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Cool Season C3-Grasses “Wheat, Rye, Barley, And Oats”Differ In Shoot: Root Ratio When Applied With DifferentNPK SourcesAmanullah a b , B. A. Stewart b & Hidayat Ullah aa Department of Agronomy, Faculty of Crop Production Sciences , Khyber PakhtunkhwaAgricultural University , Peshawar , Pakistanb West Texas A&M University , Canyon Texas , USAAccepted author version posted online: 21 Jan 2014.Published online: 21 Jan 2014.
To cite this article: Journal of Plant Nutrition (2014): Cool Season C3-Grasses “Wheat, Rye, Barley, And Oats” Differ In Shoot:Root Ratio When Applied With Different NPK Sources, Journal of Plant Nutrition, DOI: 10.1080/01904167.2014.881877
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Cool Season C3-Grasses “Wheat, Rye, Barley, And Oats” Differ In Shoot: Root Ratio When
Applied With Different NPK Sources
Amanullah,1,2
B.A. Stewart,2 and Hidayat Ullah
1
1Department of Agronomy, Faculty of Crop Production Sciences, Khyber Pakhtunkhwa Agricultural
University, Peshawar-Pakistan
2West Texas A&M University, Canyon Texas, USA
Address correspondence to Amanullah, E-mail Author: [email protected]
ABSTRACT
Shoot: root (S:R) response in four winter C3-grasses (cereals) viz. wheat (Triticum aestivum L.), rye
(Secale cereale L.), barley (Hordeum vulgare L.) and oats (Avena sativa L.) was investigated under eight
different NPK sources (S1 = 20-20-20, S2= 20-27-5, S3 = 7-22-8, S4 = 10-10-10-20S, S5 = 11-15-11, S6 =
31-11-11, S7 = 24-8-16, and S8 = 19-6-12) in pot experiment at Dryland Agriculture Institute, West Texas
A&M University, Canyon, Texas, USA during winter 2009-10. The experiment was performed in
completely randomized design (CRD) with three repeats. The objective of this experiment was to
investigate whether the S:R of winter cereals differ or not when applied with different NPK sources.
Considerable variations in the shoot: root was noticed in the four grasses at different growth stages, i.e.,
30, 60 and 90 days after emergence (DAE) when applied with different NPK fertilizers sources. Wheat
had the highest S:R of 3.4 at 30 days after emergence (DAE), barley at 60 DAE (6.5), while oats at 90
DAE (3.9). Among the NPK sources, crops had the highest S:R of 3.6, 6.2 and 3.7 when applied with S3,
S2, and S6 at 30, 60 and 90 DAE, respectively. Shoot to root ratio showed positive relationship with
increase in shoot weight and negative relationship with increase in root weight. The NPK fertilizer S6 (31:
11: 11), an acid loving fertilizer had negative effects on the shoot and root development of cool season
cereals, but among these cereals under study, barley and oats roots were affected more than wheat and
rye. It was concluded from this present study, that the four cool season cereals responded differently in
terms of shoot: root to different NPK fertilizers at different growth stages.
Keywords: Triticum aestivum, Secale cereale, Hordeum vulgare, Avena sativa, NPK sources, and
shoot to root ratio
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INTRODUCTION
Straw retention and N application all improved organic C and N in soil, but the magnitude of
change depends on soil type and climatic conditions (Malhi et al., 2011). Adoption of better
management strategies such as continuous cropping, reduced tillage, improved fertilization,
application of organic amendments and crop rotations including perennial forage can increase the
amount of organic C and/or N stored in the soil (Malhi et al., 2008, 2009). The annual carbon (C)
inputs to soils from crop residues can be divided into two major sources: aboveground (i.e.,
straw, stubble and surface debris) and below-ground (i.e., root biomass left in the soil at harvest,
root turnover, exudates and secretions). One of several management practices proposed to
sequester atmospheric CO2 as soil organic weight is to expand the area of crops such as perennial
forages that increase the annual crop residue C inputs to soils (Bolinder et al., 2002).
