The 11th International Conference of Agronomy Sciences

The 11th Conference of Agronomy, Agron. Dept., Fac. Agric., Assiut Univ., Nov. 15-16, 2005

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GENETIC VARIABILITY AND HERITABILITY OF ALFALFA (MEDICAGO SATIVA L.) SEED YIELD AND ITS COMPONENTS.

Magdy M. Mohamed1,3 M. El-Nahrawy1 Z. Staszewski2 & A. Rammah1

1 Forage Crops Research Department, Field Crops Research Institute, ARC, Giza, Egypt.

2 Plant Breeding and Acclimatization Institute-IHAR, Radzików, Poland. 3 Author for correspondence; e-mail: [email protected].

ABSTRACT

A better understanding of the inheritance of new genes and its influence on the seed yield traits is necessary to develop alfalfa populations with the genetic capacity for high seed yield. Therefore, the objective of the present research was to identify the inheritance mode of seed yield and its components. The present study was conducted at Institute of Plant Breeding and Acclimatization, located in Radzików, Warsaw, Poland, from April, 1999 to July, 2003. • Both δ2A and δ2D were responsible for the expression of flowering date and seed

yield at BC1F2-generation level, shoots number plant-1 at BC2F2-generation level, flowering date, number of shoots and racemes per plant as well as seeds number pod-1 across two-generations. The presence of both additive and dominance effect for these traits led to moderate estimates of narrow-sense heritability.

• Because, the proportional contribution of male variance was larger than male vs. female interaction variance for the raceme traits in all evaluated generations, the additive variance contributed most of the genetic variance for these components. The lack of dominance effects suggests that raceme traits behave additively. Consequently, selection for raceme characters can be performed using breeding methods designed to exploit additive genetic variance.

• The negative value of narrow-sense heritability observed in BC2F2-generation for number of pods raceme-1 reflected absence of genetic variance in relation to the examined trait; where, the effect of males, females and their interactions was non-significant. The other reason for negative heritability is that highly adapted parents produced weakly adapted progeny, because, the environment was completely different in the two generations. High estimates of heritability were obtained for some seed yield components indicating that, the response to selection with any breeding program could be expected. In general, the broad sense-heritability was moderate to high.

• The raceme traits seem to be a reasonable breeding goal for improving seed yield in alfalfa. These traits showed high narrow-and broad-sense heritability, in addition, they were strongly influenced by the experimental populations carrying the long raceme peduncle-type.

INTRODUCTION

Alfalfa or lucerne (Medicago sativa L.), called “The Queen of the Forages” is one of the most important forage crops in terms of global total area, economic value and energy efficiency. Because alfalfa can fix nitrogen and synthesize protein, it is

very useful to farmers, who have grow alfalfa as protein-rich fodder for horses, cows, goats, sheep, pigs and chickens for at least 3300 years. Therefore, this crop plays a significant economic role in the market of animal feed (i.e., hay, dehydrated forage, pellets and silage

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products). Cultivated lucerne is an open pollinated species characterized by tetrasomic inheritance and multiple allelism and by pronounced inbreeding depression (Busbice and Wilsie, 1966). Although, seed yield has little agronomic importance in alfalfa varieties, it is critical in their marketing. So, seed setting is an important factor for the commercial development of forage varieties. However, the increase in seed yield potential during the last three decades has been imperceptible and little genetic progress has been achieved (Huyghe et al., 1999 and Falcinelli, 2000), since, this yield is not taken into account in the first cycles of selection. In spite of that, a low seed / ovule ratio is a general characteristic of outcrossing species (Seavey and Carter, 1996), lucerne varieties must be good seed producers, because low seed yield does not ensure adequate supplies of seed at reasonable prices (Lorenzetti, 1981). Yet in ranking lucerne varieties, seed yield has never constituted an important criterion and breeders have not devoted much work to improve seed yield in this species (Boçsa and Buglos, 1983). Also, Veronesi et al. (1986) reported that, the responses obtained with selection for seed yield were quite remarkable. Because direct selection for seed yield results in little progress (Bulletin FNAMS, France, 1988), it seems necessary to change the plant and flower morphology to obtain progress in seed yield potential of lucerne (Staszewski, 1995). Bolaños-Aguilar et al. (2001) reported that little information were available in alfalfa on the inheritance of seed yield itself and seed yield components, especially, those assessed at the inflorescence level. In addition, genetic increases in seed yield of alfalfa are less than those for most grain crops and the lower rate of gain in alfalfa yield can be attributed to greater emphasis on pest resistance vs. yield, the perennial nature of

