Field screening for YMV resistance and mean performance on agronomic different traits
The nine black gram genotypes were scored for YMV resistance and the results are given in Table 4. The genotype IC 436656 was highly susceptible to YMV whereas the genotypes
viz., VBN 4, KKB 14-022, KKB 14-045 and KKB 14-015 were resistant to YMV. The mean performance of black gram genotypes for agronomic different traits is presented in Table 5. The genotypes IC436656, IC343943, KKM1, ADT3, KKB-14-022, KKB-14-052, KKB-14-045 and VBN 4 recorded significantly superior mean performance for days to 50% flowering
viz., 33, 35, 35, 34, 35, 32, 32.50 and 32.50 days respectively. The genotypes KKM 1, KKB-14-022 and KKB-14-045 recorded desirable mean performance for plant height
viz., 59cm, 58.40cm and 61.65cm respectively. The genotype KKB-14-045 had shown significantly superior mean performance for number of primary branches per plant (5.65) whereas the genotypes KKB-14-022, KKB-14-052 and KKB-14-045 recorded significantly more number of clusters per plant
viz., 24.80, 40.15 and 30.65 respectively. The genotypes
viz., KKB-14-052 and KKB-14-045 exhibited significantly superior mean performance for higher number of pods per plant
viz., 77.50 and 66.65 respectively and the genotypes
viz., IC436656, KKB-14-052 and VBN 4 recorded desirable performance for pod length
viz., 5.20cm, 5.15cm and 5.05cm respectively. The genotype KKB-14-045 had shown superior performance for the trait 100 seed weight (5.15g) and the genotypes IC343943, KKB-14-045 and KKB-14015 significantly well performed for single plant yield
viz., 28.10g, 31g and 31.85g respectively.
Studies on polymorphism
Genetic diversity analysis was carried out in nine black gram genotypes using 42 SSR markers. Out of 42 SSR markers, 15 exhibited 35.7 per cent polymorphism. The pictorial representation of black gram genotypes for the SSR markers CEDG 141 and CEDG 008 is depicted in Fig 1. The informativeness of the SSR markers is revealed by calculating the Polymorphic Information Content (PIC) value. The PIC value of 15 SSR markers is presented in Table 6 and the values ranged from 0.37 (CEDG 024) to 0.79 (CEDG 154) with an average of 0.63.
Pyngrope et al., (2015) screened 30 black gram genotypes using 12 SSR markers and from the study, PIC value ranged from 0.22 to 0.68 and three polymorphic markers CEDG 180, CEDG 139 and CEDG 279 were identified.
Tamilzharasi et al., (2018) genotyped 48 black gram lines for YMV resistance and tagged the molecular markers CEDG180, ISSR8111357 and YMV1 FR. In the present investigation SSR marker CEDG 139 had shown the PIC value of 0.59 (Table 6).
Cluster analysis
Genetic similarity co-efficient estimated for nine black gram genotypes ranged from 0.48 to 0.82 (Table 7). Based on similarity values, genotypes KKB-14-045 and ADT3 had less similarity (0.48) followed by KKB-14-045 and IC 343943(0.50), VBN 4 and KKM 1(0.51) and VBN 4 and KKB-14-022 (0.51). Hence these genotypes possessed high genetic variation and hybridization of these genotypes may result desirable recombinants. The genotypes KKM-1 and IC 343943 had high similarity value (0.82) and combination of these genotypes would not be advantageous for breeding programmes.
Hari et al., (2017) studied the genetic diversity analysis among YMV resistant and susceptible varieties in mung bean using SSR markers. From their studies, the mung bean variety WGG-2 was appeared to be more divergent with 42.1% similarity, while high similarity of 81.7% was recorded between two susceptible varieties KM 14-34 and KM 14-61.
In the present study, nine black gram genotypes were grouped into seven clusters at 3.80 coefficient in the dendrogram (Fig 2). Among the seven clusters, genotypes VBN 4, KKB 14-052, KKB 14-022, KKM 1, KKB 14-045 and KKB 14-015 were present separately in clusters
viz., I, II, IV,V,VI and VII respectively. The genotypes
viz., VBN 4, KKB 14-022, KKB 14-045 and KKB 14-015 were resistance to YMV and genotypes KKB 14-052 and KKM-1 were moderately resistance to YMV (Table 4). Susceptible genotypes for YMV
viz., IC 436656 (highly susceptible), IC 343943 (moderately susceptible) and ADT-3(susceptible) were grouped together in single cluster (cluster III).
Gupta et al., (2015) reported that 10 molecular markers (includes ISSR and microsatellite markers) were linked to YMV resistance in black gram and mung bean. From their studies, three molecular markers
viz., ISSR8111357, YMV1-FR and CEDG180 differentiated YMV resistant and susceptible genotypes in black gram.
Jeevitha et al., (2018) projected molecular genetic diversity analysis in black gram under an YMV hotspot regime. They analyzed 26 black gram genotypes using 19 SSR markers and the dendrogram showed four apparent clusters based on marker allele distribution and also considerable divergence was noted between the dissimilarity matrices.