The S:R of standing crops are commonly used to estimate the annual crop residue C
inputs to the soil from the root biomass left in the soil at harvest. However, root biomass has
often been neglected in field studies and estimates of S:R for many commonly grown forage
species are not available (Bolinder et al., 2002). Shoot-root relationship by weights gives an
estimate of root mass that remains in soil if shoot weight is known. In contrast to shoot, dry
weight partitioning in roots is high during the seedling stages of crop growth and steadily
declines throughout development (Evans and Wardlaw, 1976). Shoot-root ratios in different
crops increase as the plants advanced in age (Fageria, 1992) and environmental stresses increase
relative weights of roots compared to shoots (Eghball and Maranville, 1993). When plants are
nitrogen deficient, relatively more photosynthates is used by roots as they develop greater length
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to aid the plants in obtaining more N (Fageria et al., 2006). The mineral nutrients P and N
exerted pronounced influences on photosynthates and dry weight partitioning between shoots
and roots (Costa et al., 2002; Davidson, 1969). Under nitrogen (N) deprivation, translocation of
photoassimilates from shoots to roots increased because of increased sink strength of roots
compared to shoot sinks (Champiny and Talouizte, 1981). Root-shoot ratios of maize plants were
higher when grown with low soil N compared to adequate N (Eghball and Maranville, 1993).
Root development varies with stages of plant growth and development (Fageria et al., 2006), and
the most rapid development in maize roots was observed during the first eight weeks after
planting (Anderson, 1987). After silking, maize root length declines (Mengal and Barber, 1974)
indicating high C demand of grain, resulting in enhanced translocation of C and N to grain,
including some C and N that roots would normally obtain (Wiesler and Horst, 1993). Increase in
root weight and density increases when soil nutrients are concentrated have been reported by
Dunbabin et al. (2001) and Ma et al. (2007).
Studies on different NPK sources on the shoot-root ratio of cool season C3-cereals has not
been carried out so for. The objective of this study was to study whether different N-phosphorus
(P)- potassium (K) sources influence the shoot-root ratio in cool season cereals at different
growth stages or not?
MATERIALS AND METHODS
Shoot: root (shoot weight divided by root weight) of four cool season C3-grasses (cereals) viz.
wheat (Triticum aestivum L., cv. ‘TAM III’), rye (Secale cereale L., cv. ‘Elbon’), barley
(Hordeum vulgare L., cv. ‘P919’) and oats (Avena sativa L., cv. Walker) was investigated using
eight different NPK sources [S1 = 20-20-20 (Peter Professional by Scotts), S2= 20-27-5 (Starter
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Fertilizer by Scotts), S3 = 7-22-8 (Bedding Plant Food by FertiLoam), S4 = 10-10-10-20S (Shake
in Feed by Miracle Grow), S5 = 11-15-11 (Gardner’s Special by FertiLoam), S6 = 31-11-11 (Acid
Loving by FertiLoam), S7 = 24-8-16 (All Purpose Plant Food by Expert Gardner), and S8 = 19-6-
12 (Slow Release by Expert Gardner)]. Each NPK source was applied at the rate of 300 mg kg-1
of potting soil (miracle grow*) in pot experiment at Dryland Agriculture Institute, West Texas
A&M University, Canyon, Texas, USA during winter 2009-10. The fertilizer was mixed in the
potting soil and then the pots were filled. The experiment was performed in completely
randomized design (CRD) with three repeats. There were 32 pots (treatments) per repeats and a
total of 96 pots in the whole experiment. Twenty seeds of each crop was planted in each pot, and
after one week of emergence 15 plants were maintained per pot, and then five plants were
uprooted at 30, 60 and 90 days after emergence (DAE).
The root were washed with tap water, and the plants were then divided into three parts
i.e. roots, leaves and stems. The materials was put in paper bags and then put in an oven at 800C
for about 20-24 hours. The samples were weighing by electronic balance (Sartorius Basic,
BA2105) and the average data on dry weight of root, leaf, and stem per plant was worked out.
Shoot dry weight per plant was obtained by adding leaf dry weight with stem dry weight per
plant. The sum of the shoot and root dry weight was calculated as the total dry weight per plant.
Shoot dry weight per plant was divided by root dry weight per plant to get data on shoot: root
ratio (S:R).
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Characteristics of Miracle Grow
Miracle Grow is formulated from 50-60% sphagnum peat moss, coconut husk fibers (coir pith),
composted bark fines, pertile, wetting agent, and fertilizer. The nitrogen, phosphorus and
potassium sources have been coated to provide 0.10 % slow-release nitrogen (N), 0.10 % slow-
release phosphate (P2O5), and 0.10 % potash (K2O). The ACGIH threshold Limit Values (TLV)
for nuisance (inert) dust containing less than 1 % crystalline silica and no abestas are: 10 mg/m3
inhalable particulates and 3 mg m-3
respirable particulate. The bulk density (0.32 g cm-3
) and
porosity (88 %) for miracle grow was also calculated in the green house.