the crop and the complex genetics of autotetraploids. The genetic contribution to seed yield has increased by only about 3% over an 80-yr period from 1898 to 1985 (Holland and Bingham, 1994) and most of the genetic improvement from 1979 to 1985 occurred without a significant reduction in genetic load (deleterious alleles). Breeding methods used to develop alfalfa cultivars usually focus on inter-mating a number of selected genotypes in all combinations (i.e., synthetics), rather than creating inbred lines which could be used for the production of hybrids (Barcaccia, 1994). The selection of superior individuals is usually based on a visible phenotype, for example plant vigor or on measurable traits such as raceme traits. However, the efficiency of this selection may be reduced by environmental effects on the measured character and by the complex inheritance of multigenic traits. Therefore, the objective of this study was to identify the inheritance mode of seed yield and its components under field environment.

MATERIALS AND METHODS The present study was carried out at Institute of Plant Breeding and Acclimatization, located in Radzików, Warsaw (Radzików lays near the geographical center of Europe: 52o13'N, 20o28'E), Poland, from April, 1999 to July, 2003.

Plant material development and mating design: In a greenhouse, hand pollinations were made with a hand emasculation and pollen was transferred by black photo film-paper as a boat shape among two non-recurrent parental plants {br.2fr/1x72/11: brtf-type (branched raceme and top flowering-type) and BC1F2-102: lptf-type (long raceme peduncle and top flowering-type)} and three recurrent parental plants (Giza-1, Ismailia-1, and Sewa) in a factorial mating design according to a North Carolina


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Designs, Model-II (NCD-II) as described by Comstock and Robinson (1948 and 1952) and defined in Fig. (1). In this design (NCD-II), the F2-populations are produced by crossing two parents and / or back crossing randomly selected F2-individuals (used as males) to each of recurrent parents (used as females). Female flowers (recurrent parents flowers) were emasculated by removing the standard petals, tripping the florets and removing anthers and pollen immediately. Pollen was collected from the male parents (non-recurrent parents) on the end of a clean black photo film-paper and applied to the stigma of the female flowers to be crossed. Afterwards, the crossed-racemes were tagged for identification.

Advanced-generations seed yield and seed yield components: In May, 2002, advanced generations (BC1F2 and BC2F2)-plants derived from the anterior crosses and their parents (P1, P2) were established in the field experiment (clear brown soil, clay-silt texture and pH 7.20) at Institute of Plant Breeding and Acclimatization Farm, Radzików, Warsaw, Poland. The experiment was planted in a randomized complete block design with four replications. A block consisted of: two non-recurrent parental plants {br.2fr/1x72/11 (brtf-type) and BC1F2-102 (lptf-type)} and three recurrent parental plants (Giza-1, Ismailia-1 and Sewa) and their BC1F2 and BC2F2-generations with double-row plots of 30-plants {plot = 2-rows; row length = 4.50 m; 15-plants / row; 30 cm between plants and 60 cm between rows}. The pollination among plants was acquired by native pollinators {Honey bees (Apis mellifera L.); Bumble bees (Bombus terrestris L. and Bombus hortorum L.) and Leaf cutter bees (Megachile spp.)},so, not to be a limiting factor. The plots were never clipped between cultivation until harvest of seeds. Pest control practices were in accordance with those recommended for Institute of

Plant Breeding and Acclimatization Farm. The plants-watered were depended on the rain, so, no irrigation was provided and, also, no insecticide was applied during the experiment.

Seed yield and its components were evaluated on a plant and plot basis, however, prior to harvest, four traits were taken as follows:

• Flowering date (days from planting) was recorded on each plot when about 50% of the stems-plot plants had one open flowering inflorescence.

• Plant height (cm) was obtained from measurement of long main stem at maturity.

• Number of shoots / plant and number of inflorescences / plant were counted.

Elsewhere, the remaining traits were measured at the lab as follows:

• Twenty random-inflorescences from plot-plants were sampled, number of pods / inflorescence was counted and raceme length was measured (cm).

