & Marschner,

1988) reported detrimental effects on

membrane stability in roots of cotton

seedlings due to the lack of Ca2+ in the

washing medium of roots, which was

detectable already after an incubation

period of only six hours.

Figure 7. Nitrification inhibition effect of root exudates collected in distilled water containing 1 mM NH4Cl (6

hours versus 24 hours collection). Plants were grown in nutrient solution with 2mM N-NH4+ or NO3

-. The pH

value for ammonium was ~4 and ~3 for 6 and 24 hours, and pH value for nitrate was ~5 and ~4 respectively.

Data are average of four replicates ± SD. Duncan test was conducted for mean values at P= 0.05.

a

b

a

bc

a ab

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Water control

DMPP control

NH4 6h NH4 24h NO3 6h NO3 24h

Nitr

ite (

mg/

100

g dr

y so

il)


Figure 8. Electric conductivity (µS/m) of root washings collected for the 3 hours period in distilled water, just

after collection of their root exudates for 6 or 24 hours period in 1 mM NH4Cl. Plants were grown with

ammonium, (NH4)2SO4 or with nitrate, Ca(NO3)2. Data are average of four replicates ± SD. Duncan test was

conducted for mean values at P= 0.05.

REFERENCES

Cakmak, I. and Marschner, H. 1988. Increase in

membrane permeability and exudation in roots

of zinc deficient plants. Journal of Plant

Physiology 132: 356-361.

Cazetta, J. O. and Villela, L. C. V. 2004. Nitrate

reductase activity in leaves and stems of tanner

grass (Brachiaria radicans Napper). Brazilia

Scientia Agricola 61: 640-648.

CIAT. 1983. Annual report. International center for

tropical agriculture, Apartado Aereo 6713,

Cali, Colombia, South America.

CIAT. 1985. Annual Report. pp. 222–224.

International center for tropical agriculture,

Apartado Aereo 6713, Cali, Colombia, South

America.

Gopalakrishnan, S., Subbarao, G. V., Nakahara, K.,

Yoshihashi, T., Ito, O., Meada, I., Ono, H. and

Yoshida, M. 2007. Nitrification inhibitors

from the root tissues of Brachiaria. Journal of

Agriculture and Food Chemistry 55: 1385 –

1388.

Ishikawa, T, Watanabe, T. and Minami, K. 1999.

Possibility of nitrification suppression by a

tropical grass. The effect on multiplication of

ammonium-oxidizing bacteria and nitrous

oxide efflux. Japanese Journal of Soil Science

and Plant Nutrition 70: 762-768.

Ishikawa, T., Subbarao, G. V., Ito, O. and Okada,

K. 2003. Suppression of nitrification and

nitrous oxide emission by the tropical grass

Brachiaria humidicola. Plant and Soil 255:

413-419.

Jones, D. L., Hodge, A. and Kuzyakov, Y. 2004.

Plant and mycorrhizal regulation of

rhizodeposition. New Phytologist 163: 459 –

480.

Kandeler, E. 1993. Bodenbiologische

Arbeitsmethoden, Springer- Verlag,

Heidelberg, Germany 163-167.

Lata, C., Degrange, V., Raynaud, X., Maron, P. A.,

Lensi, R. and Abbadie, L. 2004. Grass

populations control nitrification in savanna

soils. Functional Ecology 18: 605-611.

Liljeroth, E. and Baath, E. 1988. Bacteria and fungi

on roots of different barley varieties (Hordeum

vulgare L.). Biology and Fertility of Soils. 7:

53– 57.

B

B

A

A

0

5

10

15

20

25

30

NH4 6h NH4 24h NO3 6h NO3 24h

EC

(µS

/m)


Mergulhao, A., Burity, H. A., Tabosa, J. N.,

Figueiredo, M. and Maia, L. C., 2002.

Influence of NaCl on Brachiaria humidicola

inoculated or not with Glomus etunicatum.

Investigacion Agraria Produccion y

Proteccion Vegetales 17: 219-227.

Nakamura, T., Kanno, T., Miranda, C., Ohwaki, Y.

and Macedo, M. 2005. Characterization of

nitrogen utilization by Brachiara grasses in

Brazilian savannas, (Cerrados). Soil Science

and Plant Nutrition 51: 973-979.

Neumann, G. and Römheld, V. 2000. The release

of root exudates as affected by the plant

physiological status, In: R. Pinton, Z.Varanini,

Z. Nannipieri (eds.) The rhizosphere:

biochemistry and organic substances at the

soil-plant interface. Marcel Dekker 2000.

Römheld, V. and Marschner, H. 1986. Evidence for

a specific uptake system for iron

phytosiderophores in roots of grasses. Plant

Physiology 80: 175–180.

Souri, M.K. 2008. Characterization of natural and

synthetic nitrification inhibitors and their

potential use in tomato culture, PhD

dissertation, University of Hohenheim,

Stuttgart-Germany.

Subbarao, G. V., Ito, O., Wang, H. Y., Nakahara,

K., Suenaga, K. and Rondon, M., Rao, I. M.,

Carlos, L. and Ishitani, M. 2005. Root

exudates of Brachiaria humidicola inhibt

nitrification characterization and quantification

of this unique biological phenomenon. Plant

nutrition for food security, human health and

environmental protection, pp. 444-445.

Subbarao, G. V., Ito, O., Sahrawat, K., Berry, W.

L., Nakahara, K., Ishikawa, T., Watanabe, T.,

Suenaga, K., Rondon, M. and Rao, I. 2006.

Scope and strategies for regulation of

nitrification in agricultural systems-challenges

and opportunities. Critical Reviews in Plant

Sciences 25: 303-335.

Subbarao, G. V., Wang, H. Y., Ito, O., Nakahara,

K. and Berry, W. L. 2007a. NH4+ triggers the

synthesis and release of biological nitrification

inhibition compounds in Brachiaria

humidicola roots. Plant and Soil 290: 245-257.

Subbarao, G. V., Rondon, M., Ito, O., Ishikawa, T.,

Rao, I. M., Nakahara, K., Carlos, L. and Berry,

W. L. 2007b. Biological nitrification inhibition

(BNI)-is it a widespread phenomenon?. Plant

and Soil 294: 5-18.

Subbarao, G. V., Nakahara, K., Ishikawa, T., Ito,

O., Ono, H., Kameyama, M., Yoshida, M.,

Rondon, M., Rao, I. M., Lascano, C. and

Ishitani, M. 2007c. Nitrification inhibitor and

soil improver and fertilizer containing the

same, United States Patent 20070028659.

http://www.freepatentsonline.com/200700286

59.html. (accessed 5 July 2007).

Subbarao, G. V., Nakahara, K., Ishikawa, T.,

Yoshihashi, T., Ito, O., Ono, H., Ohnishi-

Kameyama, M., Yoshida, M., Kawano, N. and

Berry, W. L. 2008. Free fatty acids from the

pasture grass Brachiaria humidicola and one

of their methyl esters as inhibitors of

nitrification. Plant and Soil 313: 89-99.

Sylvester-Bradley, R., Mosquera, D. and Mendez,

J. E. 1988. Inhibition of nitrate accumulation

in tropical grassland soils: effect of nitrogen

fertilization and soil disturbance. Journal of

Soil Science 39 : 407–416.

Wang, H. Y., Subbarao, G. V., Ito, O. and

Nakahara, K. 2005. Regulation of nitrification

inhibitory (NI) activity in the root exudates of

Brachiaria humidicola. Plant Nutrition for

Food Security, Human Health and

Environmental Protection, pp. 478-479, China.

Wenzl, P., Mancilla, L. I., Mayer, J. E., Albert, R.

and Idupulapati, M. R. 2003. Simulation

infertile acid soils with nutrient solutions: The

effects on Brachiaria species. Soil Science

Society of American Journal 67: 1457-1469.


چكيده

هاي وحشي اين اثرات ممانعت كنندگي يك ويژگي ژنوتيپ. باشدهاي طبيعي چندين دهه است كه مطرح ميممانعت از نيتريفيكاسيون در اكوسيستم

ها نشان داده شده اند كه داراي اين خاصيت ممانعت از نيتريفيكاسيون هستند و اخيراً برخي بسياري از گياهان مخصوصاً گراس. باشد تا ارقام تجاريمي

ها در كاهش ميزان نيتريفيكاسيون در خاك از طريق را به سبب نقش آنتوجه زيادي humidicola Brachiaria مخصوصاً Brachiariaهاي ژنوتيپ

در اين مطالعه طي يك سري آزمايشات كشت هيدروپونيك نشان داده شد كه وقتي ترشحات ريشه اي اين گياه در . ترشحات ريشه اي جلب نموده است

و طول مدت جمع آوري ترشحات ريشه، ترشحات ريشه اين گياه هيچ اثر آب مقطر جمع آوري گرديد، جدا از فرم و غلظت نيتروژن، شدت نور، سن گياه

به ، آنميلي مول كلريد آمونيم جمع آوري گرديد يكبه هر حال وقتي ترشحات ريشه در محيطي حاوي . معني داري بر فرايند نيتريفيكاسيون نداشت

نمونه .با نيترات بود رشد يافتهبا آمونيم بيشتر از گياهان رشد يافتهي در گياهان و اين اثر ممانعت كنندگ نمودطور معني داري از نيتريفيكاسيون ممانعت

رايط هاي جمع آوري شده ترشحات ريشه وفتي ليوفياليز شدند، عصاره استخراج شده ترشحات ريشه اي گياهان روئيده با آمونيم و آن هم تنها تحت ش

از جمع بعد(ترشحات ريشه در آب مقطر هدايت الكتريكي اندازه گيري .نيتريفكاسيون را باعث گرديد، ممانعت از )و نه نور متوسط يا زياد(شدت نور كم

هدايت الكتريكي بيشتر تحت شرايطي بود كه آمونيم در محيط ريشه، بيان كننده ) آوري ترشحات ريشه در محلول يك ميلي مول كلريد آمونيم

. وجود داشت) ساعت 6ساعت بجاي 24(راي مدت طوالني مخصوصاً طي مرحله جمع آوري ترشحات ريشه اي، ب

، هدايت الكتريكي، ترشحات ريشه، آمونيم، نيتراتBrachiaria humidicola :كليدي كلمات


Mouse Barley Germination Environmental Factors Influencing Germination of Mouse Barley (

1Assistant Professor, University of Birjand

(Received 13 July 2009; returned 25 Jun 2010; accepted 6 December 2010)

ABSTRACT

Mouse barley (Hordeum murinum

weed in wheat fields of South

grass weed will contribute to development of its control programs. Effects of environmental

factors on germination and emergence of mouse barley was investigated in the laboratory.

Although mouse barley germination was greater than 85% at salinity level of 160 mM, further

increase of salinity caused a remarkable decrease in its germination

in germination at salinity level of 320mM. Increasing osmotic potential from 0 to

resulted in an 80% decrease in its germination. Mouse barley germination was not affected by

the pH and in a pH range of 4 to 10 remained approximately 90%. Emergence depth test

showed that the maximum emergence of mouse barley occurred for seeds

surface (86%) and no seedlings emerged from the seeds buried at 10cm depth. High

germination ability of mouse barley under diverse environmental conditions may greatly

contribute to it as a problematic weed species in the wheat fields of

Keywords: Salinity, osmotic potential, emergence depth, acidity.



Barley Germination Environmental Factors Influencing Germination of Mouse Barley (Hordeum murinum L.) in South Khorasan

Province, Iran

S. V. Eslami1*, F. Afghani2

Assistant Professor, University of Birjand 2 MS Student of Weed Science, University of Birjand.

(Received 13 July 2009; returned 25 Jun 2010; accepted 6 December 2010)

Hordeum murinum), from the poaceae family, is an abundant annual grass

weed in wheat fields of South Khorasan province. Determining the ecological factors of this



e barley germination was greater than 85% at salinity level of 160 mM, further

increase of salinity caused a remarkable decrease in its germination, following a 3% decrease

in germination at salinity level of 320mM. Increasing osmotic potential from 0 to



showed that the maximum emergence of mouse barley occurred for seeds



contribute to it as a problematic weed species in the wheat fields of the region.

Salinity, osmotic potential, emergence depth, acidity.

[email protected]

Barley Germination Environmental Factors Influencing L.) in South Khorasan

MS Student of Weed Science, University of Birjand.

), from the poaceae family, is an abundant annual grass

Khorasan province. Determining the ecological factors of this



e barley germination was greater than 85% at salinity level of 160 mM, further

, following a 3% decrease

in germination at salinity level of 320mM. Increasing osmotic potential from 0 to -0.8 MPa,



showed that the maximum emergence of mouse barley occurred for seeds placed on the soil



the region.

28 Eslami and Afghani (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Mouse barley, also referred to as barley

grass or wild barley, is a winter annual

grass that grows in non cropland and

croplands of Southern Khorasan. Its native

range extends from central Europe, south

to northern Africa and east to western Asia

and the Caucasus (USDA, ARS 2005).

Mouse barley grows well in warm and dry

areas, while cold and moist conditions

hinder its growth (Davison, 1977). It

propagates by seeds which are produced in

large number (Halloran & Pennell 1981). It

is a successful invader species, in disturbed

and, soil high in nutrient levels and

nitrogen (Dean, 1990). Mouse barley

establishes easily on land subjected to

regular grazing and becomes dominant

with increasing intensity of grazing

(Groves et al., 2003). After flowering in

the spring, the grass matures rapidly to

produce a large number of seeds. The

majority of mouse barley seeds remain

dormant during the summer till autumn.

Seed dormancy is an important mean of

avoiding the catastrophes that weeds

encounter (Baker, 1974) and the ability of

a seed to persist in the soil is favorable in

disturbed habitats where synchronous

germination could result in the mortality of

all plants (Cohen, 1966; Westoby, 1981).

The high level of dormancy is usually a

general characteristic of annual weeds that

results in large, persistent seed banks

(Anderson, 1990). An appropriate seed

dormancy strategy will enable winter weed

species to germinate under favorable

conditions of late autumn and winter and

also prevents germination after summer

rains, which are invariably followed by a

period of drought (Dunbabin & Cocks,

1999).

The success of mouse barley as an invader

specie throughout the world has been

attributed to its early germination and rapid

growth rate, seed dormancy, high seed

production and efficient dispersal

mechanisms. It has a short life cycle and

19 to 29 seeds are produced per head

(Dean, 1990).

Various environmental factors, such as

temperature, osmotic potential, pH, light

quality, management practices and seed

location in the soil seed bank as well as

soil texture have been known to influence

weed seed germination and emergence

(Norsworthy & Oliveira, 2006). To

understand why mouse barley is so

troublesome, it is important to gain a better

understanding of how its seeds germinate

in response to different environmental

factors such as light, temperature, osmotic

potential, pH, and burial depth (Chachalis

& Reddy, 2000; Chauhan & Johnson,

2008). A better understanding of mouse

barley germination could aid strategies to

manage this weed. Develop offing models

helps to predict germination and

emergence or the influence of tillage and

burial on the two mentioned processes.

Longevity is influenced by several factors,

including the physiological status of seeds,

the chemical and physical environment

where seeds reside, and the position of

seeds relative to the soil surface (Baskin &

Baskin, 1998).

Although mouse barley is a problematic

weed species in Southern Khorasan cereal

Mouse Barley Germination Environmental Factors … 29

farms (Tareghian, 2002), little information

on effects of environmental factors on its

germination biology exists. Knowledge

about mouse barley germination would

help estimating the potential of its spread

to new croplands. Therefore, this study

was conducted in order to understand the

influence of different environmental

factors on the seed germination and

seedling emergence of mouse barley.


Site and Seed Description

Mature mouse barley seeds were collected

in June 2007, from several wheat fields at

the Amirabaad Campus, Birjand, in

Southern Khorasan (latitude = 32º 56´N,

longitude = 59º 13´E and 1480 m altitude).

Seeds from 500 plants were separated from

the inflorescence and pooled to obtain seed

samples. 3 months after maturity, the seeds

were stored in paper bags at a constant

temperature (4 ± 1C). An 1,000-seed

weight of mouse barley was 4.2 ± 0.01 g.

General Protocol for Germination Tests

Four 25-seeds of mouse barley were placed

in 9-cm petri dishes lined with 2 discs of

filter paper, moistened with either 5mL

deionized water or treatment solution when

required. The petri dishes were sealed with

parafilm to minimize evaporation and

placed directly in the germinator or

wrapped in two layers of aluminum foil to

exclude light prior to placing them in the

germinator. Germination tests were

conducted for 14 days at a day/night

temperature of 25 ◦C/15◦C (12h/12h).

Seeds were considered to have germinated

when the radicle emerged. The number of

germinated seeds was counted at the end of

the germination test. In preliminary testing,

freshly harvested seeds placed in petri

dishes did not germinate under normal

laboratory conditions.

Temperature and Light

Experiments were conducted to determine

the effects of various fluctuating day/night

temperatures (15/6, 20/10, 25/15, 30/15 &

35/20 ◦C) on seed germination (3 months

after maturity) under light/dark and

continuous dark regimes. This temperature

regime was chosen to simulate the late

summer and autumn temperatures in

Southern Khorasan.

Salinity

Sodium chloride solutions of 0, 10, 20, 40,

80, 160, 320 and 640 mM were prepared in

deionized water. These salinity

concentrations were chosen to cover

variations in the level of salinity in South

Khorasan soils. Petri dishes were incubated

as described in the general protocol under

light/dark regime.

Solution Osmotic Potential

Mouse barley seeds were germinated in the

light/dark in aqueous solutions of

polyethylene glycol 6000 with osmotic

potentials of 0, -0.1, -0.2, -0.4, -0.6, -0.8,

and -1.0 MPa, prepared by dissolving

appropriate amounts of PEG 60002 in

deionized water (Michel, 1983).

PH

The effect of pH on germination was

studied using buffer solutions of pH = 4 to

10 according to the method described by

Chachalis & Reddy (2000). A 2 mM

potassium hydrogen phthalate buffer

solution was adjusted to pH 4 with 1 N

HCl. A 2 mM solution of MES [2-(N-

morpholino) ethanesulfonic acid] was


adjusted to pH 5 and pH of 6 with a 1 N

NaOH. A 2-mM solution of HEPES [N-(2-

hydroxymethyl) piperazine- N-(2-

ethanesulfonic acid)] was adjusted to pH 7

and pH 8 with 1 N NaOH. Buffer solutions

of pH 9 and pH 10 were prepared with 2-

mM tricine [N-Tris(hydroxymethyl

methylglycine] and adjusted with 1 N

NaOH. Petri dishes were incubated at

25/15 ◦C day/night temperature as

described in the general protocol.

Emergence Depth

The effect of different planting depths on

seedling emergence of mouse barley was

investigated in a growth chamber. Seeds

were placed at five different depths (0 cm

or surface, 2.5, 5, 7.5, and 10 cm) in 15-

cm-diam plastic pots. Control pots, where

seeds were not added, indicated that there

was no background seed bank of mouse

barley in the study soil. Moist soil was

placed over sown seeds to the appropriate

depth and gently compacted. For each

burial depth, four pots (replicates), with 50

seeds per pot were set up (total of 20 pots).

Soil used for this experiment was a loamy

soil comprised of 43% sand, 32% silt and

25% clay with 0.44% total organic matter

and a pH of 7.4. The temperature of the

growth cabinet was set to 25/15 ◦C

(day/night). The photoperiod was set to 12

hours with fluorescent lamps used to

produce a light intensity of 140 µmol m-2

s-1. The pots were watered as needed to

maintain adequate soil moisture. Seedlings

were counted as they emerged through the

soil and the experiment was run till 45

days after burial. Mean emergence time

(MET) was calculated using the following

formula

in which, n is the number of seedlings

emerging per day, g is the number of days

needed for emergence, and N is the total

number of emerged seeds. At the end of

the experiment, seeds buried at 10 cm

depth were recovered to determine the fate

of non germinated seeds. The soil was

filtered using a 1 mm mesh metal sieve to

recover intact (dormant) seeds as well as

seedlings that were rotting due to failure of

emergence after germination. This

procedure made it possible to distinguish

between seeds that remained dormant and

germinated seeds that failed to emerge due

to excessive depth of burial.

Data Analysis

All experiments were carried out twice

(except the emergence depth study) as a

completely randomized design with four

replicates per treatment. The data of the

experiments were pooled for analysis, as

there was no time-by-treatment interaction.

A functional three parameter logistic

model (Chauhan et al., 2006a) as

expressed below:

G (%) = Gmax/[1 + (x/x50)Grate] [1]

was fitted to the germination values (%)

obtained at different concentrations of

NaCl or osmotic potential using

SigmaPlot3 (version 11.0). In this equation,

G represents the total germination (%) at

NaCl concentration or osmotic potential x,

Gmax is the maximum germination (%), x50

is the NaCl concentration or osmotic

potential for 50% inhibition of the

maximum germination, and Grate indicates

the slope. The seedling emergence values

MET n g N= ×∑ ( ) /


(%) obtained at different burial depths

were fitted to a sigmoidal decay curve

(Norsworthy and Oliveira, 2006) in the

form of:

E (%) = Emax/ (1+ exp(-(x-x50)/ Erate)) [2]

where E represents the seedling emergence

(%) at burial depth x, Emax is the maximum

seedling emergence, x50 represents the

depth at which emergence is reduced by

50%, and Erate indicates the slope.

Transformation of data did not improve

homogeneity; therefore, ANOVA and

regression analysis were performed on

non-transformed percentage of germination

(Genstat4, version 9.2). Means were

separated using either LSD test at P = 0.05

or standard error bars.


Temperature and Light

Although light and fluctuating

temperatures can be important in

stimulating germination of many

agricultural weeds, the impact of

temperature and light on mouse barley

germination was insignificant (data not

shown). There was no interaction between

temperature and light. Mouse barley

showed high germination (>90%) at all

tested temperatures under both light/dark

and continuous dark regimes. Results

showed that mouse barley could germinate

over a wide range of temperature regimes

from 15/6 to 35/20 ◦C alternating day/night

temperatures. Studies in Australia similarly

showed that germination of mouse barley

occurred at constant temperatures ranging

from 7 to 32 ◦C, with optimum

temperatures between 18 and 24 ◦C

(Groves et al., 2003). The effect of large

diurnal temperature swings on the

germination was insignificant (Cocks &

Donald, 1973, Piggin et al., 1973, Popay,

1981). The ability of mouse barley to

germinate over a wide range of

temperatures supports the extended period

of its emergence in the field throughout

most autumn and winter months in south

Khorasan.

This study also indicated that mouse barley

does not require light for germination

(non-photoblastic). Exposure to light

breaks dormancy in many weed species,

but there are species in which light has no

effect or may even inhibit germination.

Grime and Jarvis (1976) also found that

mouse barley seeds maintained under high

or low light intensity or in darkness,

germinated completely in all conditions.

Baskin and Baskin (1998) summarized that

among 54 grass species, germination of 28

was promoted by light, 13 were unaffected

by light or dark conditions, and 13 were

inhibited by light. Milberg et al., (1996)

tested 44 species, mostly agricultural

weeds, and found that germination

improved in 24 species after a 5-s exposure

to light. In the remaining 20 species, there

were no effects. Buhler, (1997) found that

germination percentage of annual grasses

like Echinochloa crus-galli L., Alopecurus

myosuroides Huds, and Setaria glauca L.

were similar under presence or absence of

light. Seed germination of Atriplex stocksii

Boiss. (Khan & Rizvi, 1994) and Suaeda

fruticosa Forssk.(Khan & Ungar, 1998)

were not inhibited by the absence of light.

Germination of Aegilops cylindrica host

has also been shown to be insensitive to


light and dark conditions (Baskin &

Baskin, 1998). In situations where light

promotes germination, it has been

associated with small, rather than large

seed masses (Milberg et al., 2000; Schutz

et al., 2002).

Salinity

The three-parameter logistic model {G (%)

= 98.6/[1 + (x/207.9)8.6], r2 = 0.99}

provided a satisfactory fit for the data of

mouse barley seed germination obtained at

different concentrations of NaCl (Figure

1). Germination was greater than 95% up

to 80 mM NaCl and also high at 160 mM

NaCl (> 85%). Increasing NaCl

concentration to 320 mM sharply

decreased mouse barley germination

(<3%). The parameter x50 (Equation 1) that

represents the NaCl concentration for 50%

inhibition of the maximum germination,

was 207.9 mM NaCl, indicating a

moderately salt tolerance in this species at

germination stage. The results show that

mouse barley would be able to germinate

even at saline soil types which are common

in Southern Khorasan (Forooghifar &

Shahidi, 1999).

Figure 1. Effect of NaCl concentration on germination of mouse barley seed incubated at 25/15 ◦C day/night

temperature with a 12-hour photoperiod for 2 weeks.

Solution Osmotic Potential

Increased solution osmotic potentials

reduced mouse barley germination (Figure

2). Increasing osmotic potential from 0 to –

0.6 MPa caused an 80% reduction in

mouse barley germination.

G (%) = 98/6/[1 + (x / 207/9)8.6], r2 = 0.99

NaCl concentration (mM)

0 100 200 300 400 500 600

Ger

min

atio

n (

%)

0

20

40

60

80

100


Figure 2. Effect of osmotic potential on germination of mouse barley seed incubated at 25/15 ◦C day/night

temperature with a 12-hour photoperiod for 2 weeks.

The three-parameter logistic model {G (%)

= 98.9/[1 + (x/0.40)4.2], r2 = 0.99}

provided a satisfactory fit for the data of

mouse barley seed germination obtained at

different osmotic potentials. As osmotic

potential decreased from 0 to -0.6 MPa,

mouse barley seed germination decreased

from 98 to 20%. No germination occurred

when the osmotic potential was -0.8 and -

1.0 MPa.

The osmotic potential required for 50%

inhibition of maximum germination (x50),

determined from the fitted model

(Equation 1) was -0.40 MPa. Although at

lower incidence, mouse barley can still

germinate under moderate water-stress

conditions. Germination over a broad

range of osmotic potentials indicates that

mouse barley could pose a weed threat

under both adequate and moderate

moisture-stress soil conditions.

PH

Mouse barley seeds germinated greater

than 90% over a pH range from 4 to 10

(data not shown) while most soils of South

Khorasan fall in the neutral to alkaline

range (Forooghifar & Shahidi, 1999).

These results suggest that pH should not be

a limiting factor for germination of this

weed species in most soils. Similar to

mouse barley, other weed species,

including annual sowthistle (Sonchus

oleraceus L. SONOL) (Chauhan et al.,

2006a) horseweed (Conyza canadensis L.

Cronq. ERICA) (Nandula et al., 2006)

texasweed [Caperonia palustris (L.) St.

Hil.] (Koger et al., 2004), and giant

sensitiveplant (Mimosa invisa Mart. ex

Colla MIMIN) (Chauhan & Johnson,

2008), germinated in a wide range of pH.

High germination of mouse barley over a

broad range of pH has implications for a

widespread distribution and infestation in

South Khorasan.

Emergence Depth

Depth of burial strongly influences

seedling emergence. Germination was

noted the 9th day after establishing the

experiment for seeds placed on the soil

surface (27%) and for seeds sown at 2.5

cm (21%) (data not shown). Mouse barley

emergence was influenced by seeding

depth (P < 0.001). Increasing the seeding

G (%) = 98/9 / [1 + (x / 0.40)4.21], r 2= 0.99

Osmotic potential (-MPa)

0.0 0.2 0.4 0.6 0.8 1.0

Ger

min

atio

n (

%)

0

20

40

60

80

100


depth decreased emergence percentage and

also delayed the emergence time (Figure

3). The greatest mouse barley emergence

occurred for seeds placed on the soil

surface (86%) and no seedlings emerged

from burial depth 10 cm. The sigmoidal

decline model {E (%) = 84.2 / (1 + exp (-

(x-4.7)/-1.2)), r2 = 0.97} was best fitted to

the data of mouse barley emergence in

relation to seeding depth (Figure 4).

According to the model, the seeding depth

that decreased mouse barley emergence by

50% was 4.5 cm. Popay and Sanders

(1975) also reported that mouse barley

seedlings from seed sown on the soil

surface emerged well but the seed was

slow in germination. They also found that

seed sown at 2 mm below the surface or at

2.5 cm deep emerged well but with seed

sown at 5, 7.5, and 10 cm emergence was

gradually declined.

Figure 3. Effect of seeding depth on seedling emergence (as percentage of soil surface germination) and mean

emergence time (MET) of mouse barley seedlings. Vertical bars represent standard errors.

Emergence of weeds is affected by the

amount of food reserves in seeds and the

depth of seed burial in the soil. Decreased

emergence due to increased planting depth

has been reported in several weed species,

including horseweed (Conyza canadensis

L.) (Nandula et al., 2006), sicklepod

(Senna obtusifolia L.) (Norsworthy &

Oliveira, 2006), and African mustard

(Brassica tournefortii L.) (Chauhan et al.,

2006b). Roberts, (1986) found that mouse

barley seeds sown in a 7.5 cm layer of soil

in cylinders sunk in the field, emerged

mainly in the year of sowing with less than

1% of seedlings emerging in year 2 and

none thereafter. Recovery of

nongerminated seeds showed that failure to

emerge was almost entirely the result of

fatal germination (95%), rather than re-

induction of dormancy. Similarly (Popay

& Sanders, 1975) found that the mouse

barley seeds sown deeper than 10 cm did

germinate but failed to emerge. Therefore,

it is thought to be unlikely that mouse

barley would build up a large seedbank in

the soil. As mouse barley does not form

long seed bank duration (Popay & Sanders,

1975), burial of seed by deep summer

Seeding depth (cm)

0.0 2.5 5.0 7.5 10.0

ME

T (

d)

0

5

10

15

20

25

30

Em

erg

ence

(%

of

surf

ace

ger

min

atio

n)

0

20

40

60

80

100

METEmergence


tillage may prevent germination in the

following autumn. Emergence from depth

of 7.5 cm could allow mouse barley to

escape control with pre-emergence

herbicides.

Figure 4. Effect of seed burial depth on seedling emergence (%) of mouse barley in a growth chamber

maintained at 25/15 ◦C (day/night) temperature.