Statistical Analysis
Data were subjected to analysis of variance (ANNOVA) according to the methods described in
Steel and Torrie (1980) and treatment means were compared using the least significant
difference (LSD) at P ≤ 0.05.
RESULTS AND DISCUSSION
30 Days after Emergence
Shoot: root (S:R) in cool season cereals varied significantly (P ≤ 0.05) at 30 DAE (Table 1).
Wheat had the highest S:R (3.4), followed by rye (2.8), and oats had the lowest S:R (2.0) at first
cut. Although both wheat and barley produced similar shoot dry weight of 40.5 and 40.9 mg
plant-1
, respectively, but the highest root dry weight (15.8 mg plant-1
) of barley than wheat (12.1
mg plant-1
) resulted in the highest S:R in case of wheat than barley. In contrast, rye with the
lower shoot dry weight (25.4 mg plant-1
) than barley (40.9 mg plant-1
), but its lowest root dry
weight (9.1 mg plant-1
) resulted in the highest S:R than barley. The lowest shoot dry weight (18.5
mg plant-1
) of oats resulted in the lowest S:R than barley indicating positive relationship of shoot
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weight and S:R among cool season cereals. The S:R among cool season cereals varied
significantly (P ≤ 0.05) when applied with different NPK sources (Table 1). Crops had the
highest S:R (3.6) when applied with S3, and the lowest S:R (1.7) was produced when crops were
applied with S6. The highest S:R with application of S3 was due to the highest shoot weight (34.0
mg plant-1
) and lowest root weight (9.5 mg plant-1
). The lowest shoot dry weight (18.1 mg plant-
1) with application of S6 resulted in the lowest S:R in cool season cereals. Hamblin et al. (1990)
reported that in stressful environments, the allocation of resources to below ground growth may
be high which may reduce above ground growth.
When arranged across crops, wheat and barley had the higher S:R than rye and oats when
applied with S1, S3, S5 and S7 (Figure 1 and Table 1). Both wheat and barley had the higher shoot
and root dry weights plant-1
when applied with S1, S3, S5 and S7, and therefore S:R in both wheat
and barley increased significantly. Wheat and rye had more S:R than barley and oats when
applied with S4, S6 and S8. On one hand, the higher S:R in wheat with S4, S6 and S8 than barley
was due to the lower roots dry weight of wheat than barley; on the other hand, the higher S:R of
wheat than oats and rye was because of the higher shoot dry weight plant-1
of wheat. Similarly,
application of S2 resulted in the higher S:R in wheat than barley, rye and oats. Application of S2
resulted in the lower root dry weight in wheat (12.6 mg plant-1
) than barley (20.1 mg plant-1
) and
so the S:R in wheat increased than barley; but the higher S:R in wheat than rye and oats was
attributed to the higher shoot weight of wheat (37.4 mg plant-1
) than rye (23.1 mg plant-1
) and
oats (15.1 mg plant-1
). Sadras and Calderini (2009) reported strong relationship between root and
shoot growth with considerable interaction between the two.
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When arranged across NPK sources, wheat had the highest S:R when applied with S3 and
S8, and the lowest S:R in wheat was observed with S6 (Figure 1 and Table 1). Application of S3
and S8 had positive impacts on the shoot weight and negative impacts on the root weight and so
the S:R in wheat increased. The lowest S:R in wheat with S6 was because of the minimum shoot
weight produced by wheat (23.5 mg plant-1
). Rye had the highest S:R when applied with S3
because of the lower root weight (6.9 mg plant-1
) and the higher S:R when applied with S4 was
because of the higher shoot weight (34.3 mg plant-1
). The lowest S:R in rye with application of
S7 was attributed to the lower shoot weight (19.9 mg plant-1
) and higher root weight (10.1 mg
plant-1
) of rye. Barley had the highest S:R with S3 and S5, and the lowest S:R in barley was
observed with S6. Application of S3 had negative impacts on root weight of barley (11.0 mg plant-
1) and S5 had positive impacts on the shoot weight of barley (49.6 mg plant
-1) and so the S:R in
barley increased. The lowest S:R in barley with S6 was because of the minimum shoot weight
produced (25.1 mg plant-1
). Oats had the highest S:R when applied with S3 and S4, and the lowest
S:R in oats was observed with application of S6 and S7 each. Application of both S3 and S4 had
positive impacts on the shoot weight of oats (29.5 and 25.6 mg plant-1
, respectively) that
increased the S:R in oats. The lowest S:R in oats with application of S6 and S7 was because of the
minimum shoot weight produced by oats (7.3 and 11.8 mg plant-1
, respectively). Evans and
Wardlaw (1976) reported that shoot-root relationship by weights gives an estimate of root mass
that remains in soil if shoot weight is known. They also found that in contrast to shoot, dry
weight partitioning in roots is high during the seedling stages of crop growth and steadily
declines throughout development.