• Number of flowers / raceme was determined by counting attachment sites on the racemes

• Twenty random-pods from these inflorescences were collected, bulked and threshed in order to count the seed number per pod.

• The seeds of the remaining inflorescences were cleaned, sieved, weighed and combined with the seed weight of 20-random inflorescences subsamples to record seed weight / plant.

• Seed index was determined by 1000-seeds weight.

• Whole plots were harvested and weighed (kg / plot) in the field, then, occasional sub-samples (about 0.500 kg) were taken.

• After that, harvested samples were oven dried at 80 oC for 72 h. and re-weighed to determine dry matter ratio.

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• Dry matter weight or aboveground phytomass (kg) was calculated on the basis of the dry matter ratio determined from the sub-samples {Dry matter weight (kg) = Plot fresh weight (kg) x Dry matter ratio}.

• Furthermore, the seeds / plots were air dried, cleaned, sieved and seed yield of each plot (gm) was recorded. Based on seed yield / plot and number of plants / plot, the seed yield / plant (gm) was calculated.

• Harvest index was calculated as a ratio of seed yield to total aboveground phytomass at harvest:

{Harvest index = seed yield / total aboveground phytomass}. Analyses of variance and genetic interpretation estimates in North Carolina Designs, Model-II (NCD-II) for seed yield and its components in alfalfa:

Quantitative traits analyses: Statistical analyses for seed yield and its components in advanced alfalfa-generations were performed using

COSTAT-program (Version 3.03, CoHort software, Berkeley, CA.) and the means were separated using Fisher’s LSD when significant occurred. Taking into account that, the analysis of variance was performed for BC1F2 and BC2F2, separately, and across two-generations. To reduce the experiment-wise error, we used a maximum “P” value of 0.01 to declare a significant association. The statistical model in this design (NCD-II) as follows:

Yijk = M + mi + fj + (m x f)ij + eijk Where: Yijk : observed trait. M : general mean. mi : male effect. fj : female effect. (m x f)ij : interaction effect. eijk :error associated with each observation.

According to this model, the

analysis of variance for males x females in North Carolina Designs-II (NCD-II) was acquainted in Table (1).

Table (1): ANOVA-Analysis of variance for males x females in NCD-II. S. O. V. d. f. M. S. Expected mean squares Males m-1 MSm δ2e + r δ2mf + frδ2m Females f-1 MSf δ2e + r δ2mf + mrδ2f Males x Females (m-1) (f-1) MSmf δ2e + r δ2mf Error mf (n-1) MSe δ2e

Further partitioning of sum squares of genotypes: For testing the significance of the crosses and parents individually, it is possible to partition the

sum squares of treatments into various components like parents, crosses and parents vs. crosses as given in Table (2).


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Table (2): Pooled data on males x females in two-way table. Males Females Total

(1) Giza-1 (2) Ismailia-1 (3) Sewa (1) brtf-type X1.1 X1.2 X1.3 m1

(2) lptf-type X2.1 X2.2 X2.3 m2 Total f1 f2 f3 G. T.

The sum squares of genotypes being:

)(....22

alloverFCr

PCgenotypestodueSS ijij −∑∑+∑∑

=

With 10 degrees of freedom {No. of parents (5) + No. of crosses (6), being 11}. Where: Cij: the observation for i x j cross. Pij: the observation for i and j parents.

r: number of replications.

Because, ),(....2

crossesFCrCcrossestodueSS ij −

∑∑= with 5 d.f.

and, ),(....2

parentsFCrPparentstodueSS ij −

∑∑= with 4 d.f.

Therefore, S. S. due to parents vs. crosses = S. S. (genotypes) - S. S. (crosses) - S. S. (parents), with 10 – 5 – 4 = 1 d.f. Or: S. S. due to parents vs. crosses = C. F. (crosses) + S. S. (parents) - C. F. (overall).

Males x females analysis: From the pooled data on males x females in two-way table (Table 2), we can estimating the sum of squares for males, females and males x females-interaction as follow:

)(....2

crossesFCrfmmalesdueSS −

∑∑=

)(....2

crossesFCrm

ffemalestodueSS −∑∑

=

S. S. due to males x females = S. S. (crosses) - S. S. (males) - S. S. (females).

Estimation of genetic components: Additive, dominance and general and specific combining ability variances based on an autotetraploid model were calculated according to Wricke and Weber (1986) with slight modification to adapt it to North Carolina Designs, Model-II: δ2A = 2 (δ2

m + δ2f) - 2/3(δ2

mf) δ2A = 4 δ2gca - 2/3 δ2sca δ2D = 6 δ2

mf = 6 δ2sca where: δ2A : additive variance. δ2D : dominance variance. δ2gca: GCA variance.