Our data suggest that mouse barley is able

to germinate under a broad range of

environmental conditions. Light,

temperature and solution pH levels used in

this study had little impact on mouse

barley germination. On the contrary, water

stress, salinity and depth of burial affected

seed germination of this weed. Deep tillage

may prevent emergence of this

troublesome weed species and can be

adopted as an effective tool for its control

as it showed fatal germination at deep

burial depths.

REFERENCES

Anderson, S. 1990. The relationship between seed

dormancy, seed size and weediness, in Crepis

tectorum (Asteraceae). Oecologia 83: 277-280.

Baker, H. G. 1974. The evolution of weeds. Annual

Review of Ecology Systematics 5:1-24.

Baskin, C. C. and Baskin, J. M. 1998. Seeds:

ecology, biogeography, and evolution of

dormancy and germination. San Diego:

Academic Press. Pp. 27–47.

Buhler, D. D. 1997. Effects of tillage light

environment on emergence of 13 annual

weeds. Weed Technology 11:496-501.

Chachalis, D. and Reddy, K. N. 2000. Factors

affecting Campsis radicans seed germination

and seedling emergence. Weed Science

48:212–216.

Chauhan, B. S., Gill, G. & Preston, C. 2006a.

Factors affecting seed germination of annual

sowthistle (Sonchus oleraceus) in southern

Australia. Weed Science 54:658–668.

Chauhan, B. S., Gill, G. and Preston, C. 2006b.

African mustard (Brassica tournefortii)

germination in southern Australia. Weed

Science 54:891–897.

Chauhan, B. S. and Johnson, D. E. 2008. Seed

germination and seedling emergence of giant

sensitiveplant (Mimosa invisa). Weed Science

56:244–248.

Cocks, P. S. and Donald, C. M. 1973. The

germination and establishment of two annual

pasture grasses (Hordeum leporinum Link. and

Lolium rigidum Gaud.). Australian Journal of

Agricultural Research 24: 1-10.

E(%) = 90.0 / (1 + exp (- (x- 4.5) / -1.6)), r2 = 0.97

Burial depth (cm)

0 2 4 6 8 10

Em

erg

ence

(%

)

0

20

40

60

80

100


Cohen, D. 1966. Optimizing reproduction in a

randomly varying environment. Journal of

Theoretical Biology 12:119-129.

Davison, A. W. 1977. The ecology of Hordeum

murinum L. III. Some effects of adverse

climate. Journal of Ecology 65: 523-530.

Dean, S. A. 1990. Hordeum murinum spp.

leporinum—wild barley. Element Stewardship

Abstract. The Nature Conservancy. Available

online at:

http://tncweeds.ucdavis.edu/esadocs/documnts

/hordmu1.html; accessed May 2004.

Dunbabin, M. T. and Cocks, P. S. 1999. Ecotypic

variation for seed dormancy contributes to the

success of capeweed (Arctotheca calendula) in

Western Australia. Australian Journal of

Agricultural Research 50: 1451-1458.

Forooghifar, H. and Shahidi, A. 1998. A case study

of morphological, physical and chemical

characteristics of farmland soils of South

Khorasan province. Birjand University, Iran,

Pp 32-67.(In Persian with English Summary).

Grime, J. P. and Jarvis, B. C. 1976. Shade

avoidance and shade tolerance in flowering

plants II. Effects of light on the germination of

species of contrasted ecology. Reprinted from:

Light as an Ecological Factor :II, The 16th

Symposium of the British Ecological Society,

1974, Blackwell Scientific Publications,

Oxford, Pp 525-532.

Groves, R. H., Austin, M. P. and Kaye, P. E. 2003.

Competition between Australian native and

introduced grasses along a nutrient gradient.

Australian Journal of Ecology 28: 491-498.

Halloran, G. M. and Pennell, A. L. 1981.

Regenerative potential of barley grass

(Hordeum leporinum). Journal of Applied

Ecology 18: 805-813.

Khan, M.A. and Rizvi, Y. 1994. Effect of salinity,

temperature, and growth regulators on the

germination and early seedling growth of

Atriplex griffithii var. stocksii. Canadian

Journal of Botany 72: 475–479.

Khan, M. A. and Ungar, I. A. 1997. Effect of

thermoperiod on recovery of seed germination

of halophytes from saline conditions.

American Journal of Botany 84: 279–283.

Koger, C. H., Reddy, K. N. and Poston, D. H. 2004.

Factors affecting seed germination, seedling

emergence, and survival of texasweed

(Caperonia palustris). Weed Science 52:989–

995.

Michel, B. E. 1983. Evaluation of the water

potentials of solutions of polyethylene glycol

8000 both in the absence and presence of other

solutes. Pl. Physiol 72:66–70.

Milberg, P., Andersson, L. and Noronha, A. 1996.

Seed germination after short-duration light

exposure: implications for the photo-control of

weeds. Journal of Applied Ecology 33:1469–

1478.

Milberg, P., Andersson, L. and Thompson, K. 2000.

Large-seeded species are less dependent on

light for germination than small-seeded ones.

Seed Science Research 10:99–104.

Nandula, V. K., Eubank, T. W., Poston, D. H.,

Koger, C. H. and Reddy, K. N. 2006. Factors

affecting germination of horseweed (Conyza

canadensis). Weed Science 54:898-902.

Norsworthy, J. K. and Oliveira, M. J. 2006.

Sicklepod (Senna obtusifolia) germination and

emergence as affected by environmental

factors and seeding depth. Weed Science 54:

903-909.

Piggin, C. M., Hallett, M. L. and Smith, D. F. 1973.

The germination response of seed of some

annual pasture plants to alternating

temperatures. Seed Science Technology 1:

739-748.

Popay, A. I. and Sanders, P. 1975. Effect of depth

of burial on seed germination and seedling

emergence of barley grass (Hordeum murinum

L.). New Zealand Journal of Experimental

Agriculture 3: 77-80.

Popay, A. I. 1981. Germination of seeds of five

annual species of barley grass. Journal of

Applied Ecology 18: 547-558.


Roberts, H .A. 1986. Persistence of seeds of some

grass species in cultivated soil. Grass and

Forage Science 41: 273-276.

Schutz, W., Milberg, P. and Lamont, B. B. 2002.

Seed dormancy, after-ripening and light

requirements of four annual Asteraceae in

South-western Australia. Annals of Botany 90:

707-714.

Tareghian, M. R. 2002. Identification of weeds of

cereal farms in South Khorasan. Research

project, Faculty of Agriculture, Birjand

University.( In Persian with English

Summary).

USDA, ARS. 2005. National Genetic Resources

Program. Germplasm Resources Information

Network - (GRIN) [Online Database]. National

Germplasm Resources Laboratory, Beltsville,

Maryland. URL:

http://www.arsgrin.gov/var/apache/cgibin/npgs

/html/taxon.pl?300618 (April 14, 2005).

Westoby, M. 1981. How diversified seed

germination behavior is selected. The

American Naturalist 118 : 882-885.


چكيده

مشكل جوموشي، علف هرزي يكساله از خانوادة گندميان، در مزارع گندم استان خراسان جنوبي به وفور يافت شده و كنترل آن در برخي مزارع بسيار

شدن ززني و سباثرات عوامل محيطي مختلف بر جوانه. هاي كنترل آن كمك خواهد كردهرز به توسعة برنامهزني اين علفشناخت اكولوژي جوانه. است

درصد بود، افزايش 85زني بيش از موالر كلرور سديم، ميزان جوانهميلي 160چه در شوري معادل اگر. جوموشي در آزمايشگاه مورد تحقيق قرار گرفت

درصد 3زني به موالر، ميزان جوانهميلي 320زني گرديد، به طوري كه در شوري اي در جوانهسطح شوري از آن به بعد منجر به كاهش قابل مالحظه

زني جوموشي به وسيلة جوانه. درصد گرديد 80زني به ميزان مگاپاسكال، منجر به كاهش جوانه -8/0افزايش پتانسيل اسمزي از صفر به . كاهش يافت

pH تحت تأثير قرار نگرفت و در دامنةpH كثر سبز شدن اين علفآزمايش عمق سبز شدن نشان داد كه حدا. درصد باقي ماند 90در حدود 10تا 4از -

زني باالي قابليت جوانه. سانتيمتري خاك سبز نشد 10اي از بذور دفن شده در عمق و هيچ گياهچه) درصد 86(هرز از بذور سطح خاك حاصل شد

دم منطقه سهيم ساز در مزارع گنجوموشي تحت شرايط محيطي متفاوت ممكن است تا حد زيادي در موفقيت اين علف هرز به عنوان يك گونة مشكل

.باشد

شوري، پتانسيل اسمزي، عمق رويش، اسيديتي: كليديكلمات


Corn and Soybean Intercropping Canopy Structure as Affected by Competition from Redroot Pigweed (

Jimson Weed (

M. Aghaalikhani1*, F. Zaefarian1Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran,

Agronomy and Plant Breeding, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran. 3Department of Weed Research, Iranian Plant Protection Research Institute, Iran.

Faculty of Agriculture, University of

Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran(Received 17 January 2010; returned 16 June 2010; accepted 25 May 2011)

ABSTRACT

In order to determine the role of plant leaf area

a better understanding of how crops and weeds intercept light a study of the complexity of

plants is necessary. The effect of intercropping on leaf area distribution and dry matter

accumulation in corn, soybean and weeds canopy was studied in a field experiment at a

research field of Tehran University (Karaj campus), during 2007 growing season. Treatments

were arranged in a factorial experiment based on randomized complete blocks with three

replications. The treatments were five different mixing ratios of corn (

soybean (Glycine max L.) including 100/0, 75/25, 50/50, 25/75 and 0/100 (corn/soybean).

Crops were planted at four levels of weed infestations, including weed free, infested to

redroot pigweed (Amaranthus retroflexus

stramonium L., DASTR) and mixed stands of both weeds species

Results showed that in weed free

distributed in 90-120 cm layer, but when corn was grown with

both weed species (DASTR+AMRET), the maximum

layer. Soybean weed free monoculture produced 34.66% of its total biomass in the layer of

30-60 cm, but contaminated soybean with

in the 60-90 cm layer. In this treatment

the 120-150 cm layer. Soybean canopy in monoculture couldn’t compete with weeds and was

suppressed, but intercropped soybean with the corn especially in 50%: 50% mixing ratio,

suppressed the weeds successfully. Therefore we can concluded that complementarily effect

of corn/soybean intercropping created better condition for optimum utilization of s

radiation to successfully suppress weeds and maintain crop production.

Key words: canopy structure, leaf area distribution, legume/cereal intercropping


Corn and Soybean Intercropping Canopy Structure as Affected by Competition from Redroot Pigweed (Amaranthus retrofelxus

Jimson Weed (Datura srtramonium L.)

, F. Zaefarian2 , E. Zand3 , H. Rahimian Mashhadi4 and M. Rezvani

Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran,

Agronomy and Plant Breeding, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran.

Department of Weed Research, Iranian Plant Protection Research Institute, Iran.4Department of Agronomy,

Faculty of Agriculture, University of Tehran, Tehran, Iran.5 Department of Agronomy and Plant Breeding,

Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran (Received 17 January 2010; returned 16 June 2010; accepted 25 May 2011)

In order to determine the role of plant leaf area in radiation distribution within the canopy and



ean and weeds canopy was studied in a field experiment at a



treatments were five different mixing ratios of corn (

L.) including 100/0, 75/25, 50/50, 25/75 and 0/100 (corn/soybean).


Amaranthus retroflexus L., AMRET), infested to jimsonweed

L., DASTR) and mixed stands of both weeds species (DASTR+AMRET)

weed free corn pure stand, 30.36% of the maximum leaf area

120 cm layer, but when corn was grown with jimsonweed

both weed species (DASTR+AMRET), the maximum leaf area were established in the upper

Soybean weed free monoculture produced 34.66% of its total biomass in the layer of

but contaminated soybean with DASTR+AMRET, allocated 32.97% of its biomass

90 cm layer. In this treatment DASTR had also its maximum biomass (49.54%) in

150 cm layer. Soybean canopy in monoculture couldn’t compete with weeds and was

essed, but intercropped soybean with the corn especially in 50%: 50% mixing ratio,


of corn/soybean intercropping created better condition for optimum utilization of s

radiation to successfully suppress weeds and maintain crop production.

canopy structure, leaf area distribution, legume/cereal intercropping

Corn and Soybean Intercropping Canopy Structure as Affected by Amaranthus retrofelxus L.) and

and M. Rezvani5

Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran, 2Department of

Agronomy and Plant Breeding, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran.

Department of Agronomy,

Department of Agronomy and Plant Breeding,

in radiation distribution within the canopy and



ean and weeds canopy was studied in a field experiment at a



treatments were five different mixing ratios of corn (Zea mays L.) and

L.) including 100/0, 75/25, 50/50, 25/75 and 0/100 (corn/soybean).


L., AMRET), infested to jimsonweed (Datura

(DASTR+AMRET).

the maximum leaf area was

jimsonweed or infested with

were established in the upper

Soybean weed free monoculture produced 34.66% of its total biomass in the layer of

, allocated 32.97% of its biomass

had also its maximum biomass (49.54%) in

150 cm layer. Soybean canopy in monoculture couldn’t compete with weeds and was

essed, but intercropped soybean with the corn especially in 50%: 50% mixing ratio,


of corn/soybean intercropping created better condition for optimum utilization of solar

canopy structure, leaf area distribution, legume/cereal intercropping

40 Aghaalikhani et al. (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Amount and vertical distribution of leaf

area are essential for estimating

interception and utilization of solar

radiation of crop canopies and,

consequently dry matter accumulation

(Sivakumar & Virmani, 1984; Valentinuz

& Tollenaar, 2006). Vertical distribution of

leaf area is leaf areas per horizontal layers,

based on height (Boedhram et al., 2001).

The presence of weeds intensifies

competition for light, with the effect being

determined by plant height, position of the

branches, and location of the maximum

leaf area (Holt, 1995).

The effect of leaf area distribution on light

competition can be illustrated by dividing

the canopy into horizontal layers (Wiles &

Willkerson, 1991). Evaluating the

interference of common cocklebur

(Xanthium strumarium) and entire leaf of

morning glory (Ipomoea hederacea) on

soybean indicated that the crop LAI within

a given canopy stratum was smaller in

multi-species plots than those of soybeans

grown alone or with single weed species

and soybean plants also developed a large

proportion of their leaf area in the upper

portion of the canopy (Mosier & Oliver,

1995). Growth assessment of corn (Zea

mays L.) in monoculture and in

competition with Datura stramonium L.

showed faster growth of corn leaf area and

height reduced the photosynthetically

active radiation (PAR) received by the

weed. Corn had 70% and Datura

stramonium had 95% of its leaf area in the

upper half portion of the plant while weed

competition did not affect the canopy

architecture of corn (Cavero et al., 1999).

In the study of (Massinga et al., 2003),

palmer amaranth (Amaranthus palmeri)

LAI increased with increasing its density

from 0.5 to 8 plants.m-1. While at low plant

densities, 60% of palmer amaranth's leaf

area occurred between 0.5 and 1.5 m. As

plant density increased, 80% of the leaf

area was concentrated above 1 m.

Above-ground biomass is one of the

central traits in functional plant ecology

and growth analysis. It is a key parameter

in many allometric relationships (West et

al., 1999; Niklas & Enquist, 2002). The

vertical biomass distribution is considered

to be a main determinant determine of

competitive strength in plant species

(Schwinning & Weiner, 1998; Tackenberg,

2007). Many vegetation and yield variables

are potentially influenced by the

competition of the plant with a second crop

in an intercrop system and by competition

with other plants of the same species in

monocrop systems, all being affected by

changes of plant population density (PPD)

(Fortin et al., 1994). In monocrop systems,

soybean plants are more sparsely branched

at greater densities than at lower densities.

Soybean height, LAI and light interception

increased with increasing PPD (Boquet,

1990, Parvez et al., 1989; Foroutan-pour et

al., 1999).

Although yield variability in corn and

soybean intercrop systems has been the

focus of much research work (e.g. Hayder

et al., 2003; Egbo et al., 2004), there is

little information on vertical distribution of

leaf area and biomass in weed-crop

components of an intercropping system

(e.g. in corn-soybean mixed cropping).

Corn and Soybean Intercropping Canopy Structure … 41

Therefore, in this research we concentrate

on leaf area and biomass changes in the

mentioned crops and weeds.


The experiment was conducted at research

field of Tehran University (Karaj campus),

during the growing season of 2007. Soil

characteristics were clay-loam with 1.67%

organic matter, 0.093% total N, 46.67 ppm

P and 393.33 ppm K. Seedbed

preparations were a deep tillage in

previous autumn and two vertical diska

and leveller in spring. Fertilization was

done separately for each crop, in such a

manner 400 kg.ha-1 urea and 250 kg.ha-1

ammonium phosphate for the corn row,

applied in two stages, first split (200 kg) of

urea and whole phosphorus fertilizer, and

the second split of urea was applied at 6-8

leave stages. For soybean 150 kg.ha-1

ammonium phosphates with 50 kg.ha-1

urea were applied at early growing season.

No diseases and insect were observed.

Treatments were established in factorial

arrangement based on randomized

complete blocks design with three

replications. The treatments were five

different mixing ratios of corn (Zea mays

L.) and soybean (Glycine max L.)

including(corn/soybean): 100/0 (P1), 75/25

(P2), 50/50 (P3), 25/75 (P4) and 0/100 (P5)

Which were planted at four levels of weed

infestations: weed free (W1), infested to

redroot pigweed (Amaranthus retroflexus

L. AMRET) at 25 plant m-2 (W2), infested

to jimsonweed (Datura stramonium L.,

DASTR) at 25 plant m-2 (W3) and mixed

stands of redroot pigweed and jimsonweed

at total density of 25 plant m-2 (W4).

Each plot had 6 rows with 60 cm inter row

space and 6.5 m length. Corn (cv. K.SC.

500) and soybean (cv. Williams) were

planted on June 5th with arrangement of 20

* 60 cm and 25*60 cm for corn and

soybean respectively. The weed seeds

which were collected last year from the

research farm were kept at 4º C before

sowing, then simultaneously sown 15 cm

apart from crop rows at either two sides..

Weed seedlings were thinned to 15 plants

per row meter at two-leaf stage. All weed

species except of our target species were

thinned in two stages until 8 leaves of corn.

Field was irrigated with a seven days

interval.

At corn canopy closure (50% silking), a

vertical card board frame marked in 30-cm

increments was used in the field as a guide

to cut standing plants (both crops and

weeds) into 30-cm strata increments with

hedge shears (Mosier & Oliver, 1995). All

samples were transferred to the laboratory,

leaves and stem were separated and for

every sample the area of green leaves was

measured with a leaf area meter LICOR-

3000 A (LI-COR, Lincoln, NE, USA).

Afterwards all samples were oven-dried at

80 ºC for 72 hours and weighted. Both leaf

area and biomass were calculated as

percentage (%) in relation to whole plant.

At the end of growing season, all plants in

2 meters of 4 rows were harvested in each

plot, to evaluate the crop yield. The land

equivalent ratio (LER) gives an accurate

assessment of the greater biological

efficiency of the intercropping situation

and was calculated as equation (1):


Equation

(1): LER=(Yab/Yaa)+(Yba/Ybb)

LER = RYc +RYs

Where Yaa and Ybb are yields of sole

crops and Yab and Yba are yields of

intercrops. We considered RYc and RYs

as relative yield of corn and soybean

respectively. LER values greater than 1

were considered advantageous.


Corn Monoculture

In monoculture of corn the maximum leaf

area was 30.36% in weed free, while when

grown in presence of one or two weed

species, this index was higher (Figure 1 a,

b, c & d). Similar to other studies corn

allocated more leaf area to the upper layer

in presence of weeds. (Rajcan & Swanton,

2001 & Cavero et al., 1999). In sever

competitiveness (intra & inter specific

competition) there was no leaf area in layer

0-30 cm since plant ability to allocate

green shoot in upper layer is one of the

main traits therefore changing canopy

architecture is very important in

competition (Aerts, 1999). In corn infested

to DASTR, and DASTR + AMRET the

maximum leaf area of weeds was in layer

120-150 cm (Figure 1 f & g), while in corn

infested to AMRET, the maximum leaf area

(67.79%) was in layer 90-120 cm (Figure 1

e).

)a( (b) (c) (d)

(e) (f) (g)

Figure 1. LAI profiles of corn , A. retroflexus and D. stramonium in 100% corn: 0% soybean.

180-210

150-180

120-150

90-120

60-90

30-60

0-30

05101520253035

P1W1

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W2

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W3

180-210

150-180

120-150

90-120

60-90

30-60

0-30

05101520253035

P1W4

120-150

90-120

60-90

30-60

0-30

P1W2 0 10 20 30 40 50 60 70

120-150

90-120

60-90

30-60

0-30

020406080

P1W3

120-150

90-120

60-90

30-60

0-30

010203040506070

P1W4

0 10 20 30 40 50 60

Canopy layer (cm)

Canopy layer (cm)

Leaf area (%)

Leaf area (%)


The maximum amount of corn biomass

(42.7 & 42.96 %) in weed free and in

competition condition with AMRET were

established in layer 90-120 cm, but in corn

infested with DASTR and DASTR +

AMRET the maximum amount of corn

biomass (45.19 & 46.63%) was in layer

120-150 cm (Figure 2 a, b, c & d), which

could be for the reason of ear formation in

this layer.

Profiles of weeds biomass distribution in

these treatments showed that, when corn

competed with DASTR this weed also had

translocated the most percentage of

biomass to the highest layer (Figure 2 e).

This rate of biomass was for the reason of

formation of the most part of leaf area in

this layer. The main characteristics that

allowed this weed to compete against a

strong competitor such as corn was its

height plasticity, canopy architecture,

concentrated leaves in the upper part of the

plant, and higher light extinction

coefficient. An important feature is its

indeterminate growth habit, which allows

continuous increase in height (Stoller &

Wolley, 1985). This condition also, was in

both weed contamination (Figure 2 g). This

distribution pattern of biomass seems to be

for more radiation capturing.

(a) (b) (c) (d)

(e) (f) (g)

Figure 2. Biomass profiles of corn , soybean , A. retroflexus and D. stramonium in 100% corn: 0% soybean.

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W1

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W2

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W3

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P1W4

120-150

90-120

60-90

30-60

0-30

01020304050

P1W2

0 10 20 30 40 50

120-150

90-120

60-90

30-60

0-30

05101520253035

P1W3

120-150

90-120

60-90

30-60

0-30

05101520253035

P1W4

0 5 10 15 20 25 30 35

Canopy layer (cm)

Canopy layer (cm)

Biomass (%)

Biomass (%)


50% Corn: 50% Soybean Ratio

In weed free canopy of corn the greatest

leaf area (28.56%) was found in layer 90-

120 cm followed by layer 60-90 cm

which had less leaf area (27.75%) than

the above layer (Figure 3 a). which could

be concluded that in the absence of weed,

corn contributes its leaf area in lower

layers. When corn was grown with

AMRET, DASTR and both weed species,

more leaf area was established between

120-150 cm. In such conditions weeds can

not compete for light with crops.

Soybean in weed free unit had maximum

leaf area (43.68%) in layer 30-60 cm.

When grown with weed the maximum leaf

area were formed in layers 60-90, 90-120,

90-120 cm in plots which were infested to

AMRET, DASTR and AMRET+DASTR

(50.96, 37.57 and 37.30%) respectively.

Soybean plants developed a large

proportion of their leaf area in the upper

portion of the canopy, indicating their

competition for available light in the

canopy (Mosier & Oliver, 1995). In this

ratio, crops in weed infested treatments

expanded their leaf area and suppressed

weeds for radiation capture. Therefore it is

concluded that intercropping can be used

as a tool to improve competitive ability of

a canopy with good suppressive

characteristics. Planting patterns would

also provide better light distribution to

obtain higher biomass accumulation rates

and higher yields.

(b) (a) (c) (d)

(e) (f) (g)

Figure 3. LAI profiles of corn , soybean , A. retroflexus and D. stramonium in 50% corn: 50% soybean.

150-180

120-150

90-120

60-90

30-60

0-30

051015202530

P3W1

0 10 20 30 40 50

180-210

150-180

120-150

90-120

60-90

30-60

0-30

05101520253035

P3W2

0 10 20 30 40 50 60

180-210

150-180

120-150

90-120

60-90

30-60

0-30

05101520253035

P3W3

0 10 20 30 40

180-210

150-180

120-150

90-120

60-90

30-60

0-30

010203040

P3W4

0 10 20 30 40

90-120

60-90

30-60

0-30

P3W2 0 10 20 30 40 50 60 70 80

120-150

90-120

60-90

30-60

0-30

01020304050

P3W3

90-120

60-90

30-60

0-30

010203040506070

P3W4

0 10 20 30 40 50

Canopy layer (cm)

Canopy layer (cm)

Leaf area (%) in different treatments



In 50% corn: 50% soybean ratio, both

crops reach to a higher height to compete

with weeds (Figure 4 a, b, c & d) while

weeds could not compete well with crops,

because maximum biomass of DASTR and

AMRET in this treatment was formed in

layer 90-120 cm (Figure 4 e, f & g). A

faster growth of leaf area and height in

crops reduced the photosynthetically active

radiation (PAR) received by the weed and

consequently reduced weeds growth rate

(Cavero et al., 1999). Intercropped systems

are reported to use resources higher and

more efficiency than monocrop systems,

thus decrease the availability of resources

for weed production (Caruuthers et al.,

1998). In this ratio, crops can conquer

weeds and have good growth, with or

without weeds.

(a) (b) (c) (d)

(e) (f) (g)

Figure 4. Biomass profiles of corn , soybean , A. retroflexus and D. stramonium in 50% corn: 50% soybean. Soybean Monoculture:

Soybean in the weed free treatment,

expanded leaf area throughout the whole

canopy, but in weed infested plots it

allocated its leaf area to upper layers due to

inter specific competition (Figure 5 a, b, c,

& d). Soybean plants infested to DASTR

allocated its leaf area to layer 60-90 cm

(47.05 %) (Figure 4 c), which was lower

than the weed which shows that the weed

is a better competitor than soybean

specially when soybean grows by both

weeds species (Figure 5 c & d).

Soybean infested to AMRET had higher

leaf area in a lower layer than the weed (A.

retroflexus) meaning that when the

soybean grows in monoculture, it could not

suppress the weed and thus fewer yields,

but when it grown with corn, it could

suppress weeds due to the similar ability in

150-180

120-150

90-120

60-90

30-60

0-30

0102030405060

P3W1

0 10 20 30 40 50

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P3W2

0 5 10 15 20 25 30 35

180-210

150-180

120-150

90-120

60-90

30-60

0-30

0102030405060

P3W3

0 5 10 15 20 25 30

180-210

150-180

120-150

90-120

60-90

30-60

0-30

01020304050

P3W4

0 5 10 15 20 25 30

90-120

60-90

30-60

0-30

0510152025303540

P3W2

0 5 10 15 20 25 30 35 40

120-150

90-120

60-90

30-60

0-30

010203040

p3w3

90-120

60-90

30-60

0-30

0102030405060

p3w4

0 10 20 30 40

Canopy layer (cm)

Canopy layer (cm)

Biomass (%)

Biomass (%)


corn. Therefore in intercropping systems

crop partners use resource and grow

probably better than in monosulture

condition. For this reason they can

suppress weeds. The advantage that weeds

have over crops for light interception is

their height which is one of the best

predictions of competitive success in light

competition (Holt & Orcutt, 1991).

Graham et al., (1988) also observed that by

absorbing light in the upper canopy,

Palmer amaranth (Amaranthus palmeri)

and smooth pigweed (A. hybridus L.)

reduced light penetration into the sorghum

canopy. Effects of weed height on light

penetration through the crop canopy were

reported in competition studies between

velvetleaf (Abutilun theophrasti Medikus)

and soybean (Akey et al., 1990). although

Mosier & Oliver, (1995) reported that

soybeans grown alone/ monoculture of

soybean or with Ipomoea hederacea,

developed similar canopies and had similar

strata LAI values because Ipomoea

hederacea never acquired enough leaf area

or size to affect the soybean canopy with

irrigation.

(a) (b) (c) (d)

(e) (f) (g)

Figure 5. LAI profiles of soybean , A. retroflexus and D. stramonium in 0% corn: 100% soybean.

In weed free soybean biomass amounts of

upper layers of canopy were decreased due

to increasing height. This decrement in

30% upper layer was obvious. In non

competition condition, soybean tried to

have more branching which was caused in

lower layers of canopy therefore dry matter

accumulation was less in the upper layer.

Lack of weed interference for light

interception can be considered as an

acceptable reason for this event (Figure 10

60-90

30-60

0-30

P5W1 0 10 20 30 40 50

60-90

30-60

0-30

P5W2 0 10 20 30 40 50

60-90

30-60

0-30

P5W3 0 10 20 30 40 50

90-120

60-90

30-60

0-30

P5W4 0 10 20 30 40 50

90-120

60-90

30-60

0-30

P5W2 0 10 20 30 40 50

150-180

120-150

90-120

60-90

30-60

0-30

020406080

P5W3

120-150

90-120

60-90

30-60

0-30

020406080

P5W4

0 10 20 30 40 50 60

Canopy layer (cm)

Canopy layer (cm)


Leaf area (%)in different treatments


a). Investigation of biomass profiles of

soybean in competition with DASTR,

AMRET and DASTR+AMRET showed

that soybean changed biomass distribution

pattern (Figure 6 b, c & d) in such a

manner that higher amounts of biomass

were allocated to the upper layers (Figure 6

a, b, c & d). McLachlan et al., (1993)

suggested that lack of branching in high

density may lead to decreasing light

spectral quality as R/FR ratio. High plant

density decreased light penetration into the

canopy which can restrict stem branching

and lateral growth.