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60 Days after Emergence
The S:R among cool season cereals varied significantly (P ≤ 0.05) at 60 DAE (Table 2). Barley
had the highest S:R (6.51), followed by rye (5.74); while wheat had the lowest S:R (4.08). At 60
DAE, wheat had the highest root dry weight (249.7 mg plant-1
) that was the main reason to
reduced the S:R in wheat to minimum as compared to other cereals. Although barley ranked
second in terms of root dry weight (147.0 mg plant-1
) but its highest shoot dry weight (1004.2 mg
plant-1
) at 60 DAE put barley to the top in terms of S:R than other crops. The S:R among cool
season cereals varied significantly (P ≤ 0.05) when applied with different NPK sources (Table
2). Crops had the highest S:R (6.18) when applied with S2, being at far with S1 (6.15), S3 (5.51),
S5 (6.04) and S8 (5.85); while the lowest S:R(4.36) was obtained when crops were applied with
S6. The highest shoot dry weights of 1158.0 and 1031.5 mg plant-1
recorded for S1 and S2,
respectively was the possible cause of the highest S:R for both NPK sources. On the other hand,
the lowest shoot dry weight (122.1 mg plant-1
) and the lowest root dry weight (24.9 mg plant-1
)
was noted with S6 that resulted in the lowest S:R in the crops. Eghball and Maranville (1993)
reported that environmental stresses increase relative weights of roots compared to shoots.
When arranged across crops, barley and oats had the higher S:R than wheat and rye when
applied with S1 and S4 (Figure 2 and Table 2). The higher S:R in barley than wheat and rye was
attributed to the higher shoot weight of barley when applied with S1 (1715.3 mg plant-1
) and S4
(906.6 mg plant-1
). The higher S:R in oats than wheat and rye was attributed to the lower root
weight of oats when applied with S1 (117.2 mg plant-1
) and higher shoot weight of oats when
applied with S4 (1039.2 mg plant-1
). Rye and barley had higher S:R than wheat and oats when
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applied with S2 and S3. The lower S:R in wheat than rye and barley was attributed to the highest
root weight of wheat when applied with S2 (357.2 mg plant-1
) and S3 (308.3 mg plant-1
). But the
lower S:R in oats than rye and barley was attributed to the lowest shoot weight of oats when
applied with S2 (349.0 mg plant-1
) and highest root weight of oats when applied with S3 (177.3
mg plant-1
). Application of S5 and S8 resulted in the higher S:R in barley and oats than wheat and
rye. When applied with S5 and S8, barley produced higher shoot weight than wheat and rye and
so the S:R in barley increased. Because the higher the shoot weight the higher will be the S:R.
But application of S5 and S8, oats produced lower root weight than wheat and rye and so the S:R
in oats increased. Because the lower the root weight the higher will be the S:R in crop plants.
When application of S6 resulted in the higher S:R in wheat and rye than barley and oats, while
application of S7 resulted in the higher S:R in wheat and barley than rye and oats. When applied
with S6 and S7, wheat produced higher shoot and root weights than all other cereals and so the
S:R in wheat was higher. Costa et al. (2002) and Davidson (1969), the mineral nutrients P and N
exerted pronounced influences on photosynthates and dry weight partitioning between shoots
and roots.