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δ2sca: SCA variance.

Relative importance (R. I.) of additive vs. non-additive effects:

The total genetic variance among single-cross progeny is equal to twice the general combining ability (GCA) component of variance (δ2g x 2) plus the specific combining ability (SCA)

component (δ2s). Based on this ratio, it would seem that, the R.I. of GCA and SCA in determining progeny performance should be assessed (Baker, 1978) by estimating the components of variance and expressing them in this ratio:

sggIR 22

2

22..

δδδ

+=

Accordingly, Rooney et al. (1997) this ratio was modified to fit expectations for autotetraploids as follows:

DAAIR 22

2

..δδ

δ+

=

where:

δ2A: variance of the additive effect.

δ2D: variance of the non-additive effect.

Proportional contribution of males, females and their interactions to total variance :

)(..100)(..

crossesSSxmSSmalesofonContributi =

)(..100)(..

crossesSSxfSSfemalesofonContributi =

)(..100)(..

crossesSSxmfSSfemalesxmalesofonContributi =

Estimation of Heritabilities:

The narrow-sense heritability (as additive variance proportion of the total variance observed) based on an autotetraploid model was estimated

according to Wricke and Weber (1986):

h2NS =

eDA

DA222

22

31

δδδ

δδ

++

+

While, the broad-sense heritability

(h2BS) is defined as the ratio of genotypic

to phenotypic variance: h2BS

=)()(

2

2

PhVGV

PhG

=δδ

RESULTS AND DISCUSSION

Significant differences were found among genotypes for most evaluated characters, except for plant height and aboveground phytomass per plot of all generations, number of racemes per plant in BC1F2- and BC2F2-generations, number of shoots per plant at BC1F2-generation level and flowering date at BC2F2-generation level (data not shown). Thus, these traits were not considered for the subsequent analysis. The large genotype effect under field conditions was most likely due to the different origins of genotypes included in the present study and its crosses performances. Where, our materials involved two different sub-species; Medicago sativa L. ssp. sativa and Medicago sativa L. ssp. falcata. When the variation due to genotypes was subdivided into parents, crosses and parents vs. crosses effects, the parents variance was significant for most traits, bating of, flowering date, plant height, number of shoots and racemes per plant, aboveground phytomass per plot for all examined generations as well as seed index at BC1F2


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–and BC2F2-generations level (data not shown). Crosses variance was significant for flowering date, shoots number per plant, raceme length and flowers number per raceme for all generations. In addition, it was significant for racemes number per plant (BC2F2 –and across two-generations), number of pods per raceme and seeds per pod, seed index, seed yield per plant and hectare and harvest index (BC1F2-generation) and seed yield per plot (across two-generations). Whilst, variance due to parents vs. crosses interaction was significant, only, for plant height, raceme length and flowers number per raceme at all generations. Furthermore, when the crosses effect was partitioned into its variance components (males, females and males x females), the three components were significant at BC1F2-generation level for flowering date, seeds number / pod and seed yield / plot. To bear resemblance to the males variance, it was significant in all evaluated generations for raceme length, flowers number / raceme, seeds number / pod and seed index. The females variance was significant for number of shoots and racemes per plant in BC2F2 –and across two-generations and flowering date at across two-generation level. Estimates of additive (δ2A) and dominance (δ2D) variances and relative importance (R. I.) are summarized in Table (3). Both δ2A and δ2D were responsible for the expression of flowering date, and seed yield per plant and plot at BC1F2-generation level, shoots number / plant at BC2F2-generation level, flowering date, number of shoots and racemes per plant as well as seeds number / pod across two-generation. The presence of both additive and dominance effects for these traits led to moderate estimates of narrow-sense heritability which ranged from 0.31 for seed yield per plot at BC1F2-generation level to 0.60 for number of seeds per pod across the two-generations. In case of seed