Changing the biomass profile in a crop

canopy is an important trait in the result of

competition and final crop yield. In three

way competition between soybean,

DASTR and AMRET, jimsonweed had

maximum biomass (38.29%) in 120-150

cm which was due to increased height and

more branching in the upper layers, while

redroot pigweed founded its maximum

biomass(45.17%) in layer 90-120 cm

(Figure 10 g).

The intensity of aboveground competition

experienced by soybean was expected to

increase from monoculture to

intercropping. The architecture of plant

affected the asymmetry of light

competition. Corn effectively suppresses

its neighbours with creating a deep shade

on them. But weeds interference may be

reduced by a combination of crop species

occupying two or more niches in the field.

Intercrops are more effective than sole

crops in conquering resources from weeds,

resulting to greater crop yield and less

weed growth.

(a) (b) (c) (d)

(e) (f) (g)

Figure 6. Biomass profiles of soybean , A. retroflexus and D. stramonium in 0% corn: 100% soybean.

60-90

30-60

0-30

0510152025303540

P5W1

0 5 10 15 20 25 30 35 40

60-90

30-60

0-30

01020304050

P5W2

0 10 20 30 40 50

60-90

30-60

0-30

01020304050

P5W3

0 10 20 30 40 50

90-120

60-90

30-60

0-30

05101520253035

P5W4

0 5 10 15 20 25 30 35

90-120

60-90

30-60

0-30

010203040

P5W2

0 10 20 30 40

150-180

120-150

90-120

60-90

30-60

0-30

0102030405060

P5W3

120-150

90-120

60-90

30-60

0-30

010203040

P5W4

0 10 20 30 40 50

Canopy layer (cm)

Canopy layer (cm)

Biomass (%)

Biomass (%)

48

Corn Yield

Corn/soybean mixing ratio and weed

infestation significantly affected corn grain

yield (P<0.001).The interaction effects was

also significant (P<0.01). The highest

amount of corn grain yield (9627.8 Kg ha1) was obtained in P2W1 treatment and

lowest amount (3916.5 kg ha

(Table 1 & Figure 1). Presence of both

weed species had the highest effect on corn

yield loss. Yield reduction in treatments of

low density corn (P4) has been contributed

to low number of plants and increased

weed competition ability for radiation

reception and probably higher efficiency of

weed roots for water and nutrient uptake.

In many intercropping experiments,

consisting legume and grass, intercr

had higher yield compare to monocropping

(Morris & Garrity, 1993). In a legume/cereal

intercropping, the nitrogen of the

associated crop may be improved by direct

Many researchers revealed that Leaf area

and vertical leaf area profile influence the

0

2000

4000

6000

8000

10000

12000

W1

a

c

d

corn

yie

ld (

Kg

/ h

a)

Figure 1. Interaction effect of mixing ratios and weed infestation on corn yield (W1): weed free, (W

to jimson weed and (W

: Corn pure stand

soybean

a

Aghaalikhani et al. (2009)/ Iranian Journal of Weed Science 5 (2)

Corn/soybean mixing ratio and weed

infestation significantly affected corn grain

yield (P<0.001).The interaction effects was

also significant (P<0.01). The highest

rn grain yield (9627.8 Kg ha-

treatment and

lowest amount (3916.5 kg ha-1) in P4W4

(Table 1 & Figure 1). Presence of both

weed species had the highest effect on corn

yield loss. Yield reduction in treatments of

has been contributed

to low number of plants and increased

weed competition ability for radiation

reception and probably higher efficiency of

weed roots for water and nutrient uptake.

In many intercropping experiments,

consisting legume and grass, intercropping

had higher yield compare to monocropping

In a legume/cereal

intercropping, the nitrogen of the

associated crop may be improved by direct

nitrogen transfer from the legume to cereal

(Banik et al., 2006). Legumes, with their

adaptability to different cropping patterns

and their ability to fix nitrogen, may offer

opportunities to sustain increased

productivity (Jeyabal & Kuppuswamy,

2001). Normally, productivity is

potentially enhanced by the inclusion of a

legume in a cropping

al., 2001). Legume intercrops are also

potential sources of plant nutrients that

complement inorganic fertilizers (Banik &

Bagchi, 1994; Banik et al.,

(2001) showed that yield and nutrient

uptake by intercropped wheat,

soybean were all significantly greater than

monocultures of wheat, maize and soybean

with the exception of potassium uptake by

maize. Intercropping advantages in yield

were 40-70% for wheat intercropped with

maize and 28-30% for wheat intercroppe

with soybean.

Many researchers revealed that Leaf area

and vertical leaf area profile influence the


radiation of corn canopy and consequently,

W2 W3 W4

b b b

aa a

c

cc

dd

d

. Interaction effect of mixing ratios and weed infestation on corn ): weed free, (W2): infested to redroot pigweed, (W3): infested

to jimson weed and (W4): infested to both weed species.

P1: Corn pure stand 75%corn, 25%soybean

P3: 50%corn, 50%soybean 25%corn, 75%soybean

a a

(2009)/ Iranian Journal of Weed Science 5 (2)

nitrogen transfer from the legume to cereal

2006). Legumes, with their

adaptability to different cropping patterns

and their ability to fix nitrogen, may offer

opportunities to sustain increased

productivity (Jeyabal & Kuppuswamy,

2001). Normally, productivity is

potentially enhanced by the inclusion of a

system (Maingi et

2001). Legume intercrops are also

potential sources of plant nutrients that

complement inorganic fertilizers (Banik &

et al., 2006). Li et al.,

(2001) showed that yield and nutrient

uptake by intercropped wheat, maize and

soybean were all significantly greater than

monocultures of wheat, maize and soybean

with the exception of potassium uptake by

maize. Intercropping advantages in yield

70% for wheat intercropped with

30% for wheat intercropped


radiation of corn canopy and consequently,

ba

. Interaction effect of mixing ratios and weed infestation on corn ): infested

P2: 75%

P4: 25%

Corn and Soybean Intercropping Canopy Structure

corn dry matter accumulation and grain

yield (Valentinuz & Tollenaar, 2006).

Soybean Yield

Both simple and interaction effects of

mixing ratios of corn/soybean and weed

infestation on soybean grain yield were

statistically significant (P<0.001). Results

indicated that in all weed infested

treatments, soybean monoculture had

higher yield than intercropped one (Table

2) mainly due to higher plant density.

Similarly in intercropped treatments yield

loss could be attributed to inter specific

competition. Indeed decremen

ratio in intercropping decreased soybean

grain yield because of intensified

competition.

Results showed that soybean has less

competitive ability than corn in

intercropping systems. According to

soybean growth nature, it used to allocate

It seems the weed compensated low

irradiance by increasing the specific leaf

area and partitioning more dry matter

initially to stems and later on to leaves

which increased the amount of

0

1000

2000

3000

4000

5000

6000

W1

b

a

soyb

ean

yie

ld (

Kg

/ha)

Figure 2. Interaction effect of mixing ratios to weed infestation on soybean yield. (W

(W3): infested to jimson weed and (W

soybean

soybean

Corn and Soybean Intercropping Canopy Structure …

matter accumulation and grain

yield (Valentinuz & Tollenaar, 2006).

Both simple and interaction effects of

mixing ratios of corn/soybean and weed

infestation on soybean grain yield were

statistically significant (P<0.001). Results

hat in all weed infested

treatments, soybean monoculture had

higher yield than intercropped one (Table

2) mainly due to higher plant density.

Similarly in intercropped treatments yield

loss could be attributed to inter specific

Indeed decrement of soybean

ratio in intercropping decreased soybean

grain yield because of intensified

Results showed that soybean has less

competitive ability than corn in

intercropping systems. According to

soybean growth nature, it used to allocate

part of its resources to symbiosis.

pigweed and jimsonweed

greatest soybean yield loss in different

ratios of intercropping. Simultaneous

infestation of AMRET and DASTR

more competitive ability with soybean than

one species infestation and caused

restricted number of pod per plant, grain

number per pod, 1000 grain weigh, and

finally caused yield reduction. Banik

(2006) confirm that higher grain yield of

monocropped wheat and chickpea relative

to intercropping treatments

the fewer disturbances in the habitat in

homogeneous environment of

monocropping systems. The Highest

amount of soybean grain yield (5050.0 kg

ha-1) was produced in P

while the lowest amount (365.67 kg ha

was observed in P2W4 (Table 2 & Figurer

2).

It seems the weed compensated low

irradiance by increasing the specific leaf

area and partitioning more dry matter

initially to stems and later on to leaves

ed the amount of

photosynthetically active area in

proportion to above – ground biomass, as

found when competing with soybean

(Regnier et al., 1988).

W W2 W3 W4

dd

d

cc

cc

b bb

a

aa

. Interaction effect of mixing ratios to weed infestation on soybean yield. (W1): weed free, (W2):infested to redroot pigweed,

): infested to jimson weed and (W4): infested to both weed species.

P2: 25%corn, 75%soybean : 50%corn, 50%soybean

P4: 75%corn, 25%soybean P5: soybean pure stand

… 49

of its resources to symbiosis. Redroot

infestations caused

greatest soybean yield loss in different

ratios of intercropping. Simultaneous

AMRET and DASTR have

more competitive ability with soybean than

estation and caused

restricted number of pod per plant, grain

number per pod, 1000 grain weigh, and

finally caused yield reduction. Banik et al.,

(2006) confirm that higher grain yield of

monocropped wheat and chickpea relative

to intercropping treatments may be due to

the fewer disturbances in the habitat in

homogeneous environment of

monocropping systems. The Highest

amount of soybean grain yield (5050.0 kg

) was produced in P5W1 treatment

while the lowest amount (365.67 kg ha-1)

(Table 2 & Figurer

photosynthetically active area in

ground biomass, as

found when competing with soybean

d

. Interaction effect of mixing ratios to weed infestation on ):infested to redroot pigweed,

): infested to both weed

P3:


Conclusion

According to our investigations from corn

and soybean grain yield at their

monocultures and intercrop, the highest

amount of Land Equivalent Ratio (LER)

(1.37) was observed in P3W1, which had

the lowest weed leaf area and biomass,

consequently suppressing weeds

successfully. Occupied different niches in

uptake of resources and reduced

competition mechanism resulted in

advantage for corn and soybean yield.

Neighboring of C4 (corn) and C3 (soybean)

species in all parts of growth stages not

only decreased competition, but also

increased facilitative mechanism (Table 1).

It is concluded that intercropping can be

used as a tool to improve competitive

ability of a canopy with good weed

suppressive characteristics. Studies using

species with growth forms similar to

soybean are therefore needed because since

this study suggests that the outcome of

intercropping is influenced by the

architectural and therefore size response of

intercropped species.

Table 1- Land Equivalent Ratio of corn and soybean intercropping.

Treatment RYc RYs LER P2W1 1.12 0.221 1.33 P2W2 1.029 0.203 1.23 P2W3 1.033 0.208 1.24 P2W4 0.928 0.192 1.12 P3W1 0.865 0.501 1.37 P3W2 0.662 0.458 1.12 P3W3 0.787 0.387 1.17 P3W4 0.775 0.365 1.14 P4W1 0.577 0.721 1.30 P4W2 0.477 0.712 1.19 P4W3 0.522 0.770 1.29 P4W4 0.425 0.762 1.19

REFERENCES

Aerts, R. 1999. Interspesific competition in natural

plant communities: Mechanisms, trade-offs

and plant-soil feedbacks. Journal of

Experimental Botany 50:29-37.

Akey, W. C., Jurrik, T. W. and Dekker. 1990.

Competition for light between a velvetleaf

(Abutillon theopharesti) and soybean (Glycine

max). Weed Research 30:403-411.

Banik, P. and Bagchi, D. K. 1994. Evaluation of

rice (Oryza sativa) and legume intercropping

in upland situation of Bihar plateau. Indian

Journal of Agriculture Science. 64: 364–368.

Banik, P., Midya, A., Sarkar, B. K. and Ghose, S. S.

2006. Wheat and chickpea intercropping

systems in an additive series experiment:

Advantages and weed smothering. European

Journal of Agronomy 24: 325–332.

Boedhram, N., Arkebauer, T. J. and Batchelor, W.

D. 2001. Season-Long Characterization of

Vertical Distribution of Leaf Area in Corn.

Agronomy Journal 93:1235–1242.

Boquet, D. J. 1990. Plant population density and

row spacing effects on soybean at post-optimal

planting dates. Agronomy Journal 82:59–64.

Carruthers, K., Cloutier, Fe. and Smith, D. L. 1998.

Intercropping corn with soybean, lupin and

forages: weed control by intercrops combined

with interrow cultivation. European journal of

Agronomy 8:225-238.


Cavero, J. Zaragoza, C., Suso, M. L. and Pardo, A.

1999. Competition between maize and Datura

sramonium in an irrigated field under semi-

arid conditions. Weed Research 39:225-240.

Egbo, C. U., Adagba, M. A. and Adedzwa, D. K.

2004. Responses of soybean genotypes to

intercropping with maize in the Southern

Gulinea Savanna, Nigeria. Acta Agronomica

Hungarica 52:157-163.

Foroutan-pour, K., Dutilleul, P. and Smith, D.

1999. Soybean canopy development as

Affected by population density and

intercropping with corn: Fractal Analysis in

Comparison with Other Quantitative

Approaches. Crop Science 39:1784–1791.

Fortin, M. C., Culley, J. and Edwards, M. 1994.

Soil water, plant growth, and yield of strip-

intercropping corn. Journal of Production

Agriculture 7:63–69.

Fortin, M. C. and Pierce, F. J. 1996. Leaf azimuth

in strip – intercropped corn. Agronomy Journal

88:6-9.

Graham, P. L., Steiner, J. L. and Weiese, A. F.

1988. Light absorption and competition in

mixed sorghum-pigweed communities.

Agronomy Journal. 80:415-418.

Hayder, G., Mumtaz, S. S., Khan, A. and Khan, S.

2003. Maize and soybean intercropping under

various levels of soybean seed rates. Asian

Journal of Plant Science. 2: 339-341.

Holt, J. S. 1995. Plant responses to light: a potential

tool for weed management. Weed Science

43:474–482.

Holt, J. S., Orcutt, D.R. 1991. Functional

relationships of growth and competitiveness in

perennial weeds and cotton (Gossypium

hirsutum). Weed Sci. Vol. 39: p.575-584.

Jeyabal, A. and Kuppuswamy, G. 2001. Recycling

of organic wastes for the production of

vermicompost and its response in rice–legume

cropping system and soil fertility. European

Journal of Agronomy 15: 153–170.

Li, L., Sun, J., Zhang, F., Li, X., Yang, S. and

Rengel, Z. (2001). Wheat/maize or

wheat/soybean strip intercropping, I. Yield

advantage and inter specific interactions on

nutrients. Field Crops Research. 71: 123-137.

Maingi, M. J., Shisanya, A.C., Gitonga, M. N. and

Hornetz, B. 2001. Nitrogen fixation by

common bean (Phaseolus vulgaris L.) in pure

and mixed stands in semi arid South east

Kenya. European of Journal of Agronomy 14:

1–12.

Massinga, R. A., Currie, R. S. and Trooien, T. P.

2003. Water use and light interception under

Palmer amaranth (Amaranthus palmeri) and

corn competition. Weed Science 51:523–531.

McLachlan, S. M., Tollenaar, M., Swanton, C. J.

and Weise, S. F. 1993. Effect of corn induced

shading on dry matter accumulation,

distribution, and architecture of redroot

pigweed (Amaranthus retroflexus). Weed

Science 41:568–573.

Morris, R. A. and Garrity, D. P. (1993). Resource

capture and utilization in intercropping: non-

nitrogen nutrients. Field Crops Research.34:

303-317.

Mosier, D. G. and Oliver, L. 1995. Common

Cocklebur (Xanthium strumonium) and

Entireleaf Morningglory (Ipomea hederacea

var. integriuscula) interference on soybean

(Glycine max). Weed Science 43:239-246.

Niklas, K. J. and Enquist, B. J. 2002. On the

vegetative biomass partitioning of seed plant

leaves, stems, and roots. American Naturalist

159:482–497.

Parvez, A. Q., Gardner, F. P. and Boote, K. J. 1989.

Determinate- and indeterminate-type soybean

cultivar responses to pattern, density, and

planting date. Crop Science. 29:150–157.

Rajcan, I. and Swanton, C. I. 2001. Understanding

maize-weed competition: resource

competition, light quality and whole plant.

Field crop Research. 71:139-150.

Regnier, E. E., Salvucci, M. E. and Stoller, E. W.

1988. Photosynthesis and growth responses to

irradiance in soybean (Glycine max) and three

broadleaf weeds. Weed Science 36:487-496.


Schwinning, S, Weiner, J. 1998. Mechanisms

determining the degree of size asymmetry in

competition among plants. Oecologia

113:447–455.

Sivakumar, M. V. K. and Virmani, S. M. 1984.

Crop productivity in relation to interception of

photosynthetically active radiation.

Agricultural and Forest Meteorology 31:131–

241.

Stoller, E. W. and Wooley, J. T. 1985. Competition

for light by broadleaf weeds in soybeans


Tackenberg, O. 2007. A New Method for non-

destructive measurement of biomass, growth

rates, vertical biomass distribution and dry

matter content based on digital image analysis.

Annals of Botany 99: 777–783.

Valentinuz, O. R. and Tollenaar, M. 2006. Effect

of genotype, nitrogen, plant density, and row

spacing on the area-per-leaf profile in maize.

Agronomy Journal 98:94–99.

West, G. B., Brown, J. H. and Enquist, B. J. 1999.

A general model for the structure and

allometry of plant vascular systems. Nature

400: 664–667.

Wiles, L. J. and Wilkerson, G. G. 1991. Modeling

competition for light between soybean and

broad leaf weeds. Agriculture System 35:37–

51.


چكيده

هاي هرز، بهتر چگونگي جذب نور بوسيلة گياهان زراعي و علف با توجه به نقش تعيين كننده ميزان سطح برگ در توزيع نور در داخل كانوپي، شناخت

به منظور بررسي اثر كشت مخلوط بر توزيع سطح برگ و ماده خشك گياهي در پروفيل كانوپي ذرت، سويا و . باشد مستلزم مطالعة ساختار كانوپي مي

3هاي كامل تصادفي با در قالب طرح بلوك كرج به صورت فاكتوريل در مزرعة پژوهشي دانشگاه تهران واقع در 1386علف هاي هرز، آزمايشي در سال

به صورت (.Glycine max L)و سويا (.Zea mays L)تيمار هاي آزمايشي شامل پنج سطح نسبت اختالط دو گونه گياه زراعي ذرت . تكرار انجام شد

هرز تاج چهار سطح آلودگي علفكشتي سويا بود كه در سويا و تك% 75: ذرت% 25سويا، % 50: ذرت% 50سويا،% 25: ذرت% 75كشتي ذرت، تك

خروس در عاري از علف هرز، آلوده به تاج: شامل (Datura stramonium L., DASTR)و تاتوره (Amaranthus retroflexus L. AMRET)خروس

كشتي ذرت و بدون نتايج نشان داد در تك .ر طول فصل كشت شدندتمام فصل، آلوده به تاتوره در تمام فصل و آلودگي توام به تاج خروس و تاتوره د

كه ذرت همراه با تاتوره يا هر دو گونه اما هنگامي. متري تشكيل شده بود سانتي 90-120از حداكثر سطح برگ گياه در اليه 36/30٪حضور علف هرز،

0-30در اليه ) از كل 66/34٪(كشتي سويا بيشترين ميزان زيست توده تكدر . هاي باالتر تشكيل شد علف هرز رشد كرد، حداكثر سطح برگ در اليه

تشكيل گرديد، در اين 60-90در اليه ) 97/32٪(باالترين ميزان (DASTR+AMRET) زمتري توليد شد، اما در زمان آلودگي با دو علف هر سانتي

هاي هرز رقابت نتوانست با علف تك كشتي سويا . متري تشكيل داد سانتي 120-150را در اليه ) 54/49٪(تيمار تاتوره بيشترين ميزان زيست توده خود

توانست با موفقيت باعث فرونشاني ، 50:50ذرت بويژه در نسبت اختالط/ اين در حالي است كه كشت مخلوط سويا. شد هاي هرز كند و مغلوب علف

- ذرت و سويا در كشت مخلوط، زمينه استفاده بهينه از نور خورشيد براي غلبه بر علف گرفت اثر مكملي توان نتيجه به اين ترتيب مي. هاي هرز شود علف

.هاي هرز و حفظ عملكرد را فراهم نموده است

لگوم/ ساختاركانوپي، توزيع سطح برگ، كشت مخلوط غله :كليدي كلمات

Iranian

Floristic Composition of Weed Community in Turfgrass Fields of Bajgah,

Department of Horticultural Science, College of Agriculture, Shiraz University, Shiraz, Iran

(Received 16 Decemb

ABSTRACT

A weed survey of turfgrass fields was conducted at Bajgah during 2008

fields had been covered with Sport turf. Quantitative measurements viz frequency (F), field

uniformity (FU), mean field density (MFD), mean occurrence field density

relative abundance (RA) were recorded. Fourteen species of weeds of 9 families were

recorded. Most of them were included in Asteraceae, Fabaceae, Poaceae, and Plantaginaceae.

The most important broad leaved and narrow

Cynodon dactylon [L.] Pers., respectively. Results indicated that the highest frequency (F)

(100%), field uniformity (FU) (89.28%), mean field density (MFD) (58.43 m

occurrence field density (MOFD) (58.43 m

Results were almost the same at year 2009.

relative abundance in both years.

Key words: Lawn, population, survey,



Floristic Composition of Weed Community in Turfgrass Fields of Bajgah, Iran

S. Esmaili and H. Salehi*


Received 16 December 2009; returned 10 June 2010; accepted 6 December 2010)

A weed survey of turfgrass fields was conducted at Bajgah during 2008- 2009. The turfgrass


uniformity (FU), mean field density (MFD), mean occurrence field density



The most important broad leaved and narrow-leaved weeds were Taraxacum

[L.] Pers., respectively. Results indicated that the highest frequency (F)

(100%), field uniformity (FU) (89.28%), mean field density (MFD) (58.43 m

occurrence field density (MOFD) (58.43 m-2) belongs to T. officinale L. of the year 2008.

Results were almost the same at year 2009. Taraxacum officinale L. showed the highest

relative abundance in both years.

Lawn, population, survey, Taraxacum officinale L., weeds.

[email protected]

Floristic Composition of Weed Community in Turfgrass Fields of Bajgah,


2009. The turfgrass


uniformity (FU), mean field density (MFD), mean occurrence field density (MOFD) and



Taraxacum officinale L. and

[L.] Pers., respectively. Results indicated that the highest frequency (F)

(100%), field uniformity (FU) (89.28%), mean field density (MFD) (58.43 m-2) and mean

L. of the year 2008.

L. showed the highest

56 Esmaili and Salehi (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Turfgrass has been widely used by humans

as soil covers for more than ten centuries

(Beard, 1994). Lawn and turfgrasses are

important for functional, recreational and

ornamental uses (Beard, 1998). In turf

area, weeds are the major problem, which

can be often the result of improper and

inappropriate management (Uddin et al.,

2009). Weeds compete with turfgrasses for

light, soil nutrients, available water and

physical space. They are also hosts for

pests such as plant pathogens, nematodes

and insects. Certain weeds are also irritants

to humans as allergic reactions of pollen or

chemicals. Turfgrasses have attractive

green color, texture, density and uniformity

(Emmons, 2000). Turf weeds may be

grasses, grass-like plants (rushes or

sedges), or broadleaf plants with annual,

biennial, and/or perennial life cycles

(Bennet, 2004). Therefore, to enrich

aesthetic quality of turf, weeds must be

eliminated from turfgrass area. However,

in any place a plant community is rarely

homogenous as to the species and

distribution (Kim & Moody, 1980).

Whenever weeds appear in a turfgrass

community, proper identification of the

weed species is essential before

economical and effective management

practices (Dernoeden, 1999). Therefore,

weed surveys are useful for determining

the occurrence and importance of weed

species in any production systems as well

as turf area (Thomas, 1985; McCully et al.,

1991; Frick & Thomas, 1992; McClosky et

al., 1998). The objective of this study was

to determinate density, frequency, and

uniformity of weeds and weed prevailing

species in climatic condition of Bajgah,

Shiraz. There are many weed species with

similar morphology to turfgrass, therefore,

it is important to identify the species

correctly and decide upon the practical

weed control methods.


A survey study was conducted in turfgrass

fields of the Shiraz College of Agriculture,

Shiraz University, Iran, located at Bajgah

(1810 m above the mean sea level, 52° 32'

E and 29° 36' N). Average maximum and

minimum temperatures are 38 °C and –9

°C, respectively with the annual rainfall of

400 mm (Salehi & Khosh-Khui, 2004).

The turf fields had been covered with sport

turf (25% Lolium perenne 'Esquire', 30%

Lolium perenne 'Keystone', 10%, Festuca

rubra 'Maxima 1', 15% Poa pratensis

'Balin' and 20% P. pratensis 'Sobra').

Seven fields were selected randomly and

samplings were performed in 0.5×0.5 m2

plots (Figure 1), four samples from each

plot. All weeds in each plot were

identified, counted and recorded. Data

were summarized using five quantitative

measurements as outlined by Thomas

(1985); frequency (F), field uniformity

(FU), density (D), Mean field density

(MFD), Mean occurrence field density

(MOFD) and relative abundance (RA).

Frequency (F) was calculated as the

percentage of the total number of fields

surveyed in which a species occurred in at

least one quadrate.

Floristic Composition of Weed Community in Turfgrass … 57

Figure 1. A scene of dominant weeds in a turfgrass field.

100

7

1 ×∑

=n

Yi

Fk

where F k = frequency value for species k

Yi = presence (1) or absence (0) of species

k in field i

n = number of fields surveyed.

Field uniformity was calculated as the

percentage of the total number of quadrates

sampled in which a species occurred.

1007

1

7

1 ×∑∑

=n

nXij

FUk

where FU k = field uniformity value for

species k

X ij = presence (1) or absence (0) of

species k in quadrate j in field i


The field density (D) of each species in a

field which was calculated as:

Ai

Zi

Dki

∑

=

7

1

where =Dki density (in numbers m-2) value

of species k in field i

Zi = number of plants of a species in

quadrate j (0.25 m2)

Ai = area i ( m2) of 20 quadrates in field i.

Mean field density (MFD):

n

nDki

MFDk

∑

= 1

where MFDk = mean field density of

species k

Dki = density (in numbers m-2) of species k

in field i


Mean occurrence field density (MOFD):

an

nDki

MOFDk −

∑

= 1

where MOFDk = mean occurrence density

of species k


Dki = density (in numbers m-2) of species

k in field i

n = number of fields surveyed

a = number of fields from which species k

is absent.

Relative abundance (RA) was used to rank

the weed species in the survey and it was

assumed that the frequency, field

uniformity and mean field density

measures were of equal value in describing

the relative importance of a weed species.

This value has no units but the value for

one species in comparison to another

indicates the relative abundance of the

species (Thomas & Wise, 1987). The

relative frequency (RF), relative field

uniformity (RFU) and relative mean field

density (RMFD) was calculated as:

Relative frequency for species k (RFk ):

=RFkspeciesallforvaluesfrequencyofSum

kspeciesofvalueFrequency 100×

Relative field uniformity for species k (RFUk ):

100×=speciesallforvaluesuniformityfieldofSum

kspeciesofvalueuniformityFieldRFUk

Relative mean field density for species k

(RMFDk):

100×=speciesallforvaluesdensityfieldmeanofSum

xkspeciesofvaluedensityfieldMeanRMFDk

The relative abundance of species k (RAk )

was calculated as the sum of relative

frequency, relative field uniformity and

relative mean field density for that species;

RMFDkRFUkRFkRAk ++=

Relative abundance is an index that was

calculated using a combination of

frequency, field uniformity and field

density for each species, as described by

Thomas (1985).

RESULTS AND DISCUTION

In the present survey on weed communities

of turf fields in the College of Agriculture,

Shiraz University, 14 weed species from 9

plant families were identified. Most of the

weed species were included in the

Fabaceae family (Table1). However,

Asteraceae had the most frequency (F),

uniformity (UF), mean field density

(MFD) and mean occurrence density

(MFOD) (Tables 1, 2, 3). In our study,

21.42% of observed weeds were classified

as annuals, and 78.57% as perennials

(Table 1).


Table 1. Distribution of observed weed species based on family and life cycle.

Familiy Scientific name Common name Life cycle Poaceae Cynodon dactylon [L.] Pers. Common bermudagrass Perennial

Asteraceae Lactuca scariola L. Prickly wield lettuce Annual Taraxacum officinale L. Common dandelion Perennial

Fabaceae Medicago sativa L. Alfalfa Perennial Medicago lupulina L. Black medic Annual/Perennial Trifolium repens L. Red clover Perennial

Malvaceae Malva neglecta Wallroth Common mallow Biennial/Perennial

Plantaginaceae Plantago lanceolata L. Buckhorn plantain

Herbaceous perennial

Plantago major L. Common plantain Herbaceous Perennial

Chenopodiaceae Chenopodium album L. Common lambsquarter Annual

Convolvulaceae Dichondra repens L. Kidney grass Perennial Convolvulus arvensis L. Field bin weed Perennial

Rubiaceae Galium aparine L. Cleavers Herbaceous annual Ulmaceae Ulmus minor Mill. Elm Perennial

In both years, the highest frequency

belonged to Taraxacum officinale from the

Asteraceae family (Tables 2 & 3). T.

officinale is clearly the most important and

abundant weed in turfgrass fields, known

as a perennial plant that has deep roots if

propagated via seeds. T. officinale seeds

disperse by wind. The growth of weed

species in different areas is influenced by

several factors. For example, Xing et al.,

(2000) reported 74 weed species belonging

to 24 families in turfgrass lands in

Hangzhou, China. In a floristic survey in

Brazil on Paspalum notatum Flugge

cultures under sun light and shadow of

tree canopy, 45 weed species belonging to

15 families were observed, among which

Asteraceae, Poaceae, Cyperaceae,

Euphorbiaceae and Fabaceae had the major

species (Maciel et al., 2008). However, in

our investigated fields the most weed

species belonged to Fabaceae, Asteraceae,

Convolvulaceae and Plantaginaceae. In the

present survey number of perennial weed

species was higher than annual weeds.