When arranged across NPK sources, wheat had the highest S:R when applied with S6 and
S7, and the lowest S:R in wheat was observed with S4 (Figure 2 and Table 2). Application of S6
had negative influence on the root (41.8 mg plant-1
) as well as shoot weight (259.9 mg plant-1
) of
wheat and so higher S:R was calculated. Application of S7 had positive influence on shoot
(1070.7 mg plant-1
) but negative impacts on the root weight (209.3 mg plant-1
) that also resulted
in the higher S:R in wheat. The lowest S:R in wheat with S4 was because of the minimum shoot
weight (674.4 mg plant-1
) and higher root weight (262.2 mg plant-1
) in wheat. Rye had the
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highest S:R with S2 and S5, and the lowest S:R in rye was observed with S4. Rye produced
maximum shoot weight (1129.0 mg plant-1
) when applied with S2 that increased the S:R in rye.
Although application of S5 had lower shoot weight (800.1 mg plant-1
) in rye than S1 (934.2 mg
plant-1
), but the lower root weight (127.3 mg plant-1
) with application of S5 increased S:R in rye
than S1 having higher root weight (167.0 mg plant-1
). Barley had the highest S:R with S1 and S2,
and the lowest S:R in barley was observed with S6. Barley ranked first in terms of root (208.2 mg
plant-1
) and shoot dry weight (1715.3 mg plant-1
) when applied with S1 that resulted in the higher
S:R in barley. Barley ranked second in terms of shoot dry weight (1323.3 mg plant-1
) when
applied with S2 but the lower root weight (152.7 mg plant-1
) than some other treatments resulted
in the higher S:R in barley. Oats had the highest S:R when applied with S1 and S4, and the lowest
S:R in oats was observed with application of S6. Oats ranked first in terms of shoot dry weight
(1039.2 mg plant-1
) when applied with S4 that resulted in the higher S:R in oats. Although
application of S1 increased shoot dry weight (840.7 mg plant-1
) but the lower root weight (117.2
mg plant-1
) of oats than some other treatments increased S:R in oats. Fageria (1992) reported that
increase in shoot-root ratios of common bean, rice, wheat, and cowpea as plants advanced in age,
and the decrease in shoot-root ratios with time indicating roots have preferential utilization of
photosynthates under the existing plant growth conditions.
90 Days after Emergence
The S:R among cool season cereals varied significantly (P ≤ 0.05) at 90 DAE (Table 3). Oats
had the highest S:R 3.89), followed by barley (3.22); while wheat had the lowest S:R (1.78).
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Wheat had the highest root dry weight (1287 mg plant-1
) that resulted in the lowest S:R in wheat,
while oats had the lowest root dry weight (447 mg plant-1
) that resulted in the highest S:R in oats
at 90 DAE. Although barley had the highest shoot dry weight (2571 mg plant-1
) but its S:R
ranked second to oats, because of the lowest root dry weight per plant of oats. Barley S:R was
greater than wheat, because of the highest root dry weight per plant of wheat at 90 DAE. The
highest shoot dry weight of barley (2571 mg plant-1
) than wheat (1945 mg plant-1
) was another
reason that increased S:R of barley than wheat. The S:R among cool season cereals varied
significantly (P ≤ 0.05) when applied with different NPK sources (Table 3). Crops had the
highest S:R (3.69) when applied with S6, being at far with S1 (3.30) and S8 (3.19); while the
lowest S:R (2.62) was obtained when crops were applied with S3. The lowest root dry weight
(248 mg plant-1
) produced by the crops with application of S6 resulted in the higher S:R at 90
DAE. Crops had the highest shoot dry weight (2696 mg plant-1
) as well as root dry weight (1129
mg plant-1
) when applied with S2, and so the S:R was reduced because of the highest root dry
weight per plant as compared to S6, S1 and S8. Lucas et al. (2000) reported that wheat and other
cereals due to the increasing N supply enhanced both shoot and root growth, but usually shoot
growth more than root growth, leading to increased S:R on dry weight basis when N supply was
increased.