yield at BC1F2-generation level and number of pods per raceme across two-generations, the narrow-sense heritability values were low, while, the broad-sense heritability was higher. This result suggested that almost low variation was due to additive genetic components and the most variability was controlled by interactions of a digenic, trigenic and quadrigenic nature and heterozygosity, because of, the autotetraploid nature of the species. Because, the proportional contribution of males variance was larger than males vs. females interaction variance for the raceme traits i.e. raceme length and number of flowers and pods per raceme in all evaluated generations (Table 4), the additive variance contributed to most of the genetic variance for these components (Table 3). The lack of dominance effects suggests that raceme traits behave additively. This hypothesis indicated that raceme traits are most likely polygenic and highly additive. Consequently, this result suggest that effective selection for raceme characters can be performed using breeding methods designed to exploit additive genetic variance. Exceptionally, number of pods per raceme in BC2F2-generation and across two-generations, high additive variance led to high estimates of the narrow-sense heritability (Table 5) which indicated that, these traits would be more efficient selection criteria for seed yield as well as seed index than other traits. The narrow-sense heritability values were moderate to high, therefore, account for an almost considerable amount of phenotypic variation for seed yield and all seed yield components, except for harvest index trait in BC1F2-generation. Consequently, the expected genetic gains from selection would be high. These findings complement the results draw from genetic components studies. Likewise, broad-sense heritability for all traits was moderate (0.53-0.65) to high (0.65-0.85) as shown in Table (5). This reflects high

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genetic and low error variances (data not shown). Conversely, Bolaños-Aguilar et al. (1999 and 2000) reported that, the broad-sense heritability for all seed yield components in alfalfa were relatively low because of large residual variance.

Also, the variation due to genotype was subdivided into general (δ2gca) and specific (δ2sca) combining ability variances (Table 5). The results showed that, the δ2gca was the main source of genotypic variance for seed yield and all seed yield components at BC2F2-generation level. The prevalence of δ2gca could be due to the choice of male parent plants, thus, leading to linkage disequilibrium, even, if none of female parent plants were especially selected for seed yield. The same conclusion was outlined by Bolaños-Aguilar et al. (2001) who reported that GCA was the main source of genotypic variation and was highly significant for all the characters influencing seed yield, except for seed weight / pod. In contrast, the δ2sca was the predominant factor affecting, only, harvest index character in BC1F2-generation. Ever so, the combining ability studies help plant breeder in identifying parents with high

GCA and cross combinations

showing high SCA. Accordingly, the male parent lptf-type and female parent Giza-1 had significantly positive general

combining ability (GCA) variances for seed yield and most of its components. In contrast, the male parent brtf-type had negative GCA values for most traits. Differences in the specific combining ability (SCA) variances of single crosses were pronounced for seed yield and its components. So, the results indicated that genotypes with the lowest GCA effects don’t produce crosses with the lowest SCA effects and genotypes with the highest GCA effects don’t produce crosses with the highest SCA. Therefore, we can conclude that single crosses abided a high SCA didn’t necessarily have parents with a high GCA and vice versa. This result would be expected, because, there are appreciable amounts of additive and dominance genetic components controlling the expression of these traits such as flowering date, raceme length, number of flowers and pods per raceme, number of seeds per pod, seed index as well as seed yield. Increased seed yield in Sewa x lptf-type cross at BC1F2-generation level, may be due to the merger of most favorable alleles rather than the temporary effect of heterozygosity. Under these circumstances, positive and significant SCA effect value would be expected as selection would fix the additive genetic components of GCA effect for characters influenced by selection.


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Table (3): Estimates of additive (δ2A) and dominance (δ2D) variances and relative importance (R. I.) in the factorial crosses for seed yield

and seed yield components of alfalfa in BC1F2 and BC2F2-generations and across two-generations under field environmental conditions.

Traits BC1F2-generation BC2F2-generation Across two-generations

δ2A δ2D R. I. δ2A δ2D R. I. δ2A δ2D R. I.