Similarly, Al-Gohary (2008) reported that

perennial weeds were more than annual

weeds in eleven lands of Gebel Elba

districts in Egypt.


Table 2- Frequency (F), field uniformity (FU), mean field density (MFD), and mean occurrence field density

(MOFD) of weeds in turfgrass fields in the first year.

Scientific name F (%) FU (%) MFD (m-2) MOFD (m-2) Taraxacum officinale L. 100.00 89.28 58.43 58.43 Medicago sativa L. 71.43 35.71 6.71 11.75 Medicago lupulina L. 57.14 28.57 8.428 14.75 Ulmus minor Mill. 42.86 17.86 3.14 7.33 Trifolium repens L. 71.43 28.57 13.85 22.00 Malva neglecta Wallroth 14.28 3.57 0.14 1.00 Plantago lanceolata L. 57.14 25.00 1.14 2.00 Plantago major L. 71.43 35.71 1.71 2.40 Chenopodium album L. 14.28 3.57 0.14 1.00 Lactuca scariola L. 14.28 3.57 0.43 3.00 Dichondra repens L. 28.57 10.71 8.00 28.00 Convolvulus arvensis L. 28.57 7.14 0.71 2.50 Galium aparine L. 28.57 10.71 2.43 8.50 Cynodon dactylon [L.] Pers. 71.43 35.71 18.14 25.40

Table 3. Frequency (F), field uniformity (FU), field density (MFD), and mean occurrence field density (MOFD)

of weeds in turfgrass fields in the second year.

Scientific name F (%) FU (%) MFD (m-2) MOFD (m-2) Taraxacum officinale L. 100.00 82.14 86.86 80.57 Medicago sativa L. 57.14 42.86 17.57 30.75 Medicago lupulina L. 85.71 42.86 6.57 11.50 Ulmus minor (Mill.) 57.14 28.57 6.14 10.75 Trifolium repens L. 71.43 42.86 54.86 76.80 Malva neglecta Wallroth - - - - Plantago lanceolata L. 57.14 14.28 0.71 1.25 plantago major L. 57.14 35.71 1.71 3.00 Chenopodium album L. - - - - Lactuca scariola L. - - - - Dichondra repens L. 28.57 7.14 5.00 17.50 Convolvulus arvensis L. - - - - Galium aparine L. 28.57 14.28 4.71 16.50 Cynodon dactylon [L.] Pers. 71.43 39.28 19.43 27.20

Uniformity is a quantitative measure of the

spread of a weed species within a given

field. For example, T. officinale, Medicago

sativa, Plantago major, Cynodon dactylon,

M. lupulina, Trifolium repens, and P.

lanceolata were uniformly distributed

throughout the fields (Table 2). In the first

year, T. officinale was the most abundant

weed with a density of 58.43 plants m-2. In

the second year, T. officinale and T. repens

were the most abundant weeds with 86.8

and 54.86 plants m-2, respectively.

Results of the experiment is similar to the

report by Ghorsi-Anbaran et al., (2006)

who observed that the highest frequency

belonged to Asteraceae in grasslands of

Mashhad.


Younesabadi et al., (2006) observed that

Poaceae, Brassicaceae and Fabaceae had

the highest Relative abundance (RA) in

Golestan province and showed that 82% of

the observed weeds were annual and the

remaining were perennial. Furthermore,

87% of weeds were dicotyledonous and

13% were monocotyledonous. Phalaris

minor Retz., Melilitus officinalis (L.) Lam.,

Avena ludoviciana Durieu., Veronica

persica Poir., Brassica sp., Polygonum

aviculare L. and Sinapis arvensis L. had

the highest abundance in Golestan

province. In our study, the highest RA

belonged to weed species including: T.

officinale, C. dactylon, M. lupulina, T.

repens, and M. sativa. The RA values for

these weed species were 99.39, 41.17,

39.31, 35.01, and 26.72, respectively

(Table 2). The RA values of T. officinale

were the highest in both years reflecting its

respective highest values of frequency (F),

field uniformity (FU) and mean field

density (MFD) (Tables 2, 3, 4, 5).

Table 4. Relative abundance (RA) of weeds that occurred in seven fields in the first year.

Scientific name RA Taraxacum officinale L. 99.39 Medicago sativa L. 26.72 Medicago lupulina L. 39.31 Ulmus minor Mill. 16.94 Trifolium repens L. 35.01 Malva neglecta Wallroth 4.03 Plantago lanceolata L. 20.46 plantago major L. 12.77 Chenopodium album L. 4.03 Lactuca scariola L. 4.27 Dichondra repens L. 15.81 Convolvulus arvensis L. 8.42 Galium aparine L. 11.14 Cynodon dactylon [L.] Pers. 41.17

Table 5. Relative abundance (RA) of weeds that occurred in seven fields in the second year.

Scientific name RA Taraxacum officinale L. 82.41 Medicago sativa L. 30.18 Medicago lupulina L. 29.43 Ulmus minor Mill. 20.48 Trifolium repens L. 50.82 Malva neglecta Wallroth - Plantago lanceolata L. 20.35 plantago major L. 20.35 Chenopodium album L. - Lactuca scariola L. - Dichondra repens L. 9.15 Convolvulus arvensis L. - Galium aparine L. 11.05 Cynodon dactylon [L.] Pers. 32.39


Uddin et al., (2009) stated that Cyperus

aromaticus (Ridley) Mattf & Kuk and

Fimbristylis dichotoma (L.) Vahl are the

most important two sedges in turfgrass

areas. Two grass Ischaemum indicum

(Houtt.) Merr., Chrysopogon aciculatus

(Retz.) Trin. and two broadleaves

Desmodium triflorum (L.) DC. and

Borreria repens DC. were equally

important and abundant species containing

frequency ≥50% and RA value ≥ 12.

Diversity of weed species depended on

different factors such as soil structure, pH,

nutrients and water, crop type, weed

control methods and field history

especially in local geographical variation

(Kim et al., 1983). Furthermore, diversity

of weed communities will determine the

nature of weed management strategies

required and changes in diversity may be

indicative of potential weed management

problems (Derksen et al., 1995).

Relative abundance provides an indication

of the overall weed problem posed by an

species (Uddin et al., 2009). Overall, the

weed species of turf are those that are

adapted in some way to the continuous

defoliation experienced in a turf field and

well-adequate in that environment.

However, the ranking of weed species

differed in the lists based on frequency (F),

field uniformity (FU) and mean field

density (MFD) but, within the weed type

(Uddin et al., 2009).

Generallly, T. officinale belonging to the

Asteraceae family was the most abundant

weed in turfgrass fields followed by T.

repens, M. sativa, M. lupulina and C.

dactylon [. This information would be

important for further studies in the same

fields and for the best integrated pest

management (IPM) programs.

REFERENCES

Al-Gohary, I. H. 2008. Floristic composition of

eleven wadis in Gebel Elba, Egypt.

International Journal of Agriculture and

Biology 10: 151–160.

Beard, J. B. 1998. The Benefits of golf course turf.

pp: 191-201. Golf Course Management,

March.

Beard, J. B. and Robert, L. G. 1994.The role of

turfgrasses in environmental protectionand

their benefits to Humans. Journal of

Environmental Quality 23: 452-460.

Bennet, S. T. 2004. Suggestions for the care of

Seashore Paspalum. Retrieved August

10,2007from

http://www.environmentalturf.com/images/mai

ntenace/finalmanual.pdf.

Derksen, D. A., Thomas, G. J., Lafond, G. P.,

Loeppky, H. A. and Swanton, C. J. 1995.

Impact of post-emergence herbicides on weed

community diversity within conservation-

tillage systems. Weed Research 35: 311–320.

Dernoeden, P. H. 1999. Agronomy Mimeo 79:

Broadleaf weed control in established lawns.

Retrieved October 12, 2009, from

http://iaa.umd.edu/umturf/Weeds/Broadleaf_C

ontrol.html. (Accessed 12 October 2009)

Emmons, R. D. 2000. Turf grass science and

management, 3rd edition. NewYork: Delmar,

Thompson Learning, Inc. New York.

Frick, B. and Thomas, A. G. 1992. Weed surveys in

different tillage systems in southwestern

Ontario field crops. Canadian Journal of Plant

Science 72: 1337–1347.

Ghorsi- anbaran, A. R., Bazoobandi, M., Arian, H.

and Mousavi – Sarveneh Baghi, R. 2007.

Floristic studies in landscapes and urban parks

of Mashhad. The proceedings of 2th Iranian

Weeds Conference. 18-22.(In Persian with

English summary).


Kim, S. C., Park, R. K. and Moody, K. 1983.

Changes in the weed flora transplanted rice as

affected by introduction of improve rice

cultivarsand the relationship between weed

communities and soil chemical properties.

Research Report ORD.25: 90–97.

Kim, S. C. and Moody, K. 1980. Types of weed

communities in transplanted lowland rice and

relationship between yield and weed weight in

weed communities. Journal of Korean Society

for Crop Science 25: 1–8.

Maciel, C. D. G., Poletine, J. P., Aquino, C. J. R.,

Ferreira, D. M. and Maio, R. M. D. 2008.

Floristic composition of the weed community

in Paspalum notatum flügge turf grasses in

Assis, sp. Planta Daninha Viçosa-MG 26: 57–

64.

McClosky, W. B., Baker, P. B. and Sherman, W.

1998. Survey of cotton weeds and weed

control practices in Arizona upland cotton

fields. p. 7 in J. Silvertooth (Ed.). Cotton: a

College of Agriculture, University of Arizona.

McCully, K. V., Sampson, M. G. and Watson, A.

K. 1991. Weed survey of Nova Scotia low

bush blueberry (Vaccinium angustifolium)

fields. Weed Science 29: 180–185.

Thomas, A. G. 1985. Weed survey system used in

Saskatchewan for and oilseed crops. Weed

Science 33: 34–43.

Thomas, A. G. and Wise, R. F. 1987. Weed survey

of Saskatchewan cereal and oilseed crops

1986. Weed Survey Series Publ. 87-1,

Agriculture Canada, Regina, SK. 251p.

Uddin, M. K., Juraimi, A. S., Begum, M., Ismail,

M. R., Rahim, A. A. and Othman, R. 2009.

Floristic composition of weed community in

turf grass area of West Peninsular Malaysia.

International Journal of Agriculture and

Biology 11: 13-20.

Xing, A. C., Qiang, W., Ping, Z. A., Fen, D. and

Ming, L. X. 2000. Survey of weeds in turf in

Hangzhou. Acta Agriculturae. Zhejiangensis

12: 360–362.

Younesabadi, M., Salimi, H. and Kashiri, H. 2007.

Identification and determination of density,

frequency and uniformity of dominant weeds

of canola in Golestan Province. The

proceedings of 2th Iranian Weeds Conference.

23-27.(In Persian with English summary).


چكيده

زمين هاي در . انجام شد 1387-1388علف هاي هرز زمين هاي چمن در دانشكده كشاورزي، دانشگاه شيراز در باجگاه در دو سال متوالي بررسي از

، ميانگين )FU(، يكنواختي زمين )F(اندازه گيري هاي كمي مانند فراواني . از هر زمين صورت گرفتنمونه گيري پوشش يافته، چمن با چمن اسپورت

تيره گياهي ثبت 9چهارده گونه علف هرز متعلق به . ثبت شدند (RA)فراواني نسبي و (MOFD)زمين م، ميانگين وقوع تراك(MFD)تراكم زمين

ترين علف هاي هرز پهن برگ و باريك برگ، به ترتيب مهم. سانان، فريژسانان و بارهنگ سانان مي باشندمينا سانان، باقال : اكثر آن ها شامل. گرديد

-m ( MFD)(ميانگين تراكم زمين ،%)FU()28/89(، يكنواختي زمين %)100( (F) نتايج نشان داد كه بيشترين فراواني. گل قاصد و چاير مي باشند

مشابه سال تقريباً 1388سال نتايج . مي باشد 1387متعلق به گل قاصد در سال %) m-243/58( MOFD) (ميانگين وقوع تراكم زمينو%) 243/58

.گل قاصد باالترين فراواني نسبي را در هر دو سال نشان داد. بود 1387

هاي هرزچمن، جمعيت، بررسي، گل قاصد، علف: كليدي كلمات

Iranian Journal

Ability of Adjuvants in Enhancing the Performance of Pinoxaden and Clodinafop Propargyl Herbicides against Grass Weeds

A. Mousavinik1, E. Zand1, M.

1 Department of Weed Research, Iranian Plant Protection Research Institute, Tehran, Iran.2 Department of Agroecology, Environmental Sciences Research Institute, Shahid Beheshti University, Tehran,

Iran.3 Fars Agricultural and Natural Resources Research CeFaculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

(Received 11 December 2010; returned 25 April 2010; accepted 6 December 2010

ABSRTACT

Adjutants' ability in enhancing the performance of h

research. To identify an appropriate adjuvant for pinoxaden and clodinafop propargyl

herbicides against littleseed canarygrass (

fatua L.) and ryegrass (Lolium temulentu

under greenhouse conditions. In all experiments treatments consisted of five doses of

pinoxaden and two doses of each of the three commercial formulations of clodinafop

propargyl (Topik, Behpik & Karent), wi

Citohef and Volk. Performance of all herbicides increased with enhancing their

concentrations against the tested plants except for clodinafop propargyl in case of wild oat.

The addition of Volk (followed by Ad

against ryegrass and littleseed canarygrass, supporting the idea that either Volk or Adigor

solubilizes the cuticular waxes thus facilitating their uptake. Adding Volk and Adigor had the

highest and lowest influence on pinoxaden performance against wild oat, respectively.

Totally, the adjuvant receptivity for pinoxaden was higher than for clodinafop propargyl.

Between the two surfactants, Citogate was more effective than Citohef in enhancing the

efficacy of pinoxaden against ryegrass and littleseed canarygrass, while, Citohef was more

effective in increasing the efficacy of pinoxaden against wild oat.

Key words: adjuvant, clodinafop propargyl, littleseed canarygrass, pinoxaden, ryegrass, wild

oat.

Corresponding author: E-mail: eszand@yahoo


bility of Adjuvants in Enhancing the Performance of Pinoxaden and Clodinafop Propargyl Herbicides against Grass Weeds

. A. Baghestani1, R. Deihimfard2, S. Soufizadeh

Aliverdi4

Department of Weed Research, Iranian Plant Protection Research Institute, Tehran, Iran.Department of Agroecology, Environmental Sciences Research Institute, Shahid Beheshti University, Tehran,

Fars Agricultural and Natural Resources Research Center, Shiraz, Fars,4 Department of Agronomy, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

(Received 11 December 2010; returned 25 April 2010; accepted 6 December 2010)

Adjutants' ability in enhancing the performance of herbicides is a major priority in adjuvant


herbicides against littleseed canarygrass (Phalaris minor Retz.), common wild oat (

Lolium temulentum L.), three separate experiments were conducted



propargyl (Topik, Behpik & Karent), with and without the adjuvants Adigor, Citogate,



The addition of Volk (followed by Adigor) had the highest effect on pinoxaden efficacy



influence on pinoxaden performance against wild oat, respectively.



pinoxaden against ryegrass and littleseed canarygrass, while, Citohef was more

effective in increasing the efficacy of pinoxaden against wild oat.

adjuvant, clodinafop propargyl, littleseed canarygrass, pinoxaden, ryegrass, wild


bility of Adjuvants in Enhancing the Performance of Pinoxaden and Clodinafop Propargyl Herbicides against Grass Weeds

Soufizadeh2, F. Ghezeli3, A.

Department of Weed Research, Iranian Plant Protection Research Institute, Tehran, Iran. Department of Agroecology, Environmental Sciences Research Institute, Shahid Beheshti University, Tehran,

Department of Agronomy, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

)

erbicides is a major priority in adjuvant


Retz.), common wild oat (Avena

L.), three separate experiments were conducted



th and without the adjuvants Adigor, Citogate,



igor) had the highest effect on pinoxaden efficacy



influence on pinoxaden performance against wild oat, respectively.



pinoxaden against ryegrass and littleseed canarygrass, while, Citohef was more

adjuvant, clodinafop propargyl, littleseed canarygrass, pinoxaden, ryegrass, wild

66 Mousavinik et al. (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Winter wheat is one of the most important

cereals in Iran. Annual grasses such as

ryegrass, littleseed canarygrass, and wild

oat reduce yield through competing for

resources such as water, nutrient and light

(Baghestani et al., 2007). The acetyl

coenzyme-A carboxylase (ACCase)

inhibiting herbicides, are the most effective

and widespread method to control the

above-mentioned weeds in Iran

(Baghestani et al., 2008) which might

result in evolution of resistance in grasses

due to high selective pressure imposed by

this group of herbicides (Devine &

Shimabukuro, 1994). Moreover,

environmental side-effects due to high

usage of the ACCase inhibitors are

probable (Rashed-Mohassel et al., 2010).

A solution to the above-mentioned

negative impacts of continuous application

of ACCase herbicides is to use adjutants

and/or surfactants. These chemical

compounds decrease the application dose

of herbicides (Sharma & Singh, 2000).

Adjuvants (e.g. methylated seed oils

(Sharma & Singh, 2000) and surfactants

(Rashed-Mohassel et al., 2009)) can reduce

the surface tension of spray solution;

thereby increase the chance of spray

droplets to sit on the plant surface.

Moreover, they can increase the droplets

spread on leaf surface and enhance the

foliar activity of post-emergence

herbicides (Rashed-Mohassel et al., 2009)

due to an increase in the infiltration rate of

the active ingredient into the cuticular

waxes. There are many factors that affect

the suitability of an adjuvant (Green &

Foy, 2000; Zolinger, 2000). Based on their

type, adjuvant can directly/indirectly affect

the formulations efficacy-related factors

including atomization, deposition,

retention, absorption and translocation

(Zabkiewicz, 2000). Many researchers

have stated that adjuvant performance

depends on the interaction among

herbicide, adjuvant and plant surface

characteristics (Bunting et al., 2004a

;Rashed-Mohassel et al., 2010).

The objective of the present research was

to test and determine the ability of four

different adjuvants in increasing the

performance of pinoxaden and clodinafop

propargyl against ryegrass, little seed

canarygrass, and wild oat.


Plant Materials

The seeds of ryegrass, little seed

canarygrass, and wild oat were obtained

from The Department of Weed Research at

Iranian Plant Protection Research Institute,

Tehran. The seeds were placed in Petri

dishes in an incubator at alternating

temperatures of 20/15°C and relative

humidity of 45/65% under 16/8 hour light

and dark cycle. After germination, six

seedlings with uniform radical length (8-10

mm) were selected and planted 1 cm deep

in 1.5 L plastic pots that were filled with a

mixture of soil, peat, vermiculate, and sand

(3:2:2:2 v/v/v/v). The pots were placed and

kept in a greenhouse with a light/dark

period of 16/8 hour at 25/15°C. A lamp

was used to supply additional light and

extend the day length. The plants were

irrigated every three days and thinned to

four per pot at one-leaf stage.

Ability of Adjuvants in Enhancing the Performance … 67

Chemicals, Treatments and Measurements

Separate experiments were established for

each weed species in a completely

randomized design with a factorial

arrangement of treatments and six

replications. Factor A was different

herbicides including Pinoxaden EC 10% at

30, 40, 50, 60 and 70 g a.i. ha-1, and three

commercial formulations of clodinafop

propargyl EC 8% including Topik, Behpik

and Karent, each at 48 and 64 g a.i. ha-1

applied against ryegrass, littleseed

canarygrass, and wild oat. Factor B was

using and not-using herbicides with the

following adjuvants: (i) Adigor (a

methylated seed oil, 44.8 % methylated

rapeseed oil and 28.2 % ethoxylated

alcohols, Syngenta, Switzerland); (ii )

Citogate (a non-ionic surfactant, 100%

alkylarylpolyglycol ether, Zarnegaran Pars

Company, Karaj, Iran); (iii ) Citohef (a

non-ionic surfactant, 100%

alkylarylpolyglycol ether, Hef Chemicals

Company, Semnan, Iran); and (iv) Volk

(petroleum oils, 80% EC, 800 g a.i. L-1

petroleum oils, associated with 200 g a.i.

L-1 emulsifier, Melli Agrochemical

Company, Alborz Industrial City, Ghazvin,

Iran). All adjuvants were applied at 2 %

(v/v). Herbicides were sprayed at three- to

four-leaves stage by using a sprayer

equipped with a Flat-fan nozzle, delivering

300 L spray solution ha-1 at 250 kPa.

Thirty days after spraying, the number of

survived plants per pot was recorded and

the fresh and dry (dried at 70°C for 48

hours) above-ground biomass in each pot

were measured. In addition, two days prior

to harvest, assessment of visual weed

control was conducted according to

European Weed Research Council

(EWRC) scoring on a scale of 1 to 9

representing 100%, 99-98%, 97-95%, 94-

90%, 89-82%, 81-70%, 69-55%, 54-30%

and 29-0.00% injury, respectively (Sandral

et al., 1997). The data was subjected to

analysis of variance using the GLM

procedure in SAS (SAS Institute Inc.,

2000). A physical slicing was performed

due to significant interaction between

experimental factors. Mean comparisons

were performed using Duncan Multiple

Range Test (DMRT) set at 0.05.


Experiment 1: Ryegrass

Results (Tables 1 to 4) showed that all

commercial formulations of clodinafop

propargyl had greater effects on reducing

the fresh (Table 1) and dry (Table 2)

weights of ryegrass when applied without

adjuvants compared with those of

pinoxaden. In contrast, the addition of the

adjuvants increased the foliar activity of

pinoxaden more than that of clodinafop

propargyl formulations (P < 0.05). This

indicated that adjuvant receptivity for

pinoxaden was higher than that for

clodinafop propargyl. The addition of Volk

and Citohef had the highest and the lowest

effects on performance of pinoxaden,

respectively. It is possible to rank the

tested adjuvants as Volk > Adigor >

Citogate > Citohef in their decreasing

ability to enhance the efficacy of

pinoxaden. Petroleum oils such as Volk

and methylated seed oils such as Adigor

probably disrupt and solubilize cuticular

waxes (Zabkiewicz, 2000) and


consequently, facilitate the penetration of

the active ingredient (McMullan & Chow,

1993). The benefits of using these oils (e.g.

Volk & Adigor) rather than surfactants

(e.g. Citogate & Citohef) in enhancing the

foliage activity of herbicides have been

well documented in other studies (Bunting

et al., 2004a; Ramsdale & Messersmith,

2002; Bunting et al., 2004b; Rashed-

Mohassel et al. 2010). Sharma and Singh

(2000) reported that an increase in the

penetration of the active ingredient through

softening or disrupting the cuticular waxes

is a more effective factor than decreasing

the surface tension of spray droplets in

improving the foliar activity of glyphosate

on Bidens frondosa and Panicum

maximum. Therefore, the foliar activity of

the pinoxaden might be increased due to

the ability of either Volk or Adigor to

soften or disrupt the cuticular waxes.

Unlike pinoxaden, the addition of the

adjuvants to clodinafop propargyl

formulations did not significantly affect

their performance. Nonetheless, Volk had

the highest influence on improving the

foliar activity of clodinafop propargyl

formulations. Citohef application led to an

insignificant antagonistic effect on the

foliar activity of clodinafop propargyl

formulations resulting in a decrease in

performance of all formulations of this

herbicide. The mortality of ryegrass plants

was improved with an increase in

concentration of pinoxaden especially

when applied with adjuvants (Table 4).

The mortality of ryegrass plants did not

change in none of clodinafop propargyl

formulations when applied with Adigor,

Citohef, and Volk. However, Citogate led

to a significant increase in survival of

ryegrass plants (Table 3).

Experiment 2: Little Seed Canarygrass

Results (Tables 5-8) indicated that the

foliar activity of herbicides was improved

with increasing the concentration of

pinoxaden. Pinoxaden at high

concentrations (> 50 g a.i ha-1) caused

complete weed control (Table 8) and

showed greater efficacy than all clodinafop

propargyl formulations when used without

adjuvants. The performance of pinoxaden

was enhanced significantly (P < 0.05)

when adjuvants were added. Adigor and

Volk had the highest effect while Citogate

and Citohef showed the lowest effect on

pinoxaden performance. The addition of

adjuvants to pinoxaden at 40 g a.i. ha-1 led

to complete littleseed canarygrass control

(Table 8). All adjuvants increased

performance of clodinafop propargyl

formulations against this weed. The

application of adjuvants did not have any

positive effect on formulations Behpik and

Karent. In case of Topik formulation,

however, Citogate and Citohef had the

highest, and Adigor and Volk had the

lowest effects on performance of this

herbicide. Therefore, these results

emphasize the dependency of adjuvant

performance on herbicide properties and

plant species as previous studies also stated

(Johnson et al., 2002; Rashed-Mohassel et

al., 2010). The data from this experiment

showed that the number of surviving

littleseed canarygrass plants increased

when the adjuvants were added to

clodinafop propargyl formulations (Table

7). However, all adjuvant-added

clodinafop propargyl formulations showed

Ability of Adjuvants in Enhancing the Performance

superior performance in reducing the fresh

and dry weight of little seed canarygrass

(Table 5 & 6). According to the EWRC

index, all clodinafop propargyl

formulations acted weaker than pinoxaden

either with (> 30 g a.i. L-1) or withou

40 g a.i. L-1) the adjuvants (Table 8). This

indicates that the adjuvants are likely to

improve the penetrability of the active

ingredient (Johnson et al., 2002) which

provides an opportunity to reduce

herbicide application dose (Zabkiewicz,

2000).

Experiment 3: Wild Oat

Increasing pinoxaden concentration up to

60 g a.i. ha-1 enhanced its weed control

efficacy (Table 12). This herbicide

controlled weeds completely at higher

does. All adjuvant enhanced the efficacy

of pinoxaden in decreasing the fresh

9) and dry (Table 10) weights of wild oat.

Volk was the most effective adjuvant as its

addition to pinoxaden at 30 g a.i. ha

complete control of wild oat, while higher

herbicide dose was needed for other

adjuvants to achieve complete weed

control. It was clearly indicated that

pinoxaden has a vigorous receptivity for

adjuvant which might be related to weaker

penetration of pinoxaden into wild oat leaf

when applied without adjuvant. This can

be a reason for why pinoxaden is being

sold with a particular adjuvant (Adigor).

However, the results from the present

experiment indicated that the addition of

Adigor had the lowest influence on

pinoxaden performance among adjuvants.

Generally, the adjuvants could be ranked

as Volk being the most effective adjuvant

followed by Citohef, Citogate,

bility of Adjuvants in Enhancing the Performance …

superior performance in reducing the fresh

and dry weight of little seed canarygrass

(Table 5 & 6). According to the EWRC

index, all clodinafop propargyl

formulations acted weaker than pinoxaden

) or without (>

) the adjuvants (Table 8). This

indicates that the adjuvants are likely to

improve the penetrability of the active

., 2002) which

provides an opportunity to reduce

herbicide application dose (Zabkiewicz,

Increasing pinoxaden concentration up to

enhanced its weed control

efficacy (Table 12). This herbicide

controlled weeds completely at higher

does. All adjuvant enhanced the efficacy

of pinoxaden in decreasing the fresh (Table

9) and dry (Table 10) weights of wild oat.

Volk was the most effective adjuvant as its

addition to pinoxaden at 30 g a.i. ha-1 led to

complete control of wild oat, while higher

herbicide dose was needed for other

adjuvants to achieve complete weed

control. It was clearly indicated that

pinoxaden has a vigorous receptivity for

adjuvant which might be related to weaker

penetration of pinoxaden into wild oat leaf

when applied without adjuvant. This can

be a reason for why pinoxaden is being

particular adjuvant (Adigor).

However, the results from the present

experiment indicated that the addition of

Adigor had the lowest influence on

pinoxaden performance among adjuvants.

could be ranked

being the most effective adjuvant

Citogate, and Adigor.

Based on the available literature (Singh &

Mack , 1993; Kocher & Kocur,

seems that the tested adjuvants led to more

cuticular penetration and stomata

infiltration and subsequently, allowed

better pinoxaden absorption and

translocation. The efficacy of clodinafop

propargyl formulations did not change

significantly by increase in their

concentration and all treatments resulted in

complete control of wild oat (Table 12).

Rashed-Mohassel et al

similar result that the Topik formulation of

clodinafop propargyl at 48 and 64 g a.i. ha1 showed no significant difference in wild

oat (Avena fatua L.) control ability. This

finding can be related to high sensitivity o

wild oat plant to clodinafop propargyl

and/or high efficacy of this herbicide in

controlling wild oat. Moreover, the

addition of the adjuvants did not have any

positive effect on efficacy of the three

formulations of clodinafop propargyl

against wild oat (Table 12).

Overall, our study showed that although

Citogate and Citohef chemical

characteristics and formulations are similar

(non-ionic surfactant

alkylarylpolyglycol ether) but they differ in

their performance. In experiments 1 and 2,

Citogate was more an effective adjuvant in

enhancing the efficacy of pinoxaden

against ryegrass and littleseed canarygrass,

while in experiment 3, Citohef acted better

in increasing the efficacy of pinoxaden

against wild oat. These results indicated

that the differences in leaf surface

micromorphology can affect the efficacy of

an adjuvant as previously shown in other

studies (Collins & Helling, 2002; Sanyal

… 69

Based on the available literature (Singh &

Kocher & Kocur, 1993), it

seems that the tested adjuvants led to more

cuticular penetration and stomata

bsequently, allowed

better pinoxaden absorption and

translocation. The efficacy of clodinafop

propargyl formulations did not change

significantly by increase in their

concentration and all treatments resulted in

complete control of wild oat (Table 12).

et al., (2009) reported

similar result that the Topik formulation of

clodinafop propargyl at 48 and 64 g a.i. ha-

showed no significant difference in wild

L.) control ability. This

finding can be related to high sensitivity of

wild oat plant to clodinafop propargyl

and/or high efficacy of this herbicide in

controlling wild oat. Moreover, the

addition of the adjuvants did not have any

positive effect on efficacy of the three

formulations of clodinafop propargyl

(Table 12).