When arranged across crops, barley and oats had the higher S:R than wheat and rye when
applied with S1, S3, S4, S5, S7 and S8 (Figure 3 and Table 3). The higher S:R in barley and oats
when applied with S1, S3, S4, S5, and S8 was attributed to the higher shoot weight of barley and
oats than wheat and rye. Application of S7 produced higher shoot weight in wheat (2879 mg
plant-1
) than barley (2140 mg plant-1
) and oats (499 mg plant-1
); but the lower root dry weight of
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both barley (722 mg plant-1
) and oats (163 mg plant-1
) was the major cause that resulted in the
higher S:R in barley and oats than wheat. Application of S2 resulted in the higher S:R in rye and
oats than wheat and barley, while application of S6 resulted in the higher S:R in rye and barley
than wheat and oats. When applied with S2, both rye and oats produced lower shoot weights
than wheat and barley, but the lower root weight of oats (358 mg plant-1
) and rye (716 mg plant-
1) than wheat (1829 mg plant
-1) and barley (1613 mg plant
-1) resulted in the higher S:R in rye and
oats than wheat and barley. Application of S6 produced lower shoot weight in rye (932 mg plant-
1) and barley (817 mg plant
-1) as compared to wheat (1603 mg plant
-1); but the lower root
weights of both rye (248 mg plant-1
) and barley (185 mg plant-1
) was the main cause of higher
S:R than wheat which produced higher root weight (469 mg plant-1
) when applied with S6. The
higher S:R in oats was due to the too negative influence of S6 (an acid loving fertilizer) on the
roots weight of oats (92 mg plant-1
), although oats also ranked in the bottom in terms of shoot
weight (164 mg plant-1
) when applied with S6. Costa et al. (2002) suggested that the mineral
nutrients P and N exerted pronounced influences on photosynthates and dry weight partitioning
between shoots and roots.
When arranged across NPK sources, wheat had the highest S:R when applied with S4 and
S6, and the lowest S:R in wheat was obtained with application of S5 (Figure 3 and Table 3). The
highest S:R in wheat with application of S4 and S6 was attributed to the lowest wheat roots
weight (494 and 469 mg plant-1,
respectively). The lowest S:R (0.93) of wheat when applied with
S5 was because of lower shoot weight (1490 mg plant-1
) and higher roots weight (1605 mg plant-
1). Rye had the highest S:R with S2 and S6, and the lowest S:R in rye was observed with S3. The
highest S:R in rye with application of S2 was because of the maximum shoot weight (2404 mg
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plant-1
), but the highest S:R with application of S6 was because of the minimum roots weight
(248 mg plant-1
). The lowest S:R in rye was observed with S3 because of the lower shoot weight
(1285 mg plant-1
) and higher root weight (553 mg plant-1
) of rye. Barley had the highest S:R with
S6 and S8, and the lowest S:R in barley was observed with S4. The highest S:R in barley with S6
was because of the minimum root weight (185 mg plant-1
), but the highest S:R with S8 was
because of the higher shoot weight (3003 mg plant-1
) as compared to S1, S2, S3 and S5. Oats had
the highest S:R when applied with S1 and S8, and the lowest S:R in oats was observed with
application of S6. The highest S:R in oats with S1 and S8 was because of the highest shoot weight
(2683 and 2760 mg plant-1,
respectively). The lowest S:R in oats with application of S6 was
attributed to both the lowest shoot and root weights (164 and 92 mg plant-1,
respectively).
The S:R in the cool season cereal increased with passage of time from 30 to 60 DAE; but
further advancement in age up to 90 DAE decreased the S:R in crops. Evans and Wardlaw
(1976) reported that dry weight partitioning in roots is high during the seedling stages of crop
growth and steadily declines throughout development. Although, of some NPK sources increased
both shoot and root weights. But the increase in shoot was more than roots that resulted in the
higher S:R in the crops. Earlier research (Robinson et al., 1994; Marschner, 1995; and Lucas et
al., 2000) reported that wheat and other cereals due to the increasing N supply enhanced both
shoot and root growth, but usually shoot growth more than root growth, leading to increased S:R
on dry weight basis when N supply was increased. According to Costa et al., (2002) and
Davidson (1969), the mineral nutrients P and N exerted pronounced influences on
photosynthates and dry weight partitioning between shoots and roots. Adoption of better
management strategies such as continuous cropping, reduced tillage, improved fertilization,
application of organic amendments and crop rotations including perennial forage can increase the
amount of organic C and/or N stored in the soil (Malhi et al. 2008, 2009). Izaurralde et al. (2001)
observed an increase or no reduction of C on a continuous wheat-oats-barley-hay-hay rotation
after 50 years at Breton.