1. Flowering date (days)§ 32.3820 90.8748 0.26 --- --- --- 20.8381 12.3306 0.63

2. Plant height (cm)§ --- --- --- --- --- --- --- --- ---

3. No. of shoots / plant§ --- --- --- 6.6781 0.6456 0.91 4.0443 2.6952 0.60

4. No. of racemes / plant§ --- --- --- --- --- --- 1860.3338 5170.4946 0.26

5. Raceme length (cm) 5.0338 -0.1170 1.02 5.8687 -2.3802 1.68 5.4165 -1.9194 1.55

6. No. of flowers / raceme 64.8067 -25.0350 1.63 72.2724 -16.2600 1.29 64.1521 -21.9462 1.52

7. No. of pods / raceme 10.6362 -9.6648 10.95 2.3603 -9.4308 -0.33 4.7893 -6.8694 -2.30

8. No. of seeds / pod -0.3117 4.2690 -0.08 0.3131 -0.2568 5.56 0.2513 0.0570 0.81

9. Seed index 0.1120 -0.0198 1.21 0.1245 -0.0960 4.37 0.1135 -0.0978 7.23

10. Seed yield / plant (gm) 0.4199 0.8826 0.32 0.5737 -1.2432 -0.86 0.5978 -0.7488 -3.96

11. Seed yield / plot (gm) 354.8407 839.8395 0.30 522.0773 -1135.5864 -0.85 520.8222 -610.7311 -5.79

12. Phytomass / plot (kg) § --- --- --- --- --- --- --- --- ---

13. Harvest index -0.00017 0.0006 -0.39 0.00011 -0.00012 -11.00 0.000045 -0.000012 1.28

§: Because, the genotype effect was non-significant for these generations, thus, these generations were not consid

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Table (4): Proportional contribution of males (M), females (F) and their interactions (M x F) to total variance for seed yield and seed yield

components of alfalfa in BC1F2 and BC2F2-generations and across two-generations under field environmental conditions.

Traits BC1F2-generation BC2F2-generation Across two-generations M F M x F M F M x F M F M x F 1. Flowering date (days)§ 14.04 64.59 21.37 --- --- --- 1.34 84.80 13.86

2. Plant height (cm)§ --- --- --- --- --- --- --- --- ---

3. Number. of shoots / plant§ --- --- --- 26.95 59.24 13.81 25.16 54.89 19.95

4. Number of racemes / plant§ --- --- --- --- --- --- 5.92 69.26 24.82

5. Raceme length (cm) 69.83 21.28 8.89 82.75 15.21 2.04 89.77 9.39 0.84

6. Number of flowers / raceme 67.98 29.98 2.04 81.55 14.16 4.29 87.35 12.15 0.50

7. Number of pods / raceme 49.61 42.23 8.16 21.87 48.44 29.69 45.52 37.36 17.12

8. Number of seeds / pod 26.69 42.44 30.87 75.97 23.31 0.72 54.57 31.18 14.25

9. Seed index 49.21 38.89 11.90 76.63 17.63 5.74 83.28 16.32 0.40

10. Seed yield / plant (gm) 16.66 57.19 26.15 55.94 41.09 2.97 37.05 52.33 10.62

11. Seed yield / plot (gm) 16.83 56.42 26.75 60.24 37.87 1.89 37.74 50.06 12.20

12. Aboveground phytomass / plot (kg) § --- --- --- --- --- --- --- --- ---

13. Harvest index 6.39 35.46 58.15 66.23 31.17 2.60 50.75 23.88 25.37

§: Because, the genotype effect was non-significant for these generations, thus, these generations were not considered for subsequent analyses.


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Table (5): Estimates of general (δ2gca) and specific (δ2sca) combining ability variances and narrow-sense (hN.S.) and broad-sense (hB.S.)

heritabilities in the factorial crosses for seed yield and seed yield components of alfalfa in BC1F2 and BC2F2-generations and across two-

generations under field environmental conditions.

Traits BC1F2-generation BC2F2-generation Across two-generations δ2gca δ2sca hN.S. hB.S. δ2gca δ2sca hN.S. hB.S. δ2gca δ2sca hN.S. hB.S.