Overall, our study showed that although

Citogate and Citohef chemical

characteristics and formulations are similar

ionic surfactants, 100%

alkylarylpolyglycol ether) but they differ in

their performance. In experiments 1 and 2,

was more an effective adjuvant in

enhancing the efficacy of pinoxaden

against ryegrass and littleseed canarygrass,

while in experiment 3, Citohef acted better

in increasing the efficacy of pinoxaden

against wild oat. These results indicated

rences in leaf surface

micromorphology can affect the efficacy of

an adjuvant as previously shown in other

studies (Collins & Helling, 2002; Sanyal et


al., 2006). In other words, the efficacy of an adjuvant also depends on species.

Table 1. Effects of pinoxaden and three commercial formulations of clodinafop propargyl applied with and

without adjuvants* on ryegrass fresh weight.

Herbicides Rate

g a.i. ha-1

No adjuvant Adigor Citogate Citohef Volk

Fresh weight (g)

Pinoxaden 30 2.22 a** 0.63 a 0.71 ab 1.19 a 0.29 bcde

Pinoxaden 40 2.19 a 0.34 cd 0.69 ab 0.46 cd 0.00 e

Pinoxaden 50 1.34 b 0.00 e 0.13 cd 0.42 cd 0.00 e

Pinoxaden 60 1.24 b 0.00 e 0.00 d 0.00 e 0.00 e

Pinoxaden 70 0.00 d 0.00 e 0.00 d 0.00 e 0.00 e

Clodinafop propargyl (Topik) 48 0.46 dc 0.52 ab 0.87 a 0.97 ab 0.55 bc

Clodinafop propargyl (Topik) 64 0.41 d 0.20 d 0.00 d 0.88 ab 0.59 bc

Clodinafop propargyl (Behpik) 48 0.81 bc 0.43 cb 0.40 bc 0.76 bc 0.59 b

Clodinafop propargyl (Behpik) 64 0.26 cd 0.29 d 0.23 cd 0.18 de 0.65 a

Clodinafop propargyl (Karent) 48 0.58 bdc 0.46 b 0.68 ab 0.41 cd 0.25 cde

Clodinafop propargyl (Karent) 64 0.62 bdc 0.21 d 0.28 cd 0.79 bc 0.16 ed

* All adjuvants were added at 0.2 % (v/v). ** Treatment means within a column followed by the same letter are not significantly different (P < 0.05) according to Duncan’s Multiple Range test.

Table 2. Effects of pinoxaden or three commercial formulations of clodinafop propargyl applied with and

without adjuvants* on ryegrass dry weight.

Herbicides Rate

g a.i. ha-1


Dry weight (g)

Pinoxaden 30 0.27 cb** 0.12 a 0.11 b 0.17 a 0.05 a

Pinoxaden 40 0.22 cd 0.03 d 0.09 a 0.06 de 0.00 c

Pinoxaden 50 0.16 b 0.00 e 0.02 cd 0.04 ef 0.00 c

Pinoxaden 60 0.02 cd 0.00 e 0.00 d 0.00 g 0.00 c

Pinoxaden 70 0.00 f 0.00 e 0.00 d 0.00 g 0.00 c

Clodinafop propargyl (Topik) 48 0.06 ef 0.08 bc 0.06 bc 0.14 bc 0.06 a

Clodinafop propargyl (Topik) 64 0.05 ef 0.05 bc 0.00 d 0.12 ab 0.04 b

Clodinafop propargyl (Behpik) 48 0.08 de 0.04 c 0.06 bc 0.10 ab 0.04 a

Clodinafop propargyl (Behpik) 64 0.05 ef 0.09 bc 0.03 cd 0.02 gf 0.01 a

Clodinafop propargyl (Karent) 48 0.07 ef 0.03 c 0.07 b 0.05 c 0.05 b

Clodinafop propargyl (Karent) 64 0.90 a 0.03 bc 0.04 cd 0.11 d 0.04 b

* All adjuvant were added at 0.2 % (v/v). ** Treatment means within a column followed by the same letter are not significantly different (P < 0.05) according to Duncan’s Multiple Range test.


Table 3. The number of the survived plants of ryegrass after spraying with pinoxaden and three commercial

formulations of clodinafop propargyl applied with and without adjuvants*.

Herbicides Rate

g a.i. ha-1


Survived plants (plant pot-1)

Pinoxaden 30 3.75 a** 2.00 a 2.00 a 2.50 a 1.00 b

Pinoxaden 40 3.25 a 1.00 b 1.50 ab 1.00 c 0.00 c

Pinoxaden 50 2.00 b 0.00 c 1.00 c 1.00 c 0.00 c

Pinoxaden 60 1.75 bc 0.00 c 0.00 d 0.00 d 0.00 c

Pinoxaden 70 0.00 d 0.00 c 0.00 d 0.00 d 0.00 c

Clodinafop propargyl (Topik) 48 1.00 c 1.00 b 1.50 abc 1.00 c 1.00 b

Clodinafop propargyl (Topik) 64 1.00 c 1.00 b 0.00 d 1.00 c 1.00 b

Clodinafop propargyl (Behpik) 48 1.25 bc 1.00 b 1.50 abc 1.00 c 1.00 b

Clodinafop propargyl (Behpik) 64 1.00 c 1.00 b 1.00 c 1.00 c 1.00 b

Clodinafop propargyl (Karent) 48 1.00 c 1.00 b 1.25 c 1.00 c 1.00 b

Clodinafop propargyl (Karent) 64 1.50 bc 1.00 b 1.00 c 1.00 c 1.00 b


Table 4. Percent control of ryegrass by pinoxaden and three commercial formulations of clodinafop propargyl

applied with and without adjuvant*.

Herbicides Rate

g a.i. ha-1


Control (%)

Pinoxaden 30 22.50 d** 83.75 d 76.25 cd 55.00 d 90.00 b

Pinoxaden 40 32.50 d 92.50 b 92.50 ab 91.25 a 100 a

Pinoxaden 50 71.25 c 100 a 92.50 ab 91.50 a 100 a

Pinoxaden 60 77.50 c 100 a 100 a 100 a 100 a

Pinoxaden 70 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Topik) 48 81.25 bc 85.00 c 77.50 cd 67.50 c 82.50 c

Clodinafop propargyl (Topik) 64 95.50 ab 90.00 bc 100 a 76.25 bc 88.75 bc

Clodinafop propargyl (Behpik) 48 68.00 c 70.00 e 73.75 d 68.75 c 75.00 d

Clodinafop propargyl (Behpik) 64 93.75 ab 91.25 bc 93.75 ab 93.75 a 86.25 bc

Clodinafop propargyl (Karent) 48 76.00 cd 87.50 cd 82.50 bcd 75.50 bc 87.50 bc

Clodinafop propargyl (Karent) 64 88.00 ab 100 a 90.00 abc 87.50 ab 92.50 b




without adjuvants* on littleseed canarygrass fresh weight.

Herbicides Rate

g a.i. ha-1


Fresh weight (g)

Pinoxaden 30 3.04 a** 0.00 d 1.17 a 0.46 a 0.00 d

Pinoxaden 40 1.82 b 0.00 d 0.00 b 0.00 c 0.00 d

Pinoxaden 50 0.00 e 0.00 d 0.00 b 0.00 c 0.00 d

Pinoxaden 60 0.00 e 0.00 d 0.00 b 0.00 c 0.00 d

Pinoxaden 70 0.00 e 0.00 d 0.00 b 0.00 c 0.00 d

Clodinafop propargyl (Topik) 48 0.12 cd 0.18 a 0.17 b 0.11 b 0.15 a

Clodinafop propargyl (Topik) 64 0.09 d 0.23 a 0.11 b 0.11 b 0.15 a

Clodinafop propargyl (Behpik) 48 0.13 cd 0.10 b 0.16 b 0.11 b 0.14 ab

Clodinafop propargyl (Behpik) 64 0.12 cd 0.08 bc 0.09 b 0.07 b 0.14 ab

Clodinafop propargyl (Karent) 48 0.14 cd 0.10 b 0.15 b 0.07 b 0.09 c

Clodinafop propargyl (Karent) 64 0.13 cd 0.05 cd 0.09 b 0.06 b 0.10 bc



without adjuvant* on littleseed canarygrass dry weight.

Herbicides Rate

G a.i. ha-1


Dry weight (g)

Pinoxaden 30 0.40 a** 0.00 e 0.24 a 0.60 a 0.00 d

Pinoxaden 40 0.24 b 0.00 e 0.00 e 0.00 c 0.00 d

Pinoxaden 50 0.00 d 0.00 e 0.00 e 0.00 c 0.00 d

Pinoxaden 60 0.00 d 0.00 e 0.00 e 0.00 c 0.00 d

Pinoxaden 70 0.00 d 0.00 e 0.00 e 0.00 c 0.00 d

Clodinafop propargyl (Topik) 48 0.04 c 0.05 b 0.05 c 0.04 b 0.06 a

Clodinafop propargyl (Topik) 64 0.04 c 0.10 a 0.05 cd 0.05 b 0.05 ab

Clodinafop propargyl (Behpik) 48 0.05 c 0.03 d 0.05 c 0.04 b 0.05 ab

Clodinafop propargyl (Behpik) 64 0.04 c 0.05 bc 0.03 d 0.03 b 0.05 ab

Clodinafop propargyl (Karent) 48 0.05 c 0.04 cd 0.05 c 0.02 bc 0.04 b

Clodinafop propargyl (Karent) 64 0.05 c 0.00 e 0.03 cd 0.02 bc 0.03 c



Table 7. The number of survived plants of littleseed canarygrass after spraying with pinoxaden and three

commercial formulations of clodinafop propargyl applied with and without adjuvants*.

Herbicides Rate

g a.i. ha-1


Survived plants (plant pot-1)

Pinoxaden 30 4.75 a** 0.00 c 3.50 a 1.25 bc 0.00 b

Pinoxaden 40 4.50 a 0.00 c 0.00 c 0.00 c 0.00 b

Pinoxaden 50 0.00 e 0.00 c 0.00 c 0.00 c 0.00 b

Pinoxaden 60 0.00 e 0.00 c 0.00 c 0.00 c 0.00 b

Pinoxaden 70 0.00 e 0.00 c 0.00 c 0.00 c 0.00 b

Clodinafop propargyl (Topik) 48 1.75 cd 1.50 b 2.25 ab 2.70 a 2.75 a

Clodinafop propargyl (Topik) 64 0.75 e 1.00 bc 1.25 bc 0.75 bc 2.00 a

Clodinafop propargyl (Behpik) 48 1.50 cd 2.25 a 3.00 a 1.75 ab 2.00 a

Clodinafop propargyl (Behpik) 64 1.00 cd 1.00 bc 1.50 b 1.75 ab 2.25 a

Clodinafop propargyl (Karent) 48 1.00 e 1.75 b 2.50 ab 2.00 ab 2.50 a

Clodinafop propargyl (Karent) 64 1.25 e 1.50 b 1.50 b 1.75 ab 2.25 a


Table 8. Percent control of littleseed canarygrass by pinoxaden and three commercial formulations of clodinafop

propargyl applied with and without adjuvants*.

Herbicides Rate

g a.i. ha-1


Control (%)

Pinoxaden 30 22.50 c** 100 a 47.50 d 83.75 bc 100 a

Pinoxaden 40 23.75 c 100 a 100 a 100 a 100 a

Pinoxaden 50 100 a 100 a 100 a 100 a 100 a

Pinoxaden 60 100 a 100 a 100 a 100 a 100 a

Pinoxaden 70 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Topik) 48 61.25 b 81.25 b 66.25 bcd 60.00 d 60.00 b

Clodinafop propargyl (Topik) 64 87.50 a 86.25 ab 83.75 ab 91.25 ab 72.50 b

Clodinafop propargyl (Behpik) 48 55.50 b 58.75 c 60.00 cd 73.75 cd 71.25 b

Clodinafop propargyl (Behpik) 64 55.50 b 85.00 ab 78.75 bc 78.75 bc 71.25 b

Clodinafop propargyl (Karent) 48 86.25 a 72.50 b 67.50 bc 73.75 cd 60.00 b

Clodinafop propargyl (Karent) 64 70.00 b 76.25 b 78.75 bc 77.50 bc 70.00 b




without adjuvants* on wild oat fresh weight.

Herbicides Rate

g a.i. ha-1

No

adjuvant Adigor Citogate Citohef Volk

Fresh weight (g)

Pinoxaden 30 49.12 a** 9.05 a 3.26 a 0.50 a 0.00 a

Pinoxaden 40 26.54 b 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 50 4.85 c 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 60 4.29 c 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 70 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a

Clodinafop propargyl (Topik) 48 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a


Clodinafop propargyl (Behpik) 48 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a


Clodinafop propargyl (Karent) 48 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a




without adjuvants* on wild oat dry weight.

Herbicides Rate

g a.i. ha-1


Dry weight (g)

Pinoxaden 30 6.52 a** 0.99 a 0.31 a 0.03 a 0.00 a

Pinoxaden 40 3.23 b 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 50 0.60 c 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 60 0.32 cd 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 70 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a









Table 11. The number of survived plants of wild oat after spraying with pinoxaden and three commercial

formulations of clodinafop propargyl applied with and without adjuvants*.

Herbicides Rate

g a.i. ha-1


wild oat (plant pot-1)

Pinoxaden 30 5.00 a** 1.00 a 0.75 a 0.25 a 0.00 a

Pinoxaden 40 2.00 b 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 50 0.50 c 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 60 0.50 c 0.00 b 0.00 b 0.00 a 0.00 a

Pinoxaden 70 0.00 d 0.00 b 0.00 b 0.00 a 0.00 a








Table 12. Percent control of wild oat by pinoxaden and three commercial formulations of clodinafop propargyl

applied with and without adjuvants*.

Herbicides Rate

g a.i. ha-1


Control (%)

Pinoxaden 30 15.00 c** 89.50 b 78.25 b 95.50 a 100 a

Pinoxaden 40 56.25 b 100 a 100 a 100 a 100 a

Pinoxaden 50 93.25 a 100 a 100 a 100 a 100 a

Pinoxaden 60 92.75 a 100 a 100 a 100 a 100 a

Pinoxaden 70 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Topik) 48 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Topik) 64 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Behpik) 48 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Behpik) 64 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Karent) 48 100 a 100 a 100 a 100 a 100 a

Clodinafop propargyl (Karent) 64 100 a 100 a 100 a 100 a 100 a


Acknowledgements

The financial support from the Department

of Weed Research, the Iranian Plant

Protection Research Institute, Tehran is

gratefully acknowledged.

REFERENCES

Baghestani, M. A., Zand, E., Soufizadeh, S., Jamali,

M. and Maighany, F. 2007. Evaluation of

sulfosulfuron for broadleaved and grass weed

control in wheat (Triticum aestivum) in Iran.

Crop Protection 26: 1385-1389.

76

Baghestani, M. A., Zand, E., Soufizadeh

Beheshtian, M., Haghighi, A., Barjasteh, A.,

Ghanbarani Birgani, D. and Deihimf

2008. Study on the efficacy of weed control in

wheat (Triticum aestivum) with tank mixtures

of grass herbicides with broadleaved

herbicides. Crop Protection. 27

Bunting, J. A., Spragueand, C. L. and Riechers, D.

E. 2004a. Proper adjuvant

foramsulfuron activity. Crop Pr

361-366.


E. 2004b. Absorption and activity of

foramsulfuron in giant foxtail (

and woolly cupgrass (Eriochloa villosa

various adjuvants. Weed Science

Collins, R. T. and Helling, C. S. 2002. Surfactant

enhanced control of two Erythroxylum

by glyphosate. Weed Technology

859.

Devine, M. D. and Shimabukuro,

Resistance to acetyl coenzyme A carboxylase

inhibiting herbicides. In: Powles S.B. and

Holtum J.A.M., eds. Herbicide Resistance in

Plants Biology and Biochemistry. Boca Raton,

FL: Lewis. pp. 141-169.

Green, J. M. and Foy, C. L. 2000. Adjuvants: test

design, interpretation, and presentation of

results. Weed Technology 14: 819

Johnson, H. E., Hazen, J. L. and Penner, D.

Citric ester surfactants as adjuvants with

herbicides. Weed Technology 16

Kocher, H. and Kocur, J. 1993

wetting agents on the foliar uptake and

herbicidal activity of glufosinate.

Science 37: 155-158.

McMullan, P. M. and Chow, P. N. P.

Efficacious adjuvants for fluazifop or

sethoxydim in flax and canola.

Protection 12: 544-548.

Ramsdale, B. K. and Messersmith, C.

Adjuvant and herbicide concentration in spray

.

Mousavinik et al. (2009)/ Iranian Journal of Weed Science 5 (2)

Soufizadeh, S.,

Beheshtian, M., Haghighi, A., Barjasteh, A.,

Ghanbarani Birgani, D. and Deihimfard, R.

2008. Study on the efficacy of weed control in

) with tank mixtures

of grass herbicides with broadleaved

27: 104-111.


selection for

Crop Protection 23:


2004b. Absorption and activity of

foramsulfuron in giant foxtail (Setaria faberi)

Eriochloa villosa) with

Weed Science 52: 513-517.

, C. S. 2002. Surfactant

Erythroxylum species

Weed Technology 16: 851–

Devine, M. D. and Shimabukuro, R. H. 1994.

Resistance to acetyl coenzyme A carboxylase

owles S.B. and

Holtum J.A.M., eds. Herbicide Resistance in

Plants Biology and Biochemistry. Boca Raton,

2000. Adjuvants: test

design, interpretation, and presentation of

819-825.

Johnson, H. E., Hazen, J. L. and Penner, D. 2002.

Citric ester surfactants as adjuvants with

16: 867-872.

1993. Influence of

wetting agents on the foliar uptake and

fosinate. Pesticide

McMullan, P. M. and Chow, P. N. P. 1993.

Efficacious adjuvants for fluazifop or

sethoxydim in flax and canola. Crop

Ramsdale, B. K. and Messersmith, C. 2002.

Adjuvant and herbicide concentration in spray

droplets influence phytotoxicity.

Technology 16: 631-637.

Rashed-Mohassel, M. H., Aliverdi, A. and

Ghorbani, R. 2009. Effects of a magnetic field

and adjuvant in the efficacy of cycloxydim and

clodinafop propargyl on the control of wild oat

(Avena fatua). Weed Biology and Management

9: 300-306.

Rashed-Mohassel, M. H., Aliverdi, A., Hamami, H.

and Zand, E. 2010

performance of diclofop

and clodinafop propargyl on littles

canarygrass (Phalaris minor

(Avena ludoviciana) control with adjuvants.

Weed Biology and Managemen

Sandral, G. H., Dear, B. S., Pratley, J. E. and Cullis,

B. R. 1997. Herbicide dose response rate curve

in subterranean clover de

bioassay. Australian Journal of Experimental

Agriculture 37: 67-74.

Sanyal, D., Bhowmik, P. C. and Reddy, K. N. 2006

Influence of leaf surface micro morphology,

wax content, and surfactant on primisulfuron

droplet spread on barnyardgrass (

crus-galli) and green foxtail (

Weed Science 54: 627-633.

SAS Institute Inc. 2000.

windows, release 8.0. Statistical Analysis

Systems Institute, Carry, NC.

Sharma, S. D. and Singh, M. 2000.

foliar activity of glyphosate on

frondosa and Panicum maximum

adjuvant types. Weed Research

Singh, M. and Mack, R. E.

organosilicone-based adjuvants on herbicide

efficacy. Pesticide Science

Zabkiewicz, J. A. 2000. Adjuvants and herbicidal

efficacy present status and future prospects.

Weed Research 40: 139-

Zolinger, R. K. 2000. Extension perspective on

grower confusion in adjuvant selection.

Technology 14: 814-818

(2009)/ Iranian Journal of Weed Science 5 (2)

droplets influence phytotoxicity. Weed

637.

Mohassel, M. H., Aliverdi, A. and

. Effects of a magnetic field

and adjuvant in the efficacy of cycloxydim and

propargyl on the control of wild oat

Weed Biology and Management

Mohassel, M. H., Aliverdi, A., Hamami, H.

and Zand, E. 2010. Optimizing the

performance of diclofop-methyl, cycloxydim,

and clodinafop propargyl on littleseed

Phalaris minor) and wild oat

) control with adjuvants.

Weed Biology and Managemen 10: 57-63.

Sandral, G. H., Dear, B. S., Pratley, J. E. and Cullis,

. Herbicide dose response rate curve

in subterranean clover determined by a

Australian Journal of Experimental

Sanyal, D., Bhowmik, P. C. and Reddy, K. N. 2006.

Influence of leaf surface micro morphology,

wax content, and surfactant on primisulfuron

droplet spread on barnyardgrass (Echinochloa

) and green foxtail (Setaria viridis).

633.

The SAS system for

windows, release 8.0. Statistical Analysis

Systems Institute, Carry, NC.

Sharma, S. D. and Singh, M. 2000. Optimizing

foliar activity of glyphosate on Bidens

Panicum maximum with different

Weed Research 40: 523-533.

Singh, M. and Mack, R. E. 1993. Effect of

based adjuvants on herbicide

Pesticide Science 38: 219-225.

. Adjuvants and herbicidal

efficacy present status and future prospects.

-149.

Extension perspective on

grower confusion in adjuvant selection. Weed

818


چكيده

هاي مناسب به منظور شناسايي مويان. هاي اصلي تحقيقات در زمينه مويان محسوب مي شودكش ها از اواويتها در افزايش كاركرد علفتوانايي مويان

قناريبراي علف كش هاي پينوكسادن و كلودينافوپ پروپارژيل براي كنترل علف هاي هرز علف

(Phalaris minor Retz.) يوالف وحشي ،(Avena fatua L.) و چچم(Lolium temulentum L.) سه آزمايش گلخانه اي جداگانه ،

در تمامي آزمايش ها تيمارها شامل پنج غلظت پينوكسادن و دو غلظت از هر يك از سه فرموالسيون تجاري كلودينافوپ پروپارژيل . صورت پذيرفت

اصل از آزمايش نشان داد كه با افزايش نتايج ح. يعني تاپيك، بهپيك و كارنت، با و بدون كاربرد مويان هاي آديگور، سيتوگيت، سيتوهف و ولك بودند

. غلظت علف كش، كارايي هر دو علف كش در كنترل علف هاي هرز، به جز علف كش كلودينافوپ پروپارژيل بر روي يوالف وحشي، افزايش پيدا كرد

ري داشت كه در تاييد اين مطلب است كاربرد ولك بيشترين تاثير مثبت را روي كارايي علف كش پينوكسادن در كنترل علف هاي هرز چچم و علف قنا

همچنين، كاربرد ولك و آديگور به . كه مويان هاي ولك و آديگور كوتيكول مومي برگ را در خود حل كرده و بدين سان جذب آنها افزايش مي يابد

مجموع، تمايل علف كش پينوكسادن در. ترتيب بيشترين و كمترين تاثير را بر روي كارايي علف كش هاي پينوكسادن در كنترل يوالف وحشي داشت

همچنين، مويان سيتوگيت در مقايسه با سيتوهف تاثير بيشتري در افزايش كارايي علف . براي جذب مويان بيشتز از علف كش كلودينافوپ پروپارژيل بود

كسادن در برابر علف هرز يوالف وحشي كش پينوكسادن در برابر علف هاي هرز چچم و علف قناري داشت درحاليكه سيتوهف در افزايش كارايي پينو

. موثرتر بود

. ادن، چچم، يوالف وحشيس، كلودينافوپ پروپارژيل، علف قناري، پينوكمواد افزودني :كليديكلمات


Effects of Row Spacing and Weed Control Duration on Yield, Yield Components and Oil Content of Canola

∗M. Rajabian1Departement of Agronomy, Faculty of Agriculture, Gilan University, Gilan, Iran,

(Received 27 November 2010; returned 12 March 2011; accepted 25 May 2011)

ABSTRACT

In order to study the effects o

components and oil content of canola, a factorial

complete block design with 3 replications. The factors comprised row spacing at 2 levels (25

and 35 centimeter) and weed control 4, 8 leaf stages and formation of flower buds. Weeds

were permitted to grow by the cr

treatments as control, including weedy and weed free were also selected. Evaluated traits were

number of pods.plant-1, number of grains.pod

and oil yield. Results showed that different row spacing had significant effect on all traits

except oil content. Increase in row spacing was significantly accompanied by increase in pod

number.plant-1 and 1000-grain weight. Other traits were significantly decreased with

increasing row spacing. In addition, increase in weed control duration resulted in significant

increase in all traits except oil content. The interaction of row spacing

was also significant for all traits except 1000

results, the highest values of grain and oil yield were related to 25 centimeter row spacing on

total weed free check and the lowest amounts of these traits were obtained from 35 centimeter

row spacing on weedy check treatment.

Key words: row spacing, weed control duration, grain yield, oil content, canola

Corresponding author: E-mail: [email protected]


Effects of Row Spacing and Weed Control Duration on Yield, Yield Components and Oil Content of Canola

M. Rajabian1, J. Asghari1, S. M. R. Ehteshami1, M. Rabiee

Departement of Agronomy, Faculty of Agriculture, Gilan University, Gilan, Iran, 2 Rice Resea

Rasht, Iran

Received 27 November 2010; returned 12 March 2011; accepted 25 May 2011)

In order to study the effects of row spacing and weed control duration

components and oil content of canola, a factorial experiment was conducted using randomized



were permitted to grow by the crop after the above mentioned growth stages. Two check


, number of grains.pod-1, 1000-grain weight, grain yield, oil content

Results showed that different row spacing had significant effect on all traits


grain weight. Other traits were significantly decreased with


increase in all traits except oil content. The interaction of row spacing × weed control duration

was also significant for all traits except 1000-grain weight and oil content. Based on the



row spacing on weedy check treatment.

ow spacing, weed control duration, grain yield, oil content, canola


Effects of Row Spacing and Weed Control Duration on Yield, Yield

, M. Rabiee2

Rice Research Institute,

f row spacing and weed control duration on yield, yield

experiment was conducted using randomized



op after the above mentioned growth stages. Two check


grain weight, grain yield, oil content

Results showed that different row spacing had significant effect on all traits


grain weight. Other traits were significantly decreased with


weed control duration

nd oil content. Based on the



ow spacing, weed control duration, grain yield, oil content, canola

80 Radjabian et al. (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Canola (Brassica napus L.) is the third

largest oilseed crop production, after

soybean and palm producing as much as

14.7% of total vegetable edible oil in the

world (Yasari et al., 2008).

It is well known that weeds interference

with crop plants causes serious impacts

either in the competition for light, water,

nutrients and space or in the allelopathy.

Canola as a slow growing crop is

particularly exposed to severe competition

by weeds. Faster growth of weeds is

disadvantageous for light and hence

photosynthesis needed for rapeseed plants.

Through this light deprivation, a less

energy is available to crop plant for

metabolic production and hence growth,

yield and its quality of rapeseed plant will

be reduced. In addition, weeds with

branched, vigorous root systems inhibit the

development of canola plant through

severe nutrition deprivation (Roshdy et al.,

2008). Duration of weed interference is

one of the effective factors on weed-crop

competition. Weed interference with crops

is not similar in various growth and

development stages; therefore, weed-crop

competition capability is different in their

life cycle (Tollenaar et al., 1994).

Reduction of weed interference and

increase in control durations causes

increase in yield and yield components.

Aghaalikhani and Yaghoobi, (2008)

reported that yield of canola increased with

increasing the weed control duration.

(Hamzei et al., 2007) found that grain and

oil yield of canola were increased

significantly by increasing length of weed-

free period. Roshdy et al., 2008 also

expressed that yield and yield components

of canola were increased in weed control

treatments, but oil content was not

affected.

Row spacing or density is one of the most

important management factors indicating

amount of radiation intercepted per plant

(Fernando et al., 2002). Adjusting row

spacing is an important tool to optimize

crop growth and the time required for

canopy closure, along with maximum

biomass and grain yield (Ball et al., 2000;

Turgut et al., 2005; Svecnjak et al., 2006;

Haddadchi & Gerivani, 2009). Some

investigations concluded that narrow row

spacing resulted in higher yield than

boarder rows. Plants growing in too wide

rows may not efficiently utilize the natural

resources such as light, water and

nutrients, whereas growing in too narrow

rows may result in severe inter and intra-

row spacing competition (Ali et al., 1999).

Therefore, it is of crucially important to

manipulate the row spacing to increase

plant productivity (Yazdifar & Ramea,

2009). Yazdifar & Ramea, 2009 reported

that the highest grain yield of canola was

obtained at 12 cm row spacing, followed

by 7.4% reduction in grain yield as row

spacing increased to 24 cm. Ozer, 2003

also expressed that grain yield was

significantly affected by spacing within

rows, and canola yields were higher at the

narrow (15 cm) row spacing compared to

the middle (30 cm) and broader (45 cm)

spacings.

The objective of this study was to evaluate

the effects of row spacing and weed

control duration on yield, yield

Effects of Row Spacing and Weed Control Duration … 81

components and oil percent of canola

(Brassica napus L.).

MATERIALS AND MIETHODS

The experiment was conducted in paddy

fields of Rasht Rice Researches Institute

(51o 3' E longitude, 37o 16' N latitude and

an altitude of -7 m below sea level) during

2008-2009. The total annual precipitation

in the studied region is 1039 millimeters in

the growing season; soil texture was silty

clay loam with pH of 6.7 with

approximately 1.63% organic matter. The

experimental design was a factorial

randomized complete block with 3

replications. The factors comprised row

spacing at 2 levels (25 and 35 cm) and

weed control duration in 7 levels

(including hand weeding until the end of

crop emergence (VC) along with 2, 4, 8 leaf

stages (represented as V2, V4, V8,

respectively) and formation of flower buds

(FB)). Weeds were permitted to grow by

the crop after the above mentioned growth

stages. Two check treatments including

weedy and weed free were also selected. In

mid-September, the land was plowed with

moldboard plow. According to soil and

water recommendations by the Rice

Research Institute, basic fertilizers

including 100 kg.ha-1 urea, 150 kg.ha-1

ammonium phosphate and 150 kg.ha-1

potassium sulphate were added to the soil

simultaneously during plowing. The field

was subsequently flattened by rotary.