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CONCLUSIONS
The shoot-root relationship (by weights) gives an estimate of the root mass that remains in soil if
shoot weight is known. Shoot to root ratio showed positive relationship with increase in shoot
weight and negative relationship with increase in root weight. In some cases, too little root
weight increased the shoot to root ratio to maximum even the plants having the lowest shoot
weight. The NPK fertilizer S6 (31: 11: 11), an acid loving fertilizer had negative effect on the
shoot and root development of cool season cereals, but among these cereals under study, barley
and oats roots were affected more than wheat and rye. Wheat and rye showed tolerance to this
acidic fertilizer as compared to barley and oats. Moreover, this fertilizer because of its higher N
content (31 %) was also responsible for the reduction in root weight. In the present study, the
four cool season cereals responded differently in terms of shoot: root to different NPK fertilizers
at different growth stages. An important result of the present work was that biomass partitioning
between shoots and roots among the crops at various growth stages cannot be supposed to be
constant. Our results also indicated that different crops allocate variable proportion of biomass to
their roots at different growth stages.
ACKNOWLEDGMENTS
I am highly thankful to Dr. B.A. Stewart, Director and Distinguished Professor of Dryland
Agriculture Institute, West Texas A&M University Canyon, Texas USA for providing me the
opportunity to complete this research project. Many thanks are extended to Prof. Dr. Paigham
Shah, Agricultural University Peshawar for the statistical analysis of the data. This study was the
part of my post doctorate research financed by the Higher Education Commission of Pakistan,
Islamabad.
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Table 1. Shoot: Root response of cool season cereals to different NPK sources at 30 days
after emergence.
NPK Sources N-P2O5-K2O Wheat Rye Barley Oats Mean
S1 20-20-20 3.5 2.9 3.2 1.5 2.8
S2 20-27-5 3.0 2.2 2.2 1.8 2.3
S3 7-22-8 4.0 3.6 3.4 3.2 3.6
S4 10-10-10-
20(S) 3.2 3.6 2.6 2.5 3.0
S5 11-15-11 3.7 3.2 3.3 2.2 3.1
S6 31-11-11 1.9 2.1 1.5 1.4 1.7
S7 24-8-16 3.2 2.0 2.3 1.4 2.2
S8 19-6-12 4.7 3.3 2.6 2.0 3.2
Mean 3.4 2.8 2.6 2.0 2.7
LSD0.05
Crops 0.2
NPK Sources 0.3
Interaction 0.6
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Table 2. Shoot: Root response of cool season cereals to different NPK sources at 60 days
after emergence.
NPK Sources N-P2O5-K2O Wheat Rye Barley Oats Mean
S1 20-20-20 3.30 5.62 8.23 7.44 6.15
S2 20-27-5 3.70 7.13 8.67 5.21 6.18
S3 7-22-8 3.16 6.04 7.51 5.33 5.51
S4 10-10-10-
20(S) 2.61 4.82 4.59 7.62 4.91
S5 11-15-11 3.91 6.32 7.48 6.45 6.04
S6 31-11-11 6.99 5.32 2.59 2.56 4.36
S7 24-8-16 5.17 4.95 5.77 3.71 4.90
S8 19-6-12 3.82 5.75 7.21 6.60 5.85
Mean 4.08 5.74 6.51 5.62 5.49
LSD0.05
Crops 0.63
NPK Sources 0.90
Interaction 1.79
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Table 3. Shoot: Root response of cool season cereals to different NPK sources at 90 days
after emergence.
NPK Sources N-P2O5-K2O Wheat Rye Barley Oats Mean
S1 20-20-20 1.53 2.70 3.14 5.81 3.30
S2 20-27-5 1.51 3.36 2.59 4.66 3.03
S3 7-22-8 1.22 2.44 3.16 3.67 2.62
S4 10-10-10-
20(S) 1.96 2.64 2.33 3.94 2.72
S5 11-15-11 0.93 2.51 2.89 3.22 2.38
S6 31-11-11 3.91 4.02 5.09 1.76 3.69
S7 24-8-16 1.86 2.88 2.95 3.07 2.69
S8 19-6-12 1.36 2.82 3.60 5.00 3.19
Mean 1.78 2.92 3.22 3.89 2.95
LSD0.05
Crops 0.39
NPK Sources 0.55
Interaction 1.10
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Figure 1. Interactive effecs of NPK sources into grasses on the root: shoot at 30 days after
emergence.
Figure 2. Interactive effecs of NPK sources into grasses on the root: shoot at 60 days after
emergence.
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Figure 3. Interactive effecs of NPK sources into grasses on the root: shoot at 90 days after
emergence.
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