1. Flowering date (days)§ 10.6198 15.1458 0.45 0.79 --- --- --- --- 5.5520 2.0551 0.56 0.65

2. Plant height (cm)§ --- --- --- --- --- --- --- --- --- --- --- ---

3. No. of shoots / plant§ --- --- --- --- 1.6874 0.1076 0.57 0.64 1.0859 0.4492 0.44 0.59

4. No. of racemes / plant§ --- --- --- --- --- --- --- --- 608.708 861.749 0.35 0.57

5. Raceme length (cm) 1.2552 -0.0195 0.74 0.76 1.4010 -0.3967 0.93 0.74 1.3008 -0.3199 0.97 0.80

6. No. of flowers / raceme 15.5062 -4.1725 0.93 0.80 17.3906 -2.7100 0.87 0.82 15.4284 -3.6577 0.98 0.85

7. No. of pods / raceme 2.3906 -1.6108 0.69 0.79 0.3281 -1.5718 -0.16 0.72 1.0065 -1.1449 0.39 0.80

8. No. of seeds / pod 0.0406 0.7115 0.27 0.82 0.0711 -0.0428 0.97 0.70 0.0644 0.0095 0.60 0.79

9. Seed index 0.0274 -0.0033 0.63 0.64 0.0284 -0.0160 0.80 0.57 0.0256 -0.0163 0.98 0.61

10. Seed yield / plant (gm) 0.1295 0.1471 0.32 0.66 0.1088 -0.2072 0.77 0.53 0.1286 -0.1249 0.57 0.62

11. Seed yield / plot (gm) 112.039 139.973 0.31 0.65 98.975 -189.264 0.85 0.53 113.241 -101.788 0.53 0.62

12. Phytomass / plot (kg)§ --- --- --- --- --- --- --- --- --- --- --- ---

13. Harvest index -0.00002 0.00010 0.05 0.70 0.00002 -0.00002 0.87 0.71 0.000011 -0.000002 0.33 0.69

§: Because, the genotype effect was non-significant for these generations, thus, these generations were not considered for subsequent analyses.

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الملخص العربى

التباين الوراثي وكفاءة التوريث لمحصول البذرة ومكوناته في البرسيم الحجازي

1 أحمد محروس رماح،2 زيجمونت ستاشيفسكى،1 محمد أبو زيد النحراوي،1مدمجدي ماهر مسعد مح

- جيزة - مركز البحوث الزراعية - معهد بحوث المحاصيل الحقلية - قسم بحوث محاصيل العلف -1 .مصر

. بولندا- وارسو - راجيكوف - معهد األقلمة وتربية النبات -2

محصول البذرة ومكوناته في البرسيم الحجازي من الدراسات تعتبر دراسة العوامل الوراثية المؤثرة على .ذات األهمية لتحسين محصول البذرة

: أظهرت نتائج الدراسة األتي

تحكم الفعل الجيني المضيف والسيادي في وراثة بعض مكونات محصول البذرة باستثناء صفات النورة • .ي الضيق لهذه الصفاتالزهرية مما نتج عنه قيم متوسطة لكفاءة التوريث بالمعن

كان التباين الوراثي الراجع لآلباء غير الرجعية اكبر من تباين التفاعل بين اآلباء واألمهات لكل صفات •النورة الزهرية تحت الدراسة مما كان له األثر في تسيد الفعل الجيني المضيف علي الفعل الجيني السيادي

اب لصفات النورة الزهرية يمكن إجراؤه باستخدام طرق في وراثة هذه الصفات وبناء عليه فأن االنتخ . التربية المصممة الستغالل التباين الوراثي المضيف

تدل قيمة كفاءة التوريث بالمعني الضيق السالبة والمتحصل عليها في الجيل الثاني للجيل الرجعي الثاني •قة بالصفة المدروسة حيث كان تأثير نورة علي عدم وجود اختالفات وراثية ذات العال / لصفة عدد القرون

كل من اآلباء واألمهات والتفاعل بينهما غير معنوي، كما أنه يوجد سبب أخر لكفاءة التوريث السالبة وهو . إنتاج أباء عالية األقلمة أبناء ضعيفة األقلمة بسبب االختالف الكامل للظروف البيئية لنمو الجيلين

ية لبعض مكونات محصول البذرة علي استجابة هذه الصفات لالنتخاب مع أي تدل قيم كفاءة التوريث العال • .برنامج للتربية

تعتبر صفات النورة الزهرية عامل مهم جدا للتربية لمحصول البذرة في البرسيم الحجازي، حيث كانت قيم •ت بالعشائر التجريبية كفاءة التوريث بالمعني العام والمعني الضيق عالية باإلضافة إلي ذلك، تأثر هذه الصفا .أو التراكيب الوراثية الحاملة للجينات المرغوبة مثل النورة الزهرية الطويلة والمتفرعة

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The 11th International Conference of Agronomy Sciences