Experimental units were created in 2.5×3.5

m dimensions and 0.5 m away from the

adjacent experimental units. The blocks

were also 2 meters apart from each other.

Considering the climate conditions of

Rasht and likelihood floodings due to

meteoric precipitations, some drainage

channels were devised between the blocks

and experimental units. Plant density for

the 25 and 35 row spacing was 80 and 57

plants.m-2 and number of planting rows

were 7 and 10 rows for desired row

spacing’s respectively. The plant spacing

on rows was also 5 cm. Seeds were planted

in the mid-November 2008 in rows with

approximately 1-2 cm deep. The selected

canola cultivar was Hyola 401. Topdress

urea fertilizer was used as much as 100

kg.ha-1 during two stages, exiting from the

rosette stage (before stem elongation) and

squaring stage (before flowering).

Metaldehyde was also used particularly in

the early stages of rapeseed growth in

order to control the existing snails in the

farm. Irrigation is not required due to

adequacy of atmospheric precipitations

during canola growth stages. Treatments

were hand-harvested when 30-40% of the

seeds changed their color from green to

brown (late May in 25 row spacing and

early June in 35). Seed moisture was about

25% at harvest. Following the harvest,

plants were remained on the field for 2

days to be dried under sunlight. Seed

moisture at this time was about 12%.

Subsequently, threshing was done and

straws were separated from the seeds. To

determine the yield components (including

number of pods.plant-1 and number of

grains.pod-1) 10 plants were selected

randomly from each treatment and the

traits were measured. Grain yield was

determined from 5 m-2 of each plot after

removing marginal effect. Grain weight


was determined by grain counter device. In

this way/manner, 1000 grains were

selected from each yield sample and

weighted. Seed oil content was also

determined with the soxhlet apparatus.

SAS software v.9 (PROC GLM) was used

to analyze the data and mean comparison

was determined using the Tukey's multiple

range tests (at 1 and 5% levels of

probability).


Number of Pods.Plant-1

Results (Table 1) showed that the effect of

row spacing and duration of weed control

on pods number.plant-1 were significant

(P<0.01, Table 1). In addition, row spacing

and weed control duration had an

interaction effect on number of pods.plant-

1. Weed control duration influenced

maximum number of pods.plant-1 with the

most in the 25 row spacing treatment. In

other words, increase in row spacing and

increase in weed control duration increased

number of pods.plant-1. The highest and

lowest number of pods.plant-1 were related

to the total weed free check in 35 cm row

spacing (212.20 pods) and total weedy

check in 25 cm row spacing (73 pods),

respectively (Table 3).

Increase in row spacing significantly

increased the number of pods.plant-1,

which shows that this trait, in 25 cm row

spacing, was 15.08% lower than 35 cm

row spacing (Table 2). This might have

been the result of decline in light

interception by plant canopy in narrower

row spacing. Therefore, initiation of

constituent buds on secondary branches

declined. The decrease in the number of

secondary branches is the main cause of

decline in pods number.plant-1.

Furthermore, the diminishing carbohydrate

supply with exceeding competition among

the plants at the flowering time is another

reason (Eilkaee & Emam, 2003). This

result was consistent with those of

(Majnon Hosseini et al., 2006 & Ozer,

2003).

In both row spacing, number of pods.plant-

1 in control treatments indicated an uptrend

with increase in duration of weed-free and

reached its highest value in weed-free

check. The lowest number of pods.plant-1

was also related to weedy check in both

row spacing (Table 3). The average of

pods number.plant-1 in weed-free check in

comparison with weedy check indicated an

increase of 143.9% (Table 2). The reason

for decline in the number of pods.plant-1 is

increase in the duration of weed

interference which can be attributed to the

presence of weeds competing with

agricultural crops resulting in the diminish

of canola competition ability for receiving

light and nutrients as well as allocation of

less generated materials to the fertile

organs. In order to maintain the

equilibrium between generated materials of

the source and amount of consumed

materials in the reservoir, some of the

flowers shed (Safahani Langerodi et al.,

2008) and decreasing number of flowers

ultimately led to a decline in the number of

pods in the weedy check treatment. This

result was consistent with the results of the

research done by (Khoshnam, 2007 &

Keramati et al., 2008).

Number of Grains.Pod-1




on number of grains.pod-1 were significant

(P<0.01). In addition, row spacing and

weed control duration had an interaction

effect on number of grains.pod-1. Weed

control duration influenced maximum

number of grains.pod-1, mostly in the 25

row spacing treatment. In other words,

decrease in row spacing and increase in

weed control duration increased number of

grains.pod-1. The highest and lowest

number of grains.pod-1 were related to the

total weed free check in 25 cm row spacing

(29.32 seeds) and total weedy check in 35

cm row spacing (17.82 seeds), respectively

(Table 3).


decreased the number of grains.pod-1;

therefore this trait in 25 cm row spacing

was 12.648% higher than 35 cm row

spacing (Table 2). This phenomenon can

be justified as follow; as the row spacing

decreases (plant density increases), the

plant competition for absorbing

environmental resources exceeds resulting

in decrease in the production of

photosynthetic materials and its transfer to

grains (Leach et al., 1999; Salehi, 2004).

Consequently, the existing grains reduce in

size but increase in number. These results

were consistent with the results obtained

by (Rahman et al., 2009) & Ozoni Davaji,

2006) who believed that the increase in

plant density up to an optimal level would

result in the enhancement of number of

grains. On the contrary, obtained results

from this experiment contradicted the

results of (Abadian et al., 2008 & Eilkaee

& Emam, 2003) which concluded that row

spacing does not significantly affect

number of grains in the pods. In their

opinion, narrow row imposes its impact via

reduction of number of pods, and as a

result, there is no considerable decline in

the number of grains in the pods.

In both row spacings, number of

grains.pod-1 in control treatments showed

an uptrend with increase in duration of

weed-free and reached its highest value in

weed-free check. The lowest number of

grains.pod-1 was also related to weedy

check in both row spacings (Table 3). The

average of grains number.pod-1 in weed-

free check was 47.71% higher than weedy

check (Table 2). Reduction in grain

number.pod-1 in weedy check treatment

can be attributed to the diminishing

absorption of generated materials by the

agricultural crop and consequently draping

and elimination of the grains (Leach et al.,

1999). This result was consistent with the

results reported by (Khoshnam, 2007 &

Keramati et al., 2008).

1000-Grain Weight

Results of the current experiment (Table 1)

indicated that the effect of row spacing and

duration of weed control on 1000-grain

weight were significant (P<0.01). The

Results also showed no significant

response of 1000-grain weight with

interaction between these factors. The

highest and lowest 1000-grains weight

were related to the total weed free check in

35 cm row spacing (4.56 g) and the total

weedy check in 25 cm row spacing (3.1 g),

respectively (Table 3).


increased the 1000-grain weight, so that


this trait in 35 cm row spacing was 3.67%

higher than 25 cm row spacing (Table 2).

Reduction of grain weight in narrower row

spacing can be attributed to the formation

of smaller grains because of more limited

access to environmental resources

particularly light due to higher competition

among plants; declining production of

photosynthetic materials and finally,

transfer of less photosynthetic materials to

the grains especially at the time of grain

filling (Salehi, 2004; Abdolrahmani, 2003).

This result was consistent with the results

obtained by (Shekari & Javanshir, 2000;

Abdolrahmani, 2003 & Sedghi et al.,

2008), while contradicted with the results

of (Abadian et al., 2008 & Eilkaee &

Emam, 2003). The latter researchers

believed that different row spacing (plant

density) have no significant effects on

1000-grain weight. Their reason was that

grains act as strong physiological

reservoirs and rarely respond to the

treatments like row spacing (plant density).

In both row spacing, 1000-grain weight in

control treatments showed an uptrend with

increase in duration of weed-free and


check. The lowest 1000-grain weight also

related to weedy check in both row spacing

(Table 3). The average of 1000-grain

weight in weed-free check in comparison

with weedy check indicated an increase up

to 43% (Table 2). The reason for declining

1000 grain weight due to increase in the

duration of weed interference can be

explained as follows: in the case of weed

competition the amount of produced

photosynthetic materials diminished due to

the restricted availability of environmental

resources specifically sunlight which

reduces 1000-grain weight (Safahani

Langerodi et al., 2008; Eftekhari et al.,

2005). Similar results were also reported

by (Eftekhari et al., 2005 & Keramati et

al., 2008).

Grain Yield

Results (Table 1) indicated that the effect

of row spacing and duration of weed

control on grain yield were significant

(P<0.01). In addition, row spacing and

weed control duration had an interaction

effect on grain yield. Weed control

duration influenced maximum grain yield

the most in the 25 row spacing treatment.

In other words, decrease in row spacing

and increase in weed control duration

increased grain yield. The highest and

lowest amounts of grain yield were related

to the total weed free check in 25 cm row

spacing (4432.27 kg.ha-1) and the total

weedy check in 35 cm row spacing

(1940.33 kg.ha-1), respectively (Table 3).


decreased grain yield in manner that this

trait in 25 cm row spacing was 19.29%

higher than 35 cm row spacing (Table 2).

The reason can be postulated in a way

which grain yield is a function of some

parameters including; the number of

pods.plant-1, number of grains.pod-1 and

1000-grain weight. Although the decrease

in row spacing decreased the yield of

individual plant via reduction of pods

number as well as the 1000-grain weight

due to exceeded competition among plants

for utilizing environmental resources. On

the other hand, the increase in the total

number of plants compensated the weaker

yield of single plants. Accordingly, the


overall yield was enhanced per surface

area (Salehi, 2004). This result was

consistent with the results observed by

(Ozer, 2003 & Yazdifar et al., 2007).

In both row spacing, grain yield in control

treatments showed an uptrend with

increase in duration of weed-free and

reached its highest value in the weed-free

check. The lowest grain yield also related

to weedy check in both row spacings

(Table 3). The average of grain yield in

weed-free check as compared to weedy

check indicated an increase equivalent to

81.07% (Table 2). The reason of grain

yield reduction in weedy treatment can be

attributed to the reduction of yield

components including pod number.plant-1,

grain number.pod-1 and 1000-seed weight

due to competition of weeds with

agricultural crop which ultimately reduced

the grain yield (Safahani Langerodi et al.,

2008). This result was consistent with the

research result of (Hamzei et al., 2007).

Oil Content

Obtained results (Table 1) showed no

significant response of oil content to row

spacing, weed control duration and their

interaction. The highest and lowest

amounts of oil content were related to

weed free until emergence in 35 cm row

spacing (40.49 %) and total weedy check

in 35 cm row spacing (39.20 %),

respectively (Table 3). The reason of no

significant effect of row spacing on oil

content is due to the fact that oil content is

a trait with high heritability and less

influenced by environmental conditions

(Abadian et al., 2008). This result was

consistent with the results obtained by

(Ozer, 2003 & Abadian et al., 2007 &

Table 1. Analysis of variance for the effects of row spacing, weed control duration and their interaction on

studied traits for canola

MSC

Oil yield

Oil content (%)

Grain yield

1000-grain weight

Grain no pod-1

Pod no plant-1 df S.O.V

27243.32** 0.002 ns 167974.47** 0.02 ns 118.93** 205.49** 2 Replication

535484.71** 1.13 ns 3260400.10** 0.35** 74.80** 3967.32** 1 Row spacing

483162.54** 0.85 ns 2977861.78** 1.17** 65.27** 10926.91** 6 Weed control duration

10326.14** 0.28 ns 72204.36** 0.004 ns 1.21** 82.57** 6 R×W

359.06 0.18 673.79 0.006 0.16 9.35 26 Error

12.47 3.08 14.80 2.92 8.72 6.18 - C.V% * and **:Significant at 5% and 1% probability level, respectively ns: non significant


Table 2. Means comparison of studied traits in different treatments of row spacing and weed control duration

Oil yield (kg ha-1)

Oil content (%)

Grain yield (kg ha-1)

1000-grain weight (g)

Grain no pod-1

Pod no plant-1 Treatments

Row spacing 1397.86 a 39.87 a 3504.09 a 3.85 b 24.51 a 129.98 b 25 cm

1172.03 b 39.76 a 2946.85 b 4.03 a 21.84 b 149.42 a 35 cm

Weed control duration

921.14 g 39.32 c 2341.65 g 3.14 e 18.59 g 81.07 g WF0

1024.14 f 40.12 ab 2556.10 f 3.68 d 19.97 f 94.15 f WFvc

1120.05 e 39.83 abc 2810.43 e 3.85 c 21.77 e 126.38 e WFv2

1269.90 d 40.14 ab 3162.69 d 3.95 c 23 d 138.93 d WFv4

1433.15 c 39.60 abc 3618.58 c 4.16 b 25.07 c 164.60 c WFv8

1518.24 b 39.43 bc 3848.79 b 4.28 b 26.34 b 175.03 b WFFB

1708.01 a 40.29 a 4240.07 a 4.49 a 27.46 a 197.73 a CWF

The means with same letter do not have statistically significant difference at 5% probability level.

WFvc, WFv2, WFv4, WFv8 and WFFB: Weed free until the growth stages of emergence, 2-leaf, 4-leaf, 8-leaf and flowering bud initiation WF0:0 day weed free CWF: Complete weed free

Table 3. Means comparison of row spacing × weed control duration interaction on studied traits

Oil yield (kg ha-1)

Oil content (%)

Grain yield (kg ha-1)

1000-grain weight (g)

Grain no pod-1

Pod no plant-1 Treatments

Row spacing×Weed control duration

1081.66 h 39.45 a 2742.97 h 3.1 h 19.35 g 73 i 25 cm× WF0

1181.51 g 39.75 a 2971.53 g 3.56 g 20.74 fg 87.3 h 25 cm× WFvc

1273.07 f 40.08 a 3177.05 f 3.75 fg 23.16 de 120.83 f 25 cm× WFv2

1355.24 e 40.22 a 3368.5 e 3.86 def 24.21cd 132.07 e 25 cm× WFv4

1507.84 c 39.76 a 3793.33 c 4.04 cde 26.63 b 151d 25 cm× WFv8

1603.0 b 39.64 a 4042.98 b 4.19 bcd 28.13 a 162.04 c 25 cm× WFFB

1782.69 a 40.22 a 4432.27 a 4.41 ab 29.32 a 183.27 b 25 cm× CWF

760.62 k 39.20 a 1940.33 k 3.19 h 17.82 h 89.13 h 35 cm× WF0

866.76 j 40.49 a 2140.67 j 3.80 efg 19.21gh 101 g 35 cm× WFvc

967.03 i 39.57 a 2443.81 i 3.94 def 20.38 fg 131.93 e 35 cm× WFv2

1184.56 g 40.06 a 2956.88 g 4.04 cde 21.78 ef 145.80 d 35 cm× WFv4

1358.46 e 39.44 a 3443.83 e 4.27 bc 23.52 d 178.2 b 35 cm× WFv8

1433.46 d 39.22 a 3654.60 d 4.37 ab 24.55 cd 187.67 b 35 cm× WFFB

1633.32 b 40.35 a 4047.87 b 4.56 a 25.59 bc 212.2 a 35 cm× CWF The means with same letter do not have statistically significant difference at 5% probability level.

WFvc, WFv2, WFv4, WFv8 and WFFB: Weed free until the growth stages of emergence, 2-leaf, 4-leaf, 8-leaf and flowering bud initiation

WF0:0 day weed free

CWF: Complete weed free


Yazdifar et al., 2007), but was inconsistent

with results obtained by (Eilkaee & Emam,

2003 & Fathi et al., 2002). They believed

that oil content in canola is inversely

related to seed size and decreases by

reduction in pod numbers and relative

increasing of seed size in higher densities.

The reason of no significant differences

between control and interference

treatments in oil content can be explained

by the fact that oil content is a polygenetic

trait and is controlled by many genes, so it

is unlikely that all genes exposed to

environmental stress tend to weed

competition (Shahvardi et al., 2002). This

result was consistent with the results

obtained by (Khoshnam, 2007 & Hamzei

et al., 2007).

Oil Yield



on oil yield were significant (P<0.01). In

addition, row spacing and weed control

duration had an interaction effect on oil

yield. Weed control duration influenced

maximum oil yield the most in the 25 row

spacing treatment. In other words, decrease

in row spacing and increase in weed

control duration increased oil yield. The

highest and lowest amounts of oil yield

were related to the total weed free check in

25 cm row spacing (1782.69 kg.ha-1) and

total weedy check in 35 cm row spacing

(760.62 kg.ha-1), respectively (Table 3).


decreased oil yield, which this trait in 25

cm row spacing was 19.46% higher than

35 cm row spacing (Table 2). The reason

for this can be explained by the fact that oil

yield is obtained from multiplying the

grain yield in oil percent and is a function

of these components (Abadian et al.,

2008). While oil percentage was not

influenced by different row spacing, oil

yield was directly affected by grain yield

and because of the grain yield of 25 cm

row spacing was higher than 35 row

spacing, oil yield increased in this row

spacing. The result was in agreement with

(Faraji, 2005 & Ozoni Davaji, 2006) which

believed that increase in plant density up to

the optimum level increases the oil yield.

This result was also inconsistent with the

result obtained by (Abadian et al., 2008).

Abadian et al., 2008 believed that row

spacing (plant density) has no effect on oil

yield.

In both row spacing, oil yield in control

treatments showed an uptrend with

increasing duration of weed-free and


check. The lowest harvest index also

related to weedy check in both row

spacings (Table 3). The average of oil

yield in the weed-free check indicated

about 85.42% increase in comparison with

the weedy check (Table 2). The reason of

oil yield reduction in weedy treatment can

be explained by the fact that during weed

competition with crop, seed yield

decreased due to reduction of yield

components including pod number per

plant, grain number per pod and 1000-

grain weight, while oil percent did not

changed. Considering that the oil yield is a

function of grain yield and oil percent,

with no change in oil percent, oil yield was

directly decreased by grain yield. This


result was in agreement with (Khoshnam, 2007 & Hamzei et al., 2007) findings.

REFERENCES

Abadian, H., Latifi, N., Kamkar, B. and Bagheri, B.

2008. The effect of late sowing date and plant

density on quantitative and qualitative

characteristics of canola (RGS-003) in Gorgan.

Journal of Agricultural Sciences and Natural.

Resources 15:78-87 (In Persian with English

summary).

Abdolrahmani, B. 2003. Effects of plant density on

yield and agronomic traits of sunflower cv.

Armavirsky under dryland condition in

Maragheh. Iranian Journal of Crop Sciences

5:216-224 (In Persian with English summary).

Aghaalikhani, M., Yaghoobi, S. R. 2008. Critical

period of weed control in winter canola

(Brassica napus L.) in a semi-arid region.

Pakistan Journal of Biological Sciences

11:773-777.

Ali, Y., Ahsanul Hag, M., Tahir, G. R. and Ahmad,

N. 1999. Effect of inter and intra row spacing

on the yield and yield components of chickpea.


2:305-307.

Ball, R. A., Purcell, L. C. and Vories, E. D. 2000.

Optimizing soybean plant population for a

short-season production system in the southern

USA. Crop Science 40:757-764.

Eftekhari, A., Shirani Rad, A. H., Rezai, A. M.,

Salehian, H. and Ardakani, M. R. 2005.

Determining of critical period of weed control

in soybean (Glycine max L.) in Sari region.

Iranian Journal of Crop Sciences. 7: 347-364

(In Persian with English summary).

Eilkaee, M. N., Emam, Y. 2003. Effect of plant

density on yield and yield components in two

winter oilseed rape (Brassica napus L.)

cultivars. Iranian Journal of Agricultural

Sciences 34:509-515 (In Persian with English

summary).

Faraji, A. 2005. Evaluation of the effect of sowing

date on grain and oil yield and yield

components of four canola genotypes in

Gonbad. Iranian Journal of Crop Sciences

7:189-202 (In Persian with English summary).

Fathi, G., Banisaidy, A., Siadat, S. A. and

Ebrahimpoor, F. 2002. Effect of different

levels and plant density on grain yield of

rapeseed , cultivar pf 7045 in Khuzestan

conditions. The Scientific Journal of

Agriculture 25:43-58.

Fernando, H. A., Calvino, P., Cirilo, A. and

Barbieri. P. 2002. Yield responses to narrow

rows depend on increased radiation

interception. Agronomy Journal 94:975-980.

Haddadchi, G. R., Gerivani, Z. 2009. Effects of

phenolic extracts of canola (Brassica napus L.)

on germination and physiological responses of

soybean (Glycine max L.) seedlings.

International Journal of plant production,

3:1.63-74.

Hamzei, J., Dabbagh Mohammady Nasab, A.,

Rahimzadeh Khoie, F., Javanshir, A. and

Moghaddam, M. 2007. Critical period of weed

control in three winter oilseed rape (Brassica

napus L.) cultivars. Turkish Journal of

Agriculture. 31:83-90.

Keramati, S., Pirdashti, H., Esmaili, M. A.,

Abbasian, A. and Habibi, M. 2008. The critical

period of weed control in soybean (Glycine

max (L.) Merr.) in north of Iran conditions.

Pakistan Journal of Biological Sciences.

11:463-467.

Khoshnam, M. 2007. Effect of planting distances

on critical period of weed control in canola

(Brassica napus L.) . M.Sc. Thesis. Faculty of

Agriculture College, Guilan University. Iran.

Pp:86. (In Persian with English summary).

Leach, J. E., Stevenson, H. J., Rainbow, A. J. and

Mullen, L. A. 1999. Effects of high plant

populations on the growth and yield of winter

oilseed rape (Brassica napus L.). Journal of

Agricultural Science 132:173-180.

Majnon Hosseini, N., Alizade, H. M. and Malek

Ahmadi, H. 2006. Effects of plant density and

nitrogen rates on the competitive ability of

canola (Brassica napus L.) against weeds.


Journal of Agricultural Science and

Technology 8:281-291.

Ozer, H. 2003. The effect of plant population

densities on growth, yield and yield

components of two spring rapeseed cultivars.

Plant and Soil Environment. 49:422-426.

Ozoni Davaji, A. 2006. Effects of plant density and

planting pattern on yield, yield components

and growth indices of apetalous flowers and

petalled rapeseed (Brassica napus L.). M.Sc.

Thesis. Faculty of Agriculture College, Guilan

University. Iran. Pp:133.(In Persian with

English summary).

Rahman, I., Ahmad, H., Serajuddin, I., Ahmad, I.,

Abbasi, F., Islam, M. and Ghafoor. S. 2009.

Evaluation of rapeseed genotypes for yield and

oil quality under rainfed conditions of district

Mansehra. African Journal of Biotechnology

8:6844-6849

Roshdy, A., Shams El-Din, G. M., Mekki, B. B.

and Elewa, T. A. A. 2008. Effect of weed

control on yield and yield components of some

canola varieties (Brassica napus L.).

American-Eurasian Journal of Agricultural&

Environmental Sciences 4:23-29.

Safahani Langerodi, A., Kamkar, B., Zand, E.,

Bagherani, N. and Bagheri, M. 2008. Reaction

of grain yield and its components of canola

(Brassica napus L.) cultivars in competition

with wild mustard (Sinapis arvensis L.) in

Gorgan. Iranion Journal of Crop Sciences

9:356-370. (In Persian with English summary).

Salehi, B. 2004. Effect of row spacing and plant

density on grain yield and yield components in

maize (cv. Sc 704) in Miyaneh. Iranian

Journal of Crop Sciences. 6:383-394. (In

Persian with English summary).

Sedghi, M., Seyed Sharifi, R., Namvar, A.,

Khandan-e-Bejandi, T. and Molaei, P. 2008.

Responses of sunflower yield and grain filling

period to plant density and weed interference.

Research Journal of Biological Sciences

3:1048-1053.

Shahvardi, M., Hejazi, A., Rahimian Mashhadi, H.

and Torkamani, A. 2002. Determination of the

critical period weed control in sunflower

(Helianthus annuus cv. Record). Iranian

Journal of Crop Sciences 4:152-162. (In

Persian with English summary).

Shekari, F., Javanshir, A. 2000. Enhancement of

canola seed germination and seedling

emergence water potential by priming. Journal

of Field Crop (Turkish) 5:54-60.

Svecnjak, Z., Varga, B. and Butorac, J. 2006. Yield

components of apical and subapical ear

contributing to the grain yield responses of

prolific maize at high and low plant

populations. Journal of Agronomy and Crop

Science. 192:37-42.

Tollenaar, M., Dibo, A. A., Aguilera, A., Weise, F.

and Swanton. C. J. 1994. Effects of crop

density on weed interference in maize.

Agronomy Journal 81:591-595.

Turgut, L., Duman, L., Bilgili, U. and Acikgoz, E.

2005. Alternate row spacing and plant density

effects in forage and dry matter yield of corn

hybrids (Zea mays L.). Journal of Agronomy

and Crop Science 191:140-151.

Yasari, E., Patwardhan, A. M., Ghole, V. S., Omid,

G. C. and Ahmad. A. 2008. Relationship of

growth parameters and nutrients uptake with

canola (Brassica napus L.) yield and yield

contribution at different nutrients availability.


11:845-853.

Yazdifar, S., Amini, I., Ramea, V. 2007. Evaluation

of row spacing and seed rates effects on yield,

yield components and seed oil in spring canola

(Brassica napus L.) cultivar. Journal of

Agricultural Sciences and Natural Resources

13:58-65. (In Persian with English summary).

Yazdifar, SH., Ramea, V. 2009. Effects of row

spacing and seeding rates on some

agronomical traits of spring canola (Brassica

napus L.) cultivars. Journal of Central

European Agriculture 10:115-121.


چكيده

-88آزمايشي در سال زراعي هاي هرز بر عملكرد، اجزاي عملكرد و درصد روغن كلزا، به منظور بررسي اثرات فاصله رديف كاشت و مدت كنترل علف

. تكرار در موسسه تحقيقات برنج كشور واقع در شهرستان رشت به اجرا درآمد 3به صورت فاكتوريل در قالب طرح بلوك هاي كامل تصادفي در 1387

شامل وجين دستي تا پايان مراحل سبز (سطح 7و كنترل علف هاي هرز در ) نتي مترسا 35و 25(سطح 2فاكتورهاي آزمايشي شامل فاصله رديف در

دو . پس از اين مراحل، به علف هاي هرز اجازه رقابت با گياه زراعي داده شد. بود) گل هاي جوانه) تشكيل(برگي و ظهور 8برگي، 4برگي، 2شدن،

صفات ارزيابي شده شامل تعداد خورجين در بوته، تعداد دانه در خورجين، وزن هزار . رفته شدندتيمار تداخل و كنترل كامل نيز به عنوان شاهد در نظر گ

نتايج نشان داد كه فاصله رديف هاي كاشت مختلف اثر معني داري بر تمامي صفات به جز . روغن و عملكرد روغن بود) مقدار(دانه، عملكرد دانه، درصد

ساير صفات با افزايش فاصله رديف كاشت، .همراه بودشت با افزايش تعداد خورجين در بوته و وزن هزاردانه افزايش فاصله رديف كا. درصد روغن داشت

. عالوه بر اين، افزايش مدت كنترل علف هاي هرز، تمامي صفات به جز درصد روغن را به طور معني داري افزايش داد. به طور معني داري كاهش يافتند

بر اساس نتايج، بيشترين . نترل علف هاي هرز نيز بر تمامي صفات به جز درصد روغن و وزن هزار دانه معني دار بودمدت ك× فاصله رديف برهمكنش

سانتي 35سانتي متر در تيمار كنترل كامل بوده و كمترين ميزان اين صفات نيز به فاصله رديف 25مقدار عملكرد دانه و روغن مربوط به فاصله رديف

. كامل اختصاص داشت متر در تيمار تداخل

ميزان روغن، كلزا، دانهفاصله رديف، مدت كنترل علف هاي هرز، عملكرد : كليديكلمات


Timing of Velvetleaf M

Z. Hatami Moghadam

Departement of of Agriculture and Natural Resources Gorgan University

(Received 12 March 2010; returned 20 December 2010; accepted 25 May 2011)

ABSTRACT

Velvetleaf (Abutilon theophrasti

soybean fields. To the aim of this study is to determine the critical period of velvetleaf control

in two cultivars of soybean, Williams as indeterminate and Persian as determinate,with

different growth patterns. . Theexperiment was conducted at the University of Agricultur

Natural Resources of Gorgan, Iran in 2007 using a randomized complete block design along

with four replicates. The experiments consisted of two sets of treatments; one set was to keep

the plot weed-free until the growth stages of

beginning of flowering (R1) and beginning of pod set (R

treatments that velvetleaf was allowed to grow within the plot throughout the above

mentioned growth stages. Weedy and weed

effect of control treatments were significant on final height, branch number per plant, leaf

area index, dry matter, yield, and pod number per plant, while seed number in pod and 100

seed weights of soybean were not si

were significant on all traits except 100

equations it was found that the critical period of controlling velvetleaf in both cultivars under

study, considering 5% allowed decrease in yield, was between

DAE, which is approximately from 2

allowed decrease, is the number would be between

approximately 3 to 6-leaf growth stage for both cultivars.

