Genetic divergence and stability analysis in advanced breeding lines of soybean
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Date
2015
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JNKVV
Abstract
ABSTRACT
The present investigation entitled “Genetic Divergence and Stability Analyses in Advanced Breeding Lines of Soybean” was carried out under AICRP Project on Soybean, Department of Plant Breeding & Genetics at Seed Breeding Farm, College of Agriculture, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (M.P) during the rabi 2013-14 (E1), kharif 2014 (E2) and rabi 2014-2015 (E3). The experimental design comprised 50 different genotypes of soybean (6 popular varieties and 44 advanced breeding lines) were grown in a Randomized Complete Block Design with three replication during rabi 2013-14 (E1), kharif 2014 (E2) and rabi 2014-2015 (E3). Each plot consists of two rows of 2.0 m length and 40 cm apart in among rabi 2013-14 [E1], kharif 2014 [E2] and rabi 2014-2015 [E3]. Five competitive plants were selected from each replication for 18 quantitative traits viz; days to 50% flowering, days to maturity, plant height, number of branches per plant, number of nodes per plant, number of pods per plant, number of pods per node, number of seeds per plant, number of seeds per pod, 100 seed weight, biological yield per plant, harvest index, seed yield per plant, protein content, oil content, carbohydrate, ash content and fibre. Characterization was done on the basis of following characters such as hypocotyl colour, growth type, growth habit, pubescent, pubescent colour, leaf shape, flower colour, pod colour, seed coat colour, seed size, seed shape and hilum colour.
Data were subject to analysis to find out estimate the genetic variability, heritability, genetic advance, correlation coefficient, path coefficient analysis, genetic diversity, principal component analysis, stability analysis and molecular diversity using RAPD and SSR markers.
The analysis of variance indicated that the mean sum of squares due to genotypes were highly significant for days to 50% flowering, days to maturity, plant height, number of branches per plant, number of pods per plant, number of pods per node, number of seeds per pod, biological yield per plant, harvest index, seed yield per plant and fibre in all the environmental conditions. Number of nodes per plant, number of seeds per plant, 100 seed weight,
protein, oil, carbohydrate and ash were highly significant in E1, E2 and pooled environment while significant at 1% level in E3 environment.
The phenotypic coefficient of variability was greater than genotypic coefficient of variability for all the traits in all environments. The high magnitude of both coefficients were recorded for traits viz., seed yield per plant, biological yield per plant, number of seeds per plant and number of seeds per pod in all environments. The high magnitude of both coefficients were recorded for number of branches per plant, number of pods per plant in E1, E2 and E3 environment, harvest index in E1 and E3 environment, number of pods per node in E1 and E2 environment, 100 seed weight in E2 environment. The moderate magnitudes of both coefficients were recorded for plant height in all environments. The moderate magnitudes of both coefficients were recorded for number of nodes per plant, fibre in E1, E2 and E3 environment while harvest index showed moderate magnitude for both coefficients in E1 environment.
High heritability with high genetic advance was recorded for biological yield per plant, plant height, number of pods per plant, number of seeds per plant and seed yield per plant in E1, E2, and E3 (Table 5.1). Whereas, high estimate of heritability along with high genetic advance was recorded for harvest index in E1 and E3, number of pods per node and 100 seed weight in E2 and number of branches per plant in E3, days to 50% flowering in pooled. High heritability with moderate genetic advance was recorded for fibre content in E1, E2, and E3, number of nodes per plant in E1 and E3 and days to maturity in pooled. Moderate heritability with moderate genetic advance was recorded for number of nodes per plant in E1, E2 and E3, number of pods per node in E1 and E3. High heritability with low genetic advance was recorded for protein content, oil content in E1, E2 and E3. Plant height, number of pods per plant, number of pods per node and fibre content in pooled analysis recorded high heritability with low genetic advance indicating that they may be governed by non-additive gene action.
In the present findings the significant phenotypic correlation of seed yield per plant were found positive for the characters number of branches per plant, number of nodes per plant, number of pods per plant, number of pods per
node, number of seeds per plant, biological yield per plant and harvest index in all the environments. Whereas, 100 seed weight showed positive significant correlation with seed yield per plant in E1 and E2. Number of seeds per pod showed positive significant association with seed yield per plant in E1 and E3. This suggests that these characters should be considered while selecting for improvement in seed yield per plant provided the character should show high variability, which is the basis for selection. However, 100 seed weight showed negative correlation with seed yield per plant in E2 environment.
The path coefficient analysis of different characters revealed that highest positive direct effect on seed yield per plant per plant was exerted by number of pods per plant followed by number of seeds per plant, number of pods per node, number of nodes per plant, biological yield per plant, harvest index and
100 seed weight in all the environments. Number of seeds per pod and protein content exhibited substantial positive direct effect on seed yield per plant in E1 and E3 environment. Carbohydrate exhibited low positive direct effect on seed yield per plant in E2 and E3 environment. Fibre exhibited low positive direct effect on seed yield per plant in E1 and E2 environment. We can conclude on the basis of present finding that number of pods per plant, number of seeds per plant, number of pods per node, number of nodes per plant, biological yield per plant, harvest index and 100 seed weight are universal traits for overall improvement, whereas, Number of seeds per pod and protein content are important for E1 and E3 environment. Carbohydrate E2 and E3 environment, fibre in E1 and E2 environment should be given specific importance in addition to number of pods per plant, number of seeds per plant, number of pods per node, number of nodes per plant, biological yield per plant, harvest index and
100 seed weight while mounting selection for specific conditions. Negative direct effect on seed yield per plant per plant was exerted by plant height, oil and ash content in E1, E2 and E3 environment. Days to maturity imposed negative direct effect on seed yield per plant in E1 and E2 environment.
Genetic divergence analysis based on Mahalanobis D2 statistics, fifty genotypes were grouped into ten clusters in rabi 2013-14 (E1), six clusters in kharif 2014 (E2), thirteen clusters in rabi 2014-2015 (E3) and twelve clusters in pooled revealing the presence of wide genetic diversity.
Cluster VI in rabi 2013-14 (E1), cluster III in kharif 2014 (E2), cluster XIII in rabi 2014-15 (E3) and cluster V in pooled recorded the highest mean values for seed yield per plant, biological yield per plant, protein content, days to maturity, oil content, days to 50% flowering and plant height (characters which contributed to genetic diversity) and are the superior clusters. The genotypes in these clusters could be widely used in crossing programme for generation of wide spectrum of variability in yield.
The characters viz., days to 50% flowering, days to maturity, plant height, number of branches per plant, number of nodes per plant, number of pods per plant, number of pods per node, number of seeds per plant, biological yield per plant, harvest index and number of seeds per pod are more important yield contributing traits based on principal component analysis. Genotypes namely 20-89, JS 20-115, JS 20-108, JS 20-122, JS 20-79 and JS 20-121 were found promising, which can be further promoted as variety or may be utilized as further breeding program.
The analysis of variance for phenotypic stability revealed that the mean differences due to genotypes were statistically significant for all the traits. The significance of G X E interaction was detected for most of the traits except quality traits, which suggested differential responses of genotypes in different environments. The magnitudes of linear components were more than non- linear components for all the characters.
Stability analysis revealed that genotypes JS 20-113, JS 20-41 and JS
20-96 were found as stable genotypes which exhibited stable performance for more than four characters including most important yield and yield contributing traits. Genotypes JS 20-65, JS 20-87, JS 20-102 and JS 20-109 exhibited above average stability for yield and other yield contributing traits and therefore these genotypes specifically adapted to unfavorable environmental conditions.
Five randomly selected decamer primers amplified 43 RAPD marker loci, with amplified fragments ranging in size from 100-3000bp. Out of these 43 bands, 23 bands (54.88 %) were polymorphic, revealing the presence of diversity among the genotypes under investigation.
The number of bands amplified from each primer varied from 5 for OPF-
09 to 9 for OPA-13. The average number of bands amplified per primer was
8.63. The average number of polymorphic RAPD bands was 3.28 per primer. Primer OPAG-09 produced the lowest level of polymorphism (0.00%). Other primers produced 71.4, 80.0 and 87.5% polymorphism. The range of genetic similarity was 0.161-0.960 indicating that there is significant variability among the soybean cultivars.
A total of 10 SSR primers amplified 15 SSR markers loci. The size of the amplified markers ranged from100-400 bp. Maximum numbers of bands i.e. 2 were amplified by all polymorphic primers Soy satt 005, Soy satt 173 and Soy satt 185, Satt168 and Satt173 while minimum number of bands i.e. 1 was obtained with all monomorphic primers. Out of these 15 loci, 10 loci were found polymorphic (66.66%) across all the soybean cultivars. Percentage polymorphism ranged from 0 to as high as 100 (primer Soy satt 005, Soy satt
173 and Soy satt 185, Satt168 and Satt173). Average number of total bands per primer was 1.5, while average number of polymorphic bands per primer was 1.0.
Characterization of several agro-morphological traits is helpful in tracing correlation and linkages between different traits. Genotypes are characterized on the basis of morphological traits viz., hypocotyl colour, growth type, growth habit, pubescence, pubescence colour, leaf shape, flower colour, pod colour, seed coat colour, seed size, seed shape and hilum colour. From the study of these characters we can easily identify different genotypes of soybean. So, we can use these characters as an identification keys.