Genetic divergence and character association study in soybean [Glycine max (L.) Merrill]
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Date
2020
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DRPCAU, Pusa
Abstract
Soybean [(Glycine max (L.) Merrill] a fast expanding horizontally: protein + oil source miracle crop, increasingly adopted by farmers, offers opportunity in non-traditional States like Bihar under diverse growing situations in different cropping systems, against abiotic stresses and also as contingent crop, utilized for diversified food and feed purposes.
With an aim to understand genetic variability, genetic divergence, character association and cause-effect relationship 30 soybean genotypes were collected. Field Trial (kharif 2019) conducted at TCA, Dholi, Bihar in Randomized Complete Block Design accommodating 30 genotypes randomly in three replicates. These genotypes evaluated for twenty-seven traits: five phenological, nine agro-morphological, eight physiological traits (from field trial) and five physiological traits from laboratory experiment recorded and subjected to statistical and biometrical analyses.
Considerable variability revealed usefulness of existing genetic variability for all 27 attributes amongst which vigour index II, seedling dry weight, specific leaf weight and 100- seed weight was trust worthy (GCV in close correspondence with PCV; high h2bs & high GAM reflecting Additive gene action) for selection criteria.
Positive association of flowering traits (DT→ DFB→ DFF→ DC) and uncorrelated with DPM can be precisely utilized in selection. Late physiological maturity increases seedling dry weight, plant height, clusters and seeds per pod while reduces leaf
area index, seed weight and dry matter efficiency. With an increase in primary branches corresponding more secondary branches, cluster/plant, seed weight and effective rainfall use efficiency noticed. Effective rainfall use efficiency positively with PB, SB, C/P, GER,SL, HI while growing degree days negatively with SB,PH,MSL,P/P,LAI,SW and C/P. Towards polygenic complex trait Grain Yield per Plant(GYPP)high positive correlation and highest positive direct effect of ERUE and vigour index I considered as selection criteria.
D2 –statistic (Tocher method) framed (generalized distance –based) nine clusters: largest with eight and five were oligo-genotypic. HI>GYPP>GER>SDW contributed maximum towards total divergence. From most divergent clusters, 21 crosses involving cluster v genotypes (PS-1347, RKS-18, PS-1092, NRC-142, VLS-94, NRC-136, & Shalimar Soybean-1) with monogenotypic cluster VII (AMS-2014), VIII(RSC-11-15) and III(RSC-10-71) suggested for future hybridization. Genetic divergence and geographical distribution were incomparable mainly due to free sharing of breeding lines.
Eight Principal Components explaining 85.02 percent cumulative (Spatial distance-based) variability was obtained. These PCs were best sources for specific traits, viz. ERUE, GYPP, SL, V1(PC1); DT, DFB, DFF, DC(PC2); P/C, HI, DME (PC3); SDW, V2(PC4); PB, LAI(PC5); SLW(PC6); P/P(PC7) ; DPM, SB, C/P, LAI(PC8). Yield (GYPP) related best genotype was NRC-136(In PC1, PC3 & PC7) followed by SL-955 (PC1& PC5); NRC-128(PC1, PC2 & PC6). For phenol-agro-morpho-physiological traits best source was RSC-10-71(PCs: 2, 3, 4, 6& 8) along with SL-688(PCs: 4, 5, 7 & 8); Shalimar Soybean-1 (PC3, PC7); RSC-11-17 (PC2& 3); RSC-11-15 (PC2& 6) and AMS-2014(PC2 & 7).
NRC-136, Shalimar Soybean-1(common in PCA& Cluster V: Tocher) RSC-10-71(common in PCA& ClusterIII : Tocher), RSC-11-15(common in PCA& Cluster VIII : Tocher) and AMS-2014(common in PCA& Cluster VII : Tocher) may prove their merit as diverse parents for pheno-agro-morpho-physiological traits as explained earlier toward redesigning (for yield, earliness, effective rainfall use efficiency, germination, growth and vigour) the soybean plant types.
NRC-136 and SL-955 with high grain yield, vigour, emergence, seedling, flowering –maturity traits were beneficial for cultivation on farmers’ fields in Bihar.