Key word: Soybean, Velvetleaf, yield component, competitive periods


Management in Soybean (Glycine Max

Hatami Moghadam, N. Latifi, H. Rezvani, E. Zeinali

Departement of of Agriculture and Natural Resources Gorgan University of Agriculture and

Received 12 March 2010; returned 20 December 2010; accepted 25 May 2011)

Abutilon theophrasti Medic) is one of the most important warm season weeds in

the aim of this study is to determine the critical period of velvetleaf control


different growth patterns. . Theexperiment was conducted at the University of Agricultur


The experiments consisted of two sets of treatments; one set was to keep

free until the growth stages of 2- leaf (V2), 4- leaf (V4), 6

) and beginning of pod set (R3). The second set was

that velvetleaf was allowed to grow within the plot throughout the above

mentioned growth stages. Weedy and weed-free checks were also included in the study


area index, dry matter, yield, and pod number per plant, while seed number in pod and 100

seed weights of soybean were not significantly affected. The effects of interference treatments

were significant on all traits except 100-seed weights. Using the Gompertz and Logistic


nsidering 5% allowed decrease in yield, was between 260 to 943 CGDD or 14

DAE, which is approximately from 2-leaf stage to beginning of flowering. With a 10%

allowed decrease, is the number would be between 320 to 752 CGDD or 18

leaf growth stage for both cultivars.

Soybean, Velvetleaf, yield component, competitive periods

Max (L) Merrill)

of Agriculture and Natural Resources

is one of the most important warm season weeds in

the aim of this study is to determine the critical period of velvetleaf control


different growth patterns. . Theexperiment was conducted at the University of Agriculture and


The experiments consisted of two sets of treatments; one set was to keep

), 6- leaf (V6) stages,

. The second set was interference

that velvetleaf was allowed to grow within the plot throughout the above-

were also included in the study. The


area index, dry matter, yield, and pod number per plant, while seed number in pod and 100-

gnificantly affected. The effects of interference treatments

seed weights. Using the Gompertz and Logistic


260 to 943 CGDD or 14-51

beginning of flowering. With a 10%

320 to 752 CGDD or 18-41 DAE, which is

92 Hatami et al. (2009)/ Iranian Journal of Weed Science 5 (2)

INTRODUCTION

Using herbicides is an important

component of successful soybean

production in modern agriculture and since

many herbicides are available to farmers, a

biological vision should replace the

unconditional use of such herbicides.

Knowing the critical period for weed

control in major crops can aid decision

making on the right timing of weed

removal in cropping systems and

herbicides application (Eyherabide &

Cendoya, 2002). Early research on weed

competition used multiple comparison tests

to calculate the critical period (Zimdahl,

1980). However Cousens, (1988)

suggested that regression analysis is more

appropriate and reliable in calculating the

critical period.

Leaf stages or accumulated thermal units

could improve comparisons because the

leaf appearance rate is highly dependent

upon ambient temperatures (Tollenaar et

al., 1979). Working with this hypothesis

(Hall et al., 1992) determined that in

Canada the beginning of the critical period

for corn widely varied from the 3 to 14 leaf

stages of corn and ended on average at the

14-leaf stage. Wide research show that

there is no stable critical period for weed

control in soybean (Hadizadeh & Rahimian

Mashhadi, 1998). The beginning and

duration of the critical period for weed

control can vary depending on several

factors, including the crop and weed

characteristics, environmental variables

(Hall et al., 1992), cultural practices and

the assumptions made regarding the

methods employed to determine the critical

period for weed control.

For example, the critical period of

Sorghum halopens control in soybean was

determined to be 4-5 weeks after planting

(Williams et al., 1984). The critical period

of weed control in soybean was coinciding

with V2 (with acceptable yield loss of 5%)

in climate condition of Mashhad (Hadizade

& Rahimiyan Mashhadi, 1998). (Chohocar

& Balyan, 1999) reported that this period

in soybean is 30-45 days after sowing and

if weed-free condition was more than 45

days it would have resulted in 74%

increase in grain yield of soybean. (Van

Acker et al., 1993a) reported that the

critical period of weed control in soybean

is about 30 days after emergence. Fellows

& Roeth (1992) show that the onset of the

critical period of weed competition in

soybean may be earlier than 2 weeks or

later than 6 weeks after emergence.

Competitive crop cultivars are important

matters of an integrated weed management

program, they must have high leaf area

index (LAI), height and dry matter

accumulation during the reproductive

period strongly affecting yield

components. Decreasing leaf area of plant

is one of the consequences of interference

of weeds in relation to yield reduction.For

example (Akey et al., 1990) reported that

although soybean was taller than velvetleaf

during early growth period but fast growth,

high transition rate and more partitioning

of photosynthesis to the stems in velvetleaf

resulted in leaf senescence of lower part

and more branching in upper part of

velvetleaf. Thus soybean was not

successful in competition. Kropff et

Timing of velvetleaf management in soybean … 93

al.,(1992) showed that leaf area index

(LAI), leaf area growth rate, specific leaf

area, and height increase determine the

outcome of competition between sugar

beet (Beta vulgaris L.) and common

lambsquarters (Chenopodium album L.). In

a simulation study Weaver et al. (1992)

found that taller corn hybrids with greater

leaf area index and dense canopy of tomato

(Lycopersicon esculentum) had greater

tolerance to velvetleaf (Abutilon

theophrasti) (Lindquist & Mortensen,

1998; Lindquist et al., 1998).

Forcella, (1987) found that a tall fescue

genotype with enhanced leaf area

expansion was more able to maintain yield

when competing with velvetleaf. Wheat

(Challaiah et al., 1983) and potato (Sweet

et al., 1974) cultivars that had greater LAI

and intercepted more light were found to

suppress weeds better. Barker et al.,(2006)

and Evans et al., (2003a) found biomass

partitioning coefficients of leaves

increased in competition with weed more

than weed-free condition but total biomass

partitioning was less. In the tolerance

mechanism of crops in regards to weeds,

suitable biomass partitioning between

different parts of plant is more important

than total accumulated biomass (Evans et

al., 2003b).

"Williams" and "Persian" are two

commonly used commercial cultivars of

soybean in Iran. Velvetleaf (Abutilon

theophrasti Medic.) is a troublesome

annual weed in many maize and soybean

cropping systems in Gorgan, Iran. This

study was conducted to study timing of

velvetleaf management in two different

cultivars of soybean with different growth

pattern, Williams as indeterminate and

Persian as determinate.


The experiment was conducted in 2007 at

the Experiment Station of Gorgan’s

Agriculture and Natural Resource

University Iran. The soil type was clay

loam, pH of 7.5-8 and 0.5% organic

matter. The land was ploughed and

cultivated before planting. According to

local soil test recommendations, basal dose

of 100 kg/ha phosphates ammonium, 300

kg/ha sulphur and 50 kg/ha urea were

incorporated in to the soil. Seed dormancy

was broken by immersing the seeds into

sulfuric acid of 96%for 20 minute (Lacroix

& Staniforth, 1964).

The experiments consisted of two series of

treatments; the first set was control

treatments that the plots were kept weed-

free until the growth stages of 2, 4 and 6-

leaf stages, beginning of blooming and

beginning of pod set. The second set was

interference treatments that velvetleaf was

permitted to grow within the crop until the

above-mentioned growth stages. Weedy

and weed-free controls were also included

in this study. The experimental design was

a randomized complete block with four

replications for the Williams and Persian

cultivars.

Before planting soybean, treated velvetleaf

seeds were planted symmetrically by hand

on 17th of June then field was sprinkler-

irrigated. Seeds of Williams and Persian

cultivars were planted in 8 rows spaced 50

centimeters apart and irrigated up to field

capacity threshold, on 20th of June. After


planting, the entire field was sprinkler-

irrigated till seedling establishment and

furrow-irrigated until 2 weeks prior to

harvest. After seedling emergence,

velvetleaf seedlings were thinned to the

density of 10 plants.m-1 of rows. All

naturally occurring weed species were

removed by hand throughout the growing

season. No herbicides were used before

and after planting or emergence.

Plant Sampling

Parameters such as plant height, leaf area

and plant dry matter for both soybean

cultivars and velvetleaf were measured at

each mentioned growth stages. All

measurements were made on plants in the

middle row of the plots. Height was the

distance from the ground to the highest

leaf. The leaf area of green leaves was

measured using an optical leaf area meter.

At maturity stage,18th October and 10th

October 2006 for Williams and Persian

cultivars, respectively, a 3-m length of the

two central rows of each plot was

harvested by hand to measure grain yield.

Additionally, 100-seed weights were

determined according to the

recommendations of the International Seed

Testing Association (ISTA). At harvest,

number of branches, pods per plant and

number of seeds per pod were measured on

20 randomly selected plants in the center

rows of each plot, except the rows used for

yield measurement.

Data Analysis

Analyses were conducted separately for

each cultivar and data on plant growth

parameters were subjected to analysis of

variance.. Data were analyzed for

comparison of means.(P<0.05) . SAS

statistical software (SAS, 1988) was used

to analyze the data, including analysis of

variance (ANOVA) and comparison of

means based on a LSD procedure (Gomez

& Gomez, 1984).

A logistic model provided the best fit for

the maximum weed-infested period in the

preliminary tests, therefore the model was

also used to describe the effect of

increasing duration of weed infestation on

the yield of soybean (Ratkowsky, 1990) as

follow as

Y = C + D/ (1 + exp (-A + BX)) [1]

Where Y is the yield as a percentage of the

weed-free control, A and B are parameters

that determine the shape of yield falling(A,

is shape of the curve where yield fall is 50

percent and B is shape of the curve in the

minimum of yield), C is the lower yield

asymptote or minimum yield in the

presence of weed interference, D is the

difference between the upper and lower

yield asymptotes, and X is the days after

soybean emergence (DAE) or growth

degree day (GDD), which is equal to weed

infested duration from soybean emergence

time until weed removal and control time.

The Gompertz model was used to describe

the effect of increasing length of weed-free

period on soybean yield (Ratkowsky,

1990):

Y = A exp (-B exp (-KX)) [2]

Where Y is the yield as a percentage of the

weed-free control, A is the upper yield

asymptote or maximum yield in the

absence of weed interference, B and K are

parameters that determine the shape of

yield rising, and X is DAE or GDD, which

is equal to the weed-free period from


soybean emergence time. The critical

period for velvetleaf control in soybean in

regard to DAE or GDD was calculated for

specific yield loss level of 10 and 5% for

each cultivar. Relationship between

soybean seed yield percentage and

velvetleaf dry weight, and height, was

obtained using of segmented models for

both cultivars.


Soybean Leaf Area

Reduction in maximum leaf area index

(LAI Max) was found in both cultivars due to

increased length of the velvetleaf

interference period and leaf area index.

The effects of control treatments until 2-

and 4-leaf stages were significant on

maximum leaf area index of soybean while

in interference treatments up to V2 and V4

there was no significant effect on LAIMax

in both cultivars when compared with the

control (Table 1). Velvetleaf left beyond 4-

leaf stage of soybean showed increase in

LAI more than that of soybeans which

could indicate of a one set competition.

Leaf area index defines the ability of

canopy to intercept PPFD and is an

important factor in determining DM

accumulation. Thus, any reduction in LAI

below the canopy implies less PPFD

interception and influences yield directly

(Loomis et al., 1968). Because velvetleaf

has broad and wide leaves and produces

most of its leaves above the soybean`s

canopy, asuccessful strategy in the

competition for light (Regnier & Harrison,

1993; Rajcan & Swanton, 2001). In this

experiment, a longer presence of velvetleaf

in the plots led to decrease in soybean

yield when compared to the weed-free

control.

In our study maximum LAI of soybean

coincided approximately with pod set stage

which had a polynomial equation (R2=80)

with soybean yieldin both cultivars (Figure

1).

Figure 1. Relationship between Maximum leaf area index of soybean and soybean percent yield compared to

weed-free check (Y = -2.4387X2 + 37.97X – 45.6, R2 = 0.80)

Eik andHanway (1966) also reported high

positive linear correlation between leaf

area of corn at silking and final grain yield.

Evans et al., (2003a) found that the

relationship between grain yield and

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8

LAI max of soybean

yiel

d (%

of w

eed-

free

che

ck )


maximal leaf area was not linear but was

positively correlated (R2= 0.90).

Height and Dry Matter

An overall ANOVA indicated significant

effect of control and interference

treatments on the soybean dry matter and

height (P < 0.0001) (data not shown).

Increasing length of the weed interference

period led to increased height of soybean.

The highest soybean height belonged to

weedy check that was 27% which is 38%

more than weed-free check for Persian and

Williams cultivars, respectively (Table 1).

In this study, more height and shading of

velvetleaf led to increase in soybean height

in the interference treatments. Higher

competition for light in the interference

treatments resulted in increase in crop

eight which is brought about by the change

of light quality for the crop (reduced R/FR

ratio) (Rajcan & Swanton, 2001; Kropff et

al., 1993; Berkowitz, 1987). It seems that

increase of soybean height is due to

increase of internodes distances, and not to

the increase of number of nodes (Akey et

al., 1990). Previous studies showed that in

high competitive situation as internodes

distances increase, the number of

internodes which are the potential positions

for branching and reproductive organs

decrease, which this case is important for

final grain yield (Adelusi et al., 2006;

Domiguez & Hume, 1978).

The final height of velvetleaf when

compared with soybean height in weedy

and weed-free controls was 2.3 and 2.9

times more than Persian cultivar and 2 and

2.5 times more than Williams cultivar,

respectively.

In this study, increase in velvetleaf height

resulted in severe decrease in soybean

yield so when velvetleaf height reached to

60% of maximum height in weedy check

the reduction of soybean yield was 93%

when compared with weed-free check

(Figure 2).

Figure 2. Relationship between height of velvetleaf and soybean percent yield compared to weed-free check

(Y = 94.2314 – (1.454 × X), X0 = 60, R2 = 0.95)

Ngoujio et al.,(2001) reported that in the

competition between velvetleaf and

tomato, velvetleaf was taller than tomato

during the growing season despite tomato

reaching its maximum height. Weaver et

al., (1992) found that duration of the weed-

free period in the plant was mainly

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Height of velvetleaf (% of weedy check )

Soy

hean

yie

ld (

% o

f wee

d-fr

ee c

heck

)


dependent on the height and leaf area

expansion of the weed.. The experiments

also showed that taller weeds caused more

yield losses in crop. Stoller & Woolley

(1985) showed that a major strategy of

velvetleaf for light-competition is the

placement of leaves above the competing

plants (over-topping), in a short crop, such

as soybean, which requires a rise in height.

Dry matter differences of soybeans in

various interferences and control periods

were significant (p < 0.0001). In both

cultivars, significant loss in total soybean

dry weight began when weed removal was

delayed until V6, and the cause would be

rapid increase in velvetleaf dry weight and

its LAI. Dry matter accumulation of

soybeans in the interference treatments til

V6, R1, R3 stages in weedy check compared

with free check, were 42, 60, 80 and 82.4%

less for Persian cultivar and 28, 38, 54, and

60% less for Williams cultivar (Table 1).

Weed-infested conditions for the entire

growing season led to 60 an 82% reduction

in soybean dry weight, compared with full-

season weed-free treatments, of Williams

and Persian cultivars, respectively (Table

1). Traore et al., (2003) in grain sorghum,

and Ngouajio et al., (2001) in tomato,

found that dry matter accumulation in

different cultivars grown in the presence of

weed was drastically reduced compared to

cultivars grown in free weed conditions.

In control weedy treatments, reduction of

soybean dry matter when weed was not

controlled until V2 and V4 stage was

significant in Williams and Persian

cultivars, respectively (Table 1). Soybean

competition was good enough to prevent

dry matter losses when weeds germinated

beyond V2 and V4 stages in the Williams

and Persian cultivars, respectively. Bedmar

et al., (1999) mentioned that weed biomass

at harvest was reduced when corn was kept

weed free for 10-20 days after emergence

(5-6 leaf corn stage). Bhan & Kukula

(1987) pointed out that beneficial effect of

reduced weed competition is apparent from

the increased dry matter accumulation in

chickpea, which is ultimately reflected in

seed yield. Reduction of crop yield as a

response to increasing weed dry weight has

been reported in many researches (Adelusi

et al., 2006; Knezevic et al., 2003;

VanAkcer, 1992).

In this study also the soybean yield was

decreased by increasing the velvetleaf dry

weight. The reduction trend of soybean

yield against velvetleaf biomass in the two

cultivars were similar, which a segmented

model was fit for data from both cultivars

(Figure 3).

Deduction of soybean yield will be

beyond 88%, if velvetleaf biomass reaches

to 650 g m-2, while further increase in

velvetleaf biomass has no further effect on

the reduction of soybean yield (Figure 3).


Figure 3. Relationship between biomass of velvetleaf and soybean percent yield compared to weed-free check

(Y = 88.888 – (0.119 × X), X0 = 650, R2 = 0.97)

Overall, 1% of soybean seed yield was lost

for every 7.3 g/m-2 increase in velvetleaf

dry weight.

In both cultivars under study, few weeds

emerged after the two-leaf and four-leaf

stages of soybean, and those that did

emerge accumulated little shoot biomass.

The canopy closure by the soybean may

have prevented the weeds from

establishment after the two-leaf and four-

leaf stages in Williams and Persian

cultivars, respectively. Weed biomass

proved to be a better indicator of weed

interference than weed density (Wooley et

al., 1993). Strahan et al. (2000) reported

that by increasing period of interference,

weed dry weight increased which will

decrease by increasing control period. In

addition, weed biomass accumulation at

harvest was dramatically reduced when

soybean was kept weed free til at least the

V2 and V4 stage of growth.

Few weed seedlings emerged after these

stages of growth and were not considered

to represent a problem for mechanical

harvesting.

Williams Persian

Treatments Soybean leaf area index

Soybean height

Soybean dry weight Soybean leaf area index

Soybean height Soybean dry weight

WF V2 77 b 122a 63 b 74 b 121.7 a 50 b WF V4 87 ab 118 b 88 a 77 b 96 b 62 b WF V6 96 a 101 c 89 a 91a 95.8 b 100 a WF R1 98 a 98 c 100 a 98 a 97 b 104 a WF R3 00 a 100 c 98 a 99 a 104 ab 102 a WFC 100a 100 c 100 a 100 a 100 b 100 a WI V 2 99 a 109 c 99 a 100 a 101 b 100 a WI V 4 98 a 105 c 98 a 97 a 95 b 90 a WI V 6 72 b 117 b 72 b 67 b 103 ab 58 b WI R 1 61 c 130 a 62 b 59 c 123 a 40 b WI R 3 50 d 133a 46 c 48 d 118 ab 20 c WC 48 d 138 a 40 c 45 d 127 a 18.6 c

WFC, weed-free control. WC, weedy control (unweeded for all of the season)

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200 1400

Velvetleaf biomass

So

ybea

n y

ield

(%

0f w

eed

-fre

e ch

eck)

(gr/m2)

Table 1. Percentage values of weed-free control for morphological traits under different weed-free (WF) and weed-

infested (WI) treatments assessed at soybean harvest for two cultivars


Soybean Yield and Yield Components

Grain yields (% of weed-free check)

resulting from the different periods of

weed competition in both cultivars are

shown in table 2. Highly significant (P <

0.001) differences were found between

treatments in both cultivars. The weedy

control gave a 76 and 90% reduction

compared to weed- free treatment in

Williams and Persian, respectively.

Higher grain yield mean was observed in

weed-free check of Williams that was 30%

more than Persian cultivar (data not

shown).

In both cultivars reduction in grain yield

was the result of, increase in length of the

weed interference period, simultaneous

reduction in plant dry weight, number of

branches, pods per plant and seed number

per pod (Table 2). This was supported by

significant and positive correlation

between seed yield and plant dry weight,

number of branches, pods per plant and

seed number per pod, in both cultivars

(0.99, 0.85, 0.97, and 0.61, for Williams

and 0.97, 0.89, 0.91, and 0.59 for Persian).

A similar result was reported for soybean,

where weed interference also occurred

mainly through the reduced number of

pods and branches per plant (Orwick &

Schreiber, 1979; VanAcer et al.,1993b;

Chhokar & Balyan,1999).

In this study, averaged weight of 100-seed

was not significantly reduced by velvetleaf

interference and thus there was no

significant correlation between the 100-

seed weight and seed yield (0.32 and 0.15

for Williams and Persian cultivars,

respectively).

There was a significant difference in the

averaged seed number per pod in the

weedy check for Persian cultivar, and in

weedy check and interference until R3 for

Williams, when compared with their free

control treatments.

Reduction trend of seed number per pod

may be because of miscarriage of ovum,

tiny seeds and also less seed loading which

led to increase percentage of single seed

per pod. Apparently, seed number per pod

has nospecial effect on changes in grain

yield as a result of velvetleaf interference.

This was supported by small correlations

between seed yield and seed number per

pod (0.61 and 0.54 for Williams and

Persian cultivars, respectively).

The average number of pods per plant of

either cultivar was significantly decreased

by increasing duration of weed interference

after planting. The reduction in pod

number per plant due to weed interference

varied between cultivars.

In Persian, the reduction in pod number by

increase in duration of velvetleaf

interference was greater than in the

Williams (data not shown).This is

supported by (Kelly et al., 1987) who

found that indeterminate cultivars (as a

group) had greater yield stability than

determinate cultivars. These results are in

agreement with work by (Adams, 1967 &

Bennet et al., 1977) which showed that the

greatest negative response to stress during

bean development occurred in the pod

number. Pod number per plant is the first

yield component determined in the

reproductive phase followed by seeds per

pod and seed weight (Adams, 1967). Thus


pod number per plant is likely the most

sensitive yield component to weed

interference. The findings of the present

study showed that grain yield and number

of pods per plant were affected by

velvetleaf interference. Hagood et al.

(1980) reported that 1.4–40 density of

Abutilon theophrasti plants per square

meter decreased number of pods in plant.

These results indicate that the 100-seed

weight is not significantly affected by

interference and control treatments.

Generally in interference treatments

because of decrease in pod number per

plant, assimilates were distributed within

less pods and thus the 100-seed weight

showed no differences when compared

with control treatments in which pod

number per plant was increased because of

favorable conditions, therefore assimilates

were distribute within more pods.

In Williams, seed yield was 76% less when

velvetleaf was allowed to compete all

season long, in comparison to velvetleaf

control in the full season. When velvetleaf

introduction was delayed till the 6-leaf

stage, soybean seed yield increased by

45%. Similar yield values were observed

with the other introduction periods (V6 to

R3) (Table 2). These data suggest that if

velvetleaf competition is delayed til V6 or

later, soybean seed yields would not be

significantly reduced. Other researchers

have recorded similar yield trends when

johnsongrass (Sorghum halepense Pers.)

and smellmelon (Cucumis melo)

emergence is delayed in corn and cotton,

respectively (Ghosheh et al., 1996; Tingle

& Steele, 2003).

Soybean effectively competed with

velvetleaf till V4 before a yield loss was

observed. When velvetleaf was allowed to

compete with soybean at V6, R1, R3, and

during full season, soybean seed yield

reduced 33 to 76%.

These data suggest that effective control

measures should be implemented before

the6-leaf stage (Table 2). Croster and

Masiunas, (1998) showed that the best pea

yields resulted when eastern black

nightshade was controlled during the first 2

weeks of the growing season.

In Persian, soybean grain yield with the

velvetleaf present in full season was 90%

less than velvetleaf control in the full

season.

When velvetleaf was allowed to compete

with soybean for only up to 2-leaf stage, a

yield reduction of 6 and 4% was observed

for Persian and Williams cultivars,

respectively (Table 2). Gargouri and Seely

(1972) reported 10 to 44% pea yield losses

when wild oat were removed 2 or 4 weeks

after emergence, but with weed removal

before these stages no seed yield loss was

observed .Here we provide additional

evidence that early velvetleaf control is

crucial for optimal soybean yield.


Williams Persian

Treatments Branches/ plant

Pods/ plant

Seeds/ pod

100-seed weight

Soybean grain yield

Branches/ plant

Pods/ plant

Seeds/ pod

100-seed weight

Soybean grain yield

WF V2 66 c 42 c 96 a N.S 40 c 28 b 33 b 96 a N.S 29 c WF V4 74 b 65 b 97 a N.S 63 b 83 a 56ab 100 a N.S 84 b WF V6 101 a 99 a 99 a N.S 85 a 89 a 88 a 96 a N.S 93 a WF R1 102 a 101a 98a N.S 92 a 89 a 95 a 99 a N.S 102 a WF R3 100 a 100a 99 a N.S 99 a 82 a 83 a 101 a N.S 98 a WFC 100a 100a 100a N.S 100 a 100 a 100a 100 a N.S 100 a WI V 2 104 a 98 a 99 a N.S 96 a 96.7 a 99 a 102 a N.S 94 a WI V 4 102 a 97 a 100a N.S 90 a 99 a 89 a 96 a N.S 88 a WI V 6 68 b 70 b 98 a N.S 67 b 88 a 47 b 99 a N.S 55.5 b WI R 1 56 c 52 c 95 a N.S 41 c 44 b 34 c 100 a N.S 30.7 c WI R 3 54 c 39 c 83 b N.S 28 d 21 bc 22 d 100 a N.S 12 d WC 49 c 36 c 79 b N.S 24 d 14 c 18 d 87 b N.S 10 d

The Gompertz and Logistic models

generally described the data well, as

indicated by the C.V and R2 values (Table

3). Cousens, (1988) suggested the

Gompertz equation is useful to describe the

relationship between the lengths of the

weed control and grain yield. Hall et al.,

(1992) also suggested the use of Logistic

equation for determination of the influence

of increase in duration of weed

interference on yield. The crop

developmental stage at which weed

interference occurs is an important factor

in determining potential yield losses.

The length of weed-free period, required to

prevent yield loss, varied for the different

cultivars and accepted levels of yield loss

(Table 4). If a 5% yield loss gives a

marginal benefit compared with the cost of

weed control, so the beginning of the

weed-free period required to prevent more

than a 5% yield loss ranged from 260 to

431 CGDD (approximately 14 to 24 DAE

or 2-3 leaf stages) when a yield loss of

10% was acceptable, beginning of the

weed-free period ranged from 320 to 528

CGDD (approximately 18-29 DAE or 3-4

leaves) for Persian and Williams cultivars,

respectively (Table 4; Figure 4). Prior to

these times, velvetleaf presence did not

influence the soybean seed yield.

Soybean growth and development are

sufficiently plastic at 2 to 4-leaf stages to

recover yield potential after velvetleaf is

removed. In other crops, it has been also

reported that weed interference can be

tolerated up to a certain period before it

causes irrevocable yield loss (Dawson,

1986). In our study, the end of the critical

period of velvetleaf interference to prevent

more than > 5% crop yield loss ranged

from 770 to 943 CGDD (approximately 42

to 51 DAE or 7- leaf stage to R1) and for

less than 10% crop yield loss was from 643

to 752 CGDD (approximately 35 to 41

DAE or 5- to 6-leaf stage) for Persian and

Williams cultivars, respectively (Table 4;

Figure 4). These stages coincided with the

soybean canopy closure in both cultivars.

The few weeds emerging after the

mentioned stages accumulated little shoot

biomass and did not affect the seed yield.

Soybean canopy closure may have reduced

both establishment and competitive ability

WFC, weed-free control. WC, weedy control (unweeded for all of the season) N.S: Non Significant

Table 2. Percentage values of weed-free control for Soybean yield and yield components under different weed-free

(WF) and weed-infested (WI) treatments assessed at soybean harvest for two cultivars


of later emerging weeds. Other researchers

have also reported that the establishment

and competition of weeds were reduced

following crop canopy closure (Swanton &

Weise, 1991; Malik et al., 1993; Martin et

al., 2001).

In general, the critical time for weed free

condition varied between cultivars and

accepted percentage of yield lose. The

length of the critical period of velvetleaf

required in Williams cultivar to prevent

yield loss, was somewhat less than the

Persian cultivar probably due to difference

in their growth habit. Regardless of

variability in the extent and occurrence of

the critical period of velvetleaf control,

critical period of velvetleaf control for an

accepted yield loss was variable across the

both cultivars and varied between 260 to

943 CGDD or 14-51 DAE, which is

approximately from 2-leaf stage to

beginning of flowering. Other authors have

reported critical weed-free periods in a

similar range, from 14 to 42 DAE for

soybean in competition with single weed

species (Eaton et al., 1976; Harris and

Ritter, 1987; Stoller et al., 1987; Zimdahl,

1987) and community weeds (Van acker et

al., 1993b; Knezevic et al., 2003). This

weed-free period indicates that duration of

a residual herbicide in soybean need not to

be greater than 51 DAE, or at beginning of

flowering stage of soybean growth, in

order to prevent a yield loss greater than

5%.

Parameter estimates

C.V R2 K B A cultivars

(A)*

0.908 0.95 0.057 (0.0063) 2.16 (0.24) 102.4 (3.05) Williams

1.176 0.91 0.00602 (0.00109) 3.91 (1.22) 99.00 (2.73) Persian

C.V R2 D C B A

(B)**

0.254 0.97 87.48(5.29) 14.03(3.50) 0.14 (0.026) 5.88 (1.13) Williams

0.404 0.94 96.34(5.17) 3.34 (3.08) 0.005 (0.0007) 3.96 (0.57) Persian

Critical duration of weed-infested period Critical duration of weed-free period ALYL a 5% 10% 5% 10%

Cultivars DAE Crop stageb

CGDD DAE Crop stage

CGDD DAE Crop stage

CGDD DAE Crop stage

CGDD

Williams 24 V3 431 29 V4 528 51 R1 943 41 V6 752 Persian 14 V2 260 18 V3 320 42 V7 770 35 V5 643

Table 3. (A) Coefficient estimates (along with standard errors) for the Gompertz equation (increasing

length of weed-free period in the two cultivars). (B) Coefficient estimates (and standard errors) for the

Logistic equation (increasing length of weed-infested period in the two cultivars).

*Where A is the upper yield asymptote or maximum yield in the absence of weed interference, B and K are parameters that determine the shape of the curve or shape of yield rising. **Where A and B are parameters that determine the shape of the curve or shape of yield falling, C is the lower yield asymptote or minimum yield in the presence of weed interference, D is the difference between the upper and lower yield asymptotes.

Table 4. The critical duration of velvetleaf-infested period and the critical length of velvetleaf free period in soybean

in days after crop emergence (DAE), crop development stage and cumulative growth degree day (CGDD), as

calculated by the Gompertz and Logistic equations for each cultivar for 5 and 10% yield loss levels.

a: Accepted Levels of Yield Loss b: According to Fehr and Caviness


Weed control under these conditions

should be based on post-emergence

herbicides and/or cultivation, but if any

yield loss is unacceptable, control practices

must begin as soon as possible after

soybean emergence.

It is suggested that velvetleaf interference

will not reduce soybean yields under

normal environmental conditions if

velvetleaf is controlled in a timely manner

with post-emergence herbicides.

The results showed that soybean tolerates

weed interference till the 2-3 leaves stage,

so post-emergence herbicides must be

sprayed before this stage to control the

weeds effectively. With the aid of known

critical period of weed control it is possible

to avoid unnecessary control

measurements, to give up the use of long

persistent soil herbicides and to use post-

emergence herbicides more consciously,

even with lower doses than recommended

(Knezevic et al., 2002).

Variability in the occurrence of the critical

period of weed control may be attributed to

a number of factors including differences

in growth characteristics of cultivars and

the crops (Burnside, 1979; Zimdahl, 1980).

In this study, since all conditions in the

research were constant (e.g. climate, soil

parameters, agronomic practices and weed

characteristics) therefore the differences in

the critical period of two cultivars is

attributed to characteristics of the cultivar.

As the Persian cultivar was more sensitive

to velvetleaf interference than Williams, it

also had a higher yield reduction. This

information could be used by farmers to

target mechanical weeding operations to

control weeds at the stage with maximum

benefit to the crop.

Conclusions

The results of this study indicate that

velvetleaf is a serious weed problem in

soybean production. The critical period of

weed control, based upon an arbitrary 5%

level of yield loss, varies between 260 to

943 CGDD or 14-51 DAE, which

represents approximately V2 to R1 stages of

the crop growth. We have confirmed that

Figure 4. Soybean yield response to increasing length of velvetleaf-free period (▲) and duration of

velvetleaf infestation(■) in cumulative growth degree day for Williams (A) and Persian (B) estimated from

Gompertz and Logistic equations (statistical information on the regression lines is given in Table 2).


the timing of significant yield loss varies

between two soybean cultivars, as

(Zimdahl, 1988) noted that the critical

period is not an inherent property of the

crop. The variation of weed biomass is in

reverse to variation in crop yield. Increase

in length of interference period led to

reduce in soybean dry weight, number of

branches, pods per plant, seed number per

pod and finally reduction of soybean yield.

Weeds that emerged after the 2- to 4-leaf

soybean stage (14-29 DAE) grow in a

competitive disadvantage in regard to the

crop. The beginning of the critical period

corresponded with the beginning of an

increase in total velvetleaf biomass at the

2- to 4-leaf stage of soybean growth.

Knowledge of the critical period of weed control and the morphological changes occurring in the crop may provide useful information upon future weed control recommendations.

REFERENCE

Adams, M. W. 1967. Basis of yield component

compensation in crop plants with special

reference to the field bean, Phaseoulus

vulgaris. Crop Science 7:505-510.

Adelusi, A. A., Odufeko, G. T. and Makinde, A. M.

2006. Interference of Euphorbia heterophylla

Linn. on the Growth and Reproductive Yield

of Soybean (Glycine max L.) Merill. Research

Journal of Botany 1:85-94.

Akey, W. C., Jurik, T. W. and Dekker, J. 1990,

Competition for light between velvetleaf

(Abutilon theophrasti) and soybean (Glycine

max). Weed Research 31:63-72.

Baghestani, A., Lemieux, C., Leroux, G. D.,

Baziramakenga, R. and Simard, R. 1999.

Determination of allelochemicals in spring

cereal cultivars of different competitiveness.

Weed Science 47:498-504.

Barker, D. C., Knezevic, S. Z. and Lindquist, J. L.

2006. Effect of nitrogen addition

on the comparative productivity of corn and

velvetleaf (Abutilon theophrasti).Weed

Science. 54:354-363.

Bedmar, F., Manett, P. and Monterubbianesi, G.

1999. Determination of the critical period of

weed control in corn using a thermal basis.

Pesq. agropec. bras. Vol.34 no.2 Brasília Feb.

Bennett, J. P., Adams, M. W. and Burga, C. 1977.

Pod yield component variation and

intercorrelation in Phaseolus vulgaris L. as

affected by planting density. Crop Science

17:73-75.

Berkowitz, A. R. 1987. Competition for resource in

weed-crop mixtures. In "Weed management in

agroecosystems: ecological approaches"

Altier, M. A., and Liebman, M. (eds.). CRC.

Press, Boca Raton. FI.

Bhang, V. M. and Kukula, S. 1987. Weeds and

their control in chickpea. In: The Chickpea

(eds M. C. Saxena, and K. B. Singh). 319-328.

C. A. B. International, Wallingford, Oxon,

UK.

Burnside, O. C. 1979. Soybean (Glycine max (L.)

Merr.) growth as affected by weed removal,

cultivar and row spacing. Weed Science

27:562-565.

Callaway, M. B. 1990. A compendium of crop

varietal tolerance to weeds. American Journal

of Alternative Agriculture 7:169-180.

Challaiah, R. E., Ramsel, G. A., Wicks, O. C. and

Johnson, V. A. 1983. Evaluation of

competitive ability of winter wheat cultivars.

Proc. North Cent. Weed Control Conference

38:85-91.

Chhokar, R. S. and Balyan, R. S. 1999.

Competition and control of weeds in soybean.


Christensen, S. 1995. Weed suppression ability of

spring barely varieties. Weed Research

35:241-247.


Cousens, R. 1988. Misinterpretation of result in

weed research through inappropriate use of

statistic. Weed Research 28:281-289.

Croster, M. P. and Masiunas, J. B. 1998. The effect

of weed-free period and nitrogen on eastern

black nightshade competition with English

pea. Hort Science 33:88-91.

Dawson, J. H. 1986. The concept of period

threshold. Pages 327-331 in Proceeding of the

European Weed Research Society

Symposium.Economic Weed Control.

Stuttgart:EWRS.

Domiguez, C. and Hume, D. Y. 1978. Flowering,

abortion, and yield of early-maturing soybeans

at three densities. Agronomy Journal 70:801-

805.

Eaton, B. J., Russ, O. G. and Feltner, K. C. 1976.

Competition of velvetleaf, prickly side, and

Venice mallow in soybean. Weed Science

24:224-228.

Eik, K. and Hanway, J. J. 1996. Leaf area in

relation to the yield of grain corn. Agronomy

Journal 58:16-20.

Evans, S. P, Knezevic, S. Z., Lindquist, J. L.,

Shapiro, C. A. 2003a. Influence of nitrogen

and duration of weed interference on corn

growth and development. Weed Science 51:

546-556.

Evans, S. P, Knezevic, S. Z., Lindquist, J. L.,

Shapiro, C. A. and Blankenship, E. E. 2003b.

Nitrogen application influences the critical

period for weed control in corn. Weed Science

51:408-417.

Eyherabide, J.J. and Cendoya, M.G. 2002. Critical

period of weed control in soybean for full field

and in-furrow interference. Weed Science 50:

162- 166.

Fellows, G. M. and Roeth, F. W. 1992. Shattercane

(Sorghum bicolor) interference in soybean


Forcella, F. 1987. Tolerance of weed competition

associated with high leaf area expansion rate in

tall fescue. Crop Science 27:146-147.

Gargouri, T. and Seely, C. I. 1972. Competition

between spring peas and nine densities of wild

oat (Avena fatua L.) plants. Res. Prog. Rep.

West. Soc. Weed Science. Pp. 102-103.

Ghosheh, H. Z., Holshouser, D. L. and Chandler, J.

M. 1996. Influence of density of Johnsongrass

(Sorghum hallepense) interference in field

corn (Zea mays). Weed Science 44:879-883.

Gomez, K. A. and Gomez, A. A. 1984. Statistical

Procedures for Agricultural Research. New

York: J. Wiley. Pp. 306-309.

Hadizadeh, M. H. and Rahimian, H. 1998. The

critical period of weed control in soybean.

Iranian Journal of Plant Pathology 34:25-29.

Hagood Jr, E. S., Bauman, T. T., Williams Jr, J. L.

and Schreiber, M. M. 1980. Growth analysis of

soybean (Glycine max) in competition with

velvetleaf (Abutilon theophrasti). Weed

Science 28:729-734.

Hall, M. R., Swanton, C. J. and Anderson, G. W.

1992. The critical period of weed control in

grain corn (Zea mays). Weed Science 40: 441-

447.

Harris, T. C. and Ritter, R. L. 1987. Giant green

foxtail (Setaria viridis var. major) and fall

panicum (Panicum dichotomiflorum)

competition in soybeans (Glycine max). Weed

Science 35:663-668.

Kelly, J. D., Adams, M. W. and Vamer, G. V. 1987.

Yield stability of determinate and

indeterminate dry bean cultivars. Theor. Appl.

Genet 74:516-521.

Knezevic, S. Z., Evans, S. P., Blankenship, E. E.,

Van Acker, R. C. and Lindquist, J. L. 2002.

Critical period for weed control: the concept

and data analysis. Weed Science 50:773-786.

Knezevic, S. Z., Evans, S. P. and Mainz, M. 2003.

Row spacing influences the critical timing for

weed removal in soybean (Glycine max). Weed

Technology 17:666-673.

Kropff, M. J., Van Kuelen, N. C., Van Laar, H. H.

and Schniders, B. J. 1993. The impact of

environmental and genetic factors. In

"Modeling crop weed interference". Kropff,


M. J. and H. H. Van laar (eds.). IRRI Book

publisher.

Kropff, M. J., Weaver, S. E. and Smits, M. A. 1992.

Use of ecophysiological models for crop-weed

interference: relation amongst weed density,

relative time of weed emergence, relative leaf

area and yield loss. Weed Science 40:296-301.

Lacroix, L. J. and Staniforth, D. W. 1964. Seed

dormancy in velvetleaf. Weeds 12: 171–174.

Lindquist, J. L. and Mortensen, D. A. 1998.

Tolerance and velvetleaf (Abutilon

theophrasti) suppressive ability of two old and

two modern corn (Zea mays) hybrids. Weed

Science 46:569-574.

Lindquist, J. L., Mortensen, D. A. and Johnson, B.

E. 1998. Mechanism of corn tolerance and

velvetleaf suppressive ability. Agronomy

Journal 90:787-792.

Lomis, R. S., Williams, W. A., Duncan, W. G.,

Dovrat, A. and Nunez, F. 1968. Quantitative

descriptions of foliage display and light

absorption in field communities of corn plants.

Crop Science 8:352-356.

Malik, V. S., Swanton, C. J. and Michaels, T. E.

1993. Interaction of white bean (Phaseolus

vulgaris L.) cultivars, row spacing, seed

density with annual weeds. Weed Science

41:62-68.

Martin, S. G., Van Acker, R. C. and Friesen, L. F.

2001. Critical period of weed control in spring

canola. Weed Science 49:326-333.

Ngouajio, M., McGiffen, M. E. Jr. and Hembree, K.

J. 2001. Tolerance of tomato cultivars to

velvetleaf interference. Weed Science 49:91-

98.

Nieto, J. H., Brando, M. A. and Gonzalez, J. T.

1968. Critical period of the crop growth cycle

for competition from weeds. PANS 14:159-

166.

Orwick, P. L. and Schreiber, A. S. 1979.

Interference of redroot pigweed (Amaranthus

retroflexus) and robust foxtail (Setaria viridis

Var.) in soybeans (Glycine max L.). Weed

Science 27:665-674.

Rajcan, I. and Swanton, C. J. 2001. Understanding

maize-weed competition: resource competition

light and the whole plant. Field Crop Research

71:139-150.

Ratkowsky, D. A. 1990. Handbook of Nonlinear

Regression Models. Marcel Dekker, New

York, USA.

Regnier, E. E. and Harrison, S. K. 1993.

Compensatory responses of common

cocklebur (Xanthium strumarium) and

velvetleaf (Abutilon theophrasti) to partial

shading. Weed Science 41:541-547.

Rose, S. J., Burnside, O. C., Specht, J. E. and

Swisher, B. A. 1984. competition and

allelopathy between soybean and weeds.

Agronomy Journal 76:523-528.

SAS Institute (1998) SAS/STAT. Guide for

Personal Computer, Release 6.04. SAS

Institute Inc., Cary, NC, USA.

Selleck, G. W. and Dallyn, S. L. 1978. Herbicide

treatments and potato cultivar interaction.

Proc. Northeast Weed Science. Soc 32:152-

156.

Staniforth. D. W. 1962. Responses of soybean

varieties to weed competition. Agronomy

Journal 54:11-13.

Stoller, E. W., Harrison, S. K., Wax, L. W.,

Reginer, E. E. and Nafziger, E. D. 1987. Weed

interference in soybeans (Glycine max). Rev.


Stoller, E. W. and Woolley, J. T. 1985. Competition

for light by broadleaf weeds in soybeans


Strahan, R. E., Griffin, J. L., Reynolds, D. B. and

Miller, D. K. 2000. Interference between

Rottboellia cochinchinensis and zea mays.


Swanton, C. J. and Weise, S. F. 1991. Integrated

weed management: The rational and approach.

Weed Technology 5:648-656.

Sweet, R. D., Yip, C. P. and Sieczka, J. B. 1974.

Crop cultivars: can suppress weeds? N. Y.

Food Life Science Q 7:3-5.


Tingle, C. H. and Steele, G. L. 2003. Competition

and control of smellmelon (Cucumis melo var.

dudaim Naud.) in cotton. Weed Science

51:586-591.

Tollenear, M., Daynard, T. B. and Hunter, R. B.

1979. Effect of temperature on rate of leaf

appearance and flowering date in maize. Crop

Science 19:363-366.

Traore, S., Lindquist, J. L., Mason, S. C., Martin,

A. R. and Mortensen, D. A. 2003.

Comparative ecophysiology of grain sorghum

and Abutilon theophrasti in monoculture and

in mixture. Weed Research 42:65-75.

VanAcer, R. C. 1992. The critical period in soybean

and the influence of weed interference on

soybean growth. M. S. Thesis Univ. Guelph,

On. pp.104.

VanAcer, R. C., Weise, C. F. and Swanton, C. J.

1993a. Influence of interference from a mixed

weed species stand on soybean (Glycine max

L.) growth. Canadian Journal of Plant Science

73:1293-1304.

Van Acker, R. C., Weise, S. F. and Swanton, C. J.

1993b. The critical period of weed control in

soybeans (Glycine max (L.) Merr.). Weed

Science 41:194-200.

Warwick, S. I. and Black, L. D. 1988. The biology

of Canadian weeds. 90. Abutilon theophrasti.

Canadian. Journal of Plant Science 68:1069-

1085.

Weaver, S. E. 1984. Critical period of weed

competition in three vegetable crops in relation

to management practices. Weed Research

24:317-325.

Weaver, S. E., Kropff, M. J. and Groeneveld, R. M.

W. 1992. Use of ecophysiological models for

crop-weed interference: The critical period of

weed interference. Weed Science 40: 302-307.

Weaver, S. E. and Tan, C. S. 1983. the critical

period of weed interference in transplanted

tomatoes (Lycopersicum esculentum): growth

analysis. Weed Science 31:476-481.

Wicks, G. A., Nordquist, P. T., Hanson, G. E. and

Schmidt, J. W. 1994. Influence ofwinter wheat

(Triticum aestivum) cultivars on weed control

in sorghum (Sorghum bicolor). Weed Science

42:27-34.

Williams, C. S. and Hayes, R. M. 1984.

Johnsongrass (Sorghum halepense)

competition in soybean (Glycine max L). Weed

Science 32:498-501.

Woolley, B. L., Michaels, T. E., Hall, M. R. and

Swanton, C. J. 1993. The critical period of

weed control in white bean (Phaseolus

vulgaris). Weed Science 41:180-184.

Yip, C. P., Sweet, R. D. and Sieczka, J. B. 1974.

competitive ability potato cultivars with major

weeds. Proc. Northeast Weed Science 35:271-

281.

Zimdahl, R. L. 1988. The concept and application

of the critical weed-free period. Pages 145-155

in M. A. Altiere and M. Libman, ed. Weed

Management in Agroecosystems: Ecological

Application. Boca Raton, FL:CRC Press.

Zimdahl, R. L. 1980. Weed Crop Competition: A

Review. Corvallis, OR: International Plant

Protection Center. 196p.


چكيده

به منظور يافتن دوره بحراني كنترل علف هرز گاوپنبه در دو رقم سويا با . هاي هرز تابستانه در مزارع سويا مي باشدترين علفگاوپنبه يكي از مهم

آزمايشي در دانشگاه علوم كشاورزي ) نامحدود و رقم سحر يا پرشين به عنوان رقم رشد محدودرقم ويليامز به عنوان رقم رشد (الگوهاي رشدي متفاوت

براي تعيين دوره بحراني گاوپنبه از دو . با استفاده از طرح بلوك هاي كامل تصادفي در چهار تكرار صورت گرفت 2007و منابع طبيعي گرگان در سال

بندي سويا، به گاوپنبه اجازه در آنها تا مراحل دو برگي، چهار برگي، شش برگي، اوايل گلدهي و اوايل غالفسري تيمار استفاده شد؛ تيمارهاي تزاحم كه

در كنار اين تيمارها يك تيمار به عنوان شاهد تزاحم در نظر گرفته . هرز كنترل شدندهايتزاحم داده شد و از آن پس تا انتهاي فصل رشد تمامي علف

هرز هايسري دوم، تيمارهاي كنترل بودند كه در آنها تا مراحل رشدي ياد شده علف. ه حضور در تمام طول فصل رشد داده شدشد كه به گاوپنبه اجاز

هرز در طول هايكنترل تمامي علف(اين تيمارها نيز همراه با شاهد كنترل . كنترل و از آن پس به گاوپنبه تا انتهاي فصل رشد اجازه تزاحم داده شد

اثر تيمارهاي كنترل بر ارتفاع نهايي سويا، تعداد شاخه جانبي در بوته، شاخص سطح برگ، وزن خشك، عملكرد و تعداد غالف در هر . ودندب) فصل رشد

غير از اثر تيمارهاي تزاحم نيز بر تمام صفات فوق به. داري نگذاشتبوته سويا معني دار گشت اما بر تعداد دانه در غالف و وزن صد دانه سويا تأثير معني

نتايج اين تحقيق بر اساس معادالت برازش داده . ترين جزء عملكرد به حضور گاوپنبه، تعداد غالف در بوته بودحساس. وزن صد دانه معني دار گرديد

عملكرد مجاز بين كاهش % 5روز رشد، نشان داد كه دوره بحراني كنترل علف هرز گاوپنبه در دو رقم سويا با -شده گامپرتز و لجستيك بر حسب درجه

قرار دارد و در هر دو رقم با ) CGDD 943روز پس از كاشت، معادل 51(تا اوايل گلدهي ) CGDD 260روز پس از كاشت، معادل 14(مراحل دو برگي

ز پس از رو 41(و شش برگي ) CGDD 320روز پس از كاشت، 18(كاهش عملكرد مجاز دوره بحراني بين مراحل سه برگي % 10در نظر گرفتن

.باشدمي) CGDD 752كاشت،

سويا، گاوپنبه، اجزا عملكرد، دوره رقابت: كليديكلمات

بسم اهللا الرحمن الرحيم

راهنماي تنظيم مقاله

هاي هرز و يا علوم علفهاي هرز ارسال مي گردد بايد نتيجه تحقيقات در زمينه هايي كه براي چاپ درمجله دانش علف مقاله

.مجالت ديگر فرستاده نشده باشد وابسته به آن باشد و قبال چاپ و يا همزمان، به

تايپ ) ميلي متر با كامپيوتر 11( سانتي متري از چهار طرف و فاصله سطور دو ماشين 5/2با حاشيه A4مقاله بايد روي كاغذ -1

بايد به آدرس ضمنا نسخه الكترونيكي مقاله نيز. ر سه نسخه ارسال شودوتمام صفحات مقاله پشت سرهم شماره گذاري و د

.ايميل شود [email protected]اينترنتي انجمن

.عنوان مقاله بايدكوتاه و رسا باشد وترجمه انگليسي آن نيز زير عنوان فارسي نوشته شود -2

.نوشته شود) نويسندگان( حقيق زير اسم نويسنده و نام موسسه محل ت) نويسندگان( نام و نام خانوادگي نويسنده -3

.كلمه تجاوز نكند 150هاي تحقيق باشد و حتي االمكان از چكيده مقاله بايد شامل مطالب مهم يافته -4

نتايج و بحث مي تواند در هم . ها، نتايج و بحث تنظيم شود هاي درجه يك شامل مقدمه، مواد و روش متن مقاله با زير عنوان -5

در متن "سپاسگزاري "در صورتي كه الزم باشد از شخص يا سازماني تشكر شود، اين مطلب با زير عنوان درجه يك . ادغام شود

.آورده مي شود) نتايج و بحث( مقاله بعد از بحث

طر جداگانه قرار هاي درجه سه در س گيرد؛ در حاليكه زير عنوان زير عنوان هاي درجه يك و درجه دو در سطر جداگانه قرارمي -6

.شود نگرفته و مطلب با دو نقطه از آن جدا مي

ارقام و اعداد مربوط به اوزان ومقادير در صورتيكه در آغاز جمله بيايد . براي اوزان ومقادير از سيستم متريك استفاده شود -7

.ارقام يك رقمي در هر حال با حروف نوشته شود. باحروف نوشته شود

و در زبان 14و اندازه قلم در زبان فارسي Times New Romanو در زبان انگليسي Bzarنوع قلم در زبان فارسي -8

.باشد 12انگليسي

.باشد 5/1فاصله خطوط متن -9

باحروف (space)هميشه بدون فاصله از حرف يا عدد قبل ولي يك فاصله (;) و نقطه ويرگول) ،(، ويرگول(.)در متن نقطه -10

.دو فاصله رعايت گردد) جز منابع مورد استفاده به( ضمنا پس از نقطه آخر جمله . يا عدد بعدي رعايت گردد

فايل مربوطه نيز جداگانه ذخيره و . باشد (Excel)گردد ترجيحا در نرم افزار اكسل نتايجي كه به صورت شكل تنظيم مي -11

.ارسال گردد

.از عاليم دايره، مثلث، مربع و لوزي به صورت توپر و توخالي استفاده شودبراي رسم نمودارها بهتر است

ها در زير نوشته فارسي آنها درج شود، بطوريكه ها ونگاره ها و شرح شكل هاي جدول ترجمه انگليسي عنوان و زير عنوان -12

.ها و شكل ها قابل استفاده خوانندگان انگليسي زبان نيز باشد اطالعات جدول

اسامي علمي در عنوان و در چكيده بدون اسم نام گذار . اسامي علمي باحروف ايتاليك نوشته و يا زير آنها خط كشيده شود-13

نام علمي در صورت تكرار بدون اسم نام گذار و نام . ولي درمتن مقاله، آنجا كه براي اولين بار ميĤيد با اسم نام گذار نوشته شود

بديهي است اسم نام گذار طبق قواعد مربوط خالصه نوشته . شود و يك نقطه نوشته مي) بزرگحرف ( جنس با حرف اول آن

.شود مي

ها بايد گويا عنوان جدول. را براحتي درمتن آورد) نتيجه(استفاده از جدول، وقتي مجاز است كه نتوان اطالعات بدست آمده -14

اعداد جدول به انگليسي و حتي ا المكان بدون اعشار ودر صورت لزوم تا دو . باشد به نحوي كه نياز نباشد به متن مقاله مراجعه شود

درجدول فقط از خطوط افقي استفاده . اختصارات و عالئم متن جدول را ميتوان با زيرنويس روشن كرد. رقم اعشار داشته باشد

اعداد و ارقام و . قيه قسمتهاي جدول جدا گرددعنوان باالي جدول با دو خط نزديك به هم به فاصله تقريبي يك ميلي متر از ب. شود

طولي يا عرضي ( ها بايد طوري تنظيم شودكه در يك صفحه مجله ابعاد جدول. مطالب جدول نبايد در متن مقاله تكرار شده باشد

.جا بگيرد)

رسي آنها درج شود، بطوريكه ها ونگاره ها در زير نوشته فا ها و شرح شكل هاي جدول ترجمه انگليسي عنوان و زير عنوان -15

.ها قابل استفاده خوانندگان انگليسي زبان نيز باشد ها و شكل اطالعات جدول

.كليه منابع مورد استفاده به زبان انگليسي و مطابق الگوي زير تنظيم شود -16

Shahbazi, H. and Rashed Mohassel, M. 2000. The critical period of weed control in sugar beet. Abstracts of the 6th Iranian crop Production & Breeding Congress, Babolsar, 575.(In Persian).

شود مانند اي است، تمام حروف آن در منابع علمي نوشته مي كه يك كلمه) ادواري( در مورد نام نشريات پيايند-17

Biotechnology اگر نام نشريات بيش از يك كلمه باشد بايد كوتاه شده بعنوان مثالWeed Science بصورتWeed Sci

.نوشته شود

اي به عنوان منبع مورد استفاده قرار گرفته باشد و به زبان غير التين چاپ شده، متن آن به زبان انگليسي ترجمه مي وقتي مقاله -18

.شود در پرانتر قيد مي) مانند فارسي يا ژاپني(بان اصلي آن شود الزم است پس از قيد صفحات، ز

در صورتيكه منبع به زبان غير التين ولي داراي خالصه التين باشد در اين صورت منبع به زبان التين داده شود و در آخر در پرانتر

.(In Persian with English summary)مثال. زبان اصلي قيد گردد

.اي خالصه يا متن كامل به زبان انگليسي باشدمقاالت بايد دار -19

–موسسه تحقيقات گياهپزشكي كشور -ولنجك –تهران : هاي هرز به نشاني كليه مقاالت با پست به دفتر مجله دانش علف -20

.فرستاده شود 1985813111كدپستي –هاي هرز مجله دانش علف -هاي هرز بخش تحقيقات علف

: هاي زير است وتاه علمي شامل بخشساختار يك مقاله ك -21

"هاي كليدي ، مقدمه كوتاه، بدون نوشتن عنوان عنوان فارسي و انگليسي ، نويسنده يا نويسندگان، محل انجام كار، چكيده، واژه

كامل ، چكيده اانگليسي مثل مقاالت )هاي فرعي بدون عنوان( ، نتايج و بحث )هاي فرعي بدون عنوان( ، روش بررسي "مقدمه

.)2حداكثر ( ها و شكل) 2حداكثر ( ها صفحه مجله شامل جدول 4مجله، منابع و اندازه حداكثر

بسم اهللا الرحمن الرحيم

حميد رحيميان، پرديس كشاورزي ومنابع طبيعي، دانشگاه تهران: مدير مسئول

محمدعلي باغستاني، موسسه تحقيقات گياهپزشكي كشور: سردبير

)به ترتيب الفبا(: هيئت تحريريه

دانشگاه گيالن -دانشكده كشاورزي جعفر اصغري،

دانشگاه فردوسي مشهد -، دانشكده كشاورزيمحمدحسن راشد محصل

، دانشكده كشاورزي و منابع طبيعي، دانشگاه تهرانحسن عليزاده

بذر چغندر قند اصالح و تهيه ، موسسه تحقيقاتهيان نوقابيلمحمد عبدال

دانشگاه شيراز-دانشكده كشاورزي ، حسين غديري

دانشگاه اهواز -، دانشكده كشاورزي حسين موسوي نيا

: بررسي كنندگان مقاالت

مجيد آقاعلي خاني، مصطفي اويسي، محمد بازوبندي، محسن بهشتيان، ناصر مجنون حسيني، محمدحسن راشد محصل، مهدي

كريم مجني، رحيم محمديان، حسين نجفي، شهرام نوروز زاده، نوشين راستگو، پرويز شيمي، مجيد عباسپور، جاويد قرخلو، حسن

نظام آبادي، محمدحسن هاديزاده

مرسده تقوي، موسسه تحقيقات گياهپزشكي كشور :منشي مجله

به تاييد وزارت علوم، تحقيقات و 17/12/1382بتاريخ 1224/2910/3 پژوهشي اين مجله طي نامه شماره-درجه علمي �

. سيده استآوري ر فن

. باشد هيئت تحريريه در ويرايش، رد و خالصه نمودن مقاالت دريافتي مجاز مي �

.مقاالت بايد مطابق دستورالعمل مجله تدوين شود �

رسد اين مجله دو بار در سال به چاپ مي �

چاپ توكل : چاپ و صحافي

3پور پالك كوچه نيك - خيابان فخر رازي - خيابان انقالب: آدرس

حق عضويت در اين انجمن، مبلغ . شود هرز ايران رايگان ارسال مي هاي اين مجله براي اعضا انجمن علوم علف

اشتراك ساليانه مجله براي موسسات، . شود تخفيف منظور مي %50باشد ولي براي دانشجويان ريال مي 50000

حساب جاري شماره ك بايد به وجه عضويت و يا اشترا. ريال است 50000ها و غيره ها، شركت كتابخانه

بنام انجمن علوم ) 3420كد (نزد بانك تجارت شعبه دانشگاه شهيد بهشتي تهران 342060803

فرم عضويت و اشتراك در . واريز شده و فيش آن همراه با فرم مربوطه به دفتر مجله ارسال شود هرز هاي علف

.باشد پايگاه اينترنتي انجمن نيز در دسترس مي

هرز، موسسه تحقيقات گياهپزشكي كشور، دفتر مجله دانش علف: نشاني

1985713133كد پستي -1454تهران، صندوق پستي

) 021( 22403695: تلفن و فاكس

[email protected] :آدرس الكترونيكي

www.isws.ir :پايگاه اينترنتي انجمن

............ فرم اشتراك براي جلد

.............................................................................................شركت و غيره/كتابخانه/موسسهنام

: آدرس

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: .......................................................شماره فاكس.............. : ...............................شماره تلفن

:آدرس اينترنتي

Documents

scientificfinding.gau.ac.irscientificfinding.gau.ac.ir/uploading/scientificfinding... · 2013. 7. 21. · Iranian Journal of Weed Science Volume 5 Number 2 2009 Executive Director: