Onkar Singh

Genetic analysis of agronomic characters in chickpea. II. Estimates of genetic variances from line × tester mating designs.

SummaryThirty line x tester experiments involving diverse chickpea (Cicer arietinum L.) germplasm were conducted over 8 years and three locations to determine the nature of the genetic variance for grain yield and related characters, and the effects of generation and environment on these genetic parameters. Days-to-flowering, 100-seed mass, and seeds per pod were predominantly under the control of additive genetic variance, while both additive and non-additive genetic components of variance were important for days-to-maturity, plant height, primary and secondary branches, pods per plant, and seed yield. The F1 and F2 generations were found equally useful in estimating the genetic variances for different characters because the generation did not significantly interact with genetic parameters in the majority of cases. Sites or seasons, on the other hand, showed significant interaction with genetic components of variances; additive variance showed a larger interaction with environments than non-additive variance. This indicated the importance of more than one site and/ or season for unbiased estimation of the genetic components of variance. The results were compared with previous findings from diallel analyses.

Genetic analysis of agronomic characters in chickpea

SummaryTwenty-eight diallel trials over 8 years and two locations were analysed to estimate genetic variances for agronomic characters of chickpea (Cicer arietinum L.). The data were analysed according to Method 4 and Model I of Griffing (1956). Days to flowering, plant height, and seed size were found to be predominantly under additive inheritance and were highly predictable. Both additive and non-additive genetic components were important for seed yield, number of branches, pods per plant, and seeds per pod. Although both general combining ability (gca) and specific combining ability (sca) varied significantly with generation, components of gca mean squares were invariably much larger than gca x generation interaction components, indicating that either the F1 or the F2 generation can be used to estimate the gca components effectively. Combined diallel analysis of F2s over locations revealed the importance of combining ability x location interactions and emphasized the need for testing over more than one location for the precise estimation of combining ability. The implications of these findings and those reported earlier in the literature on the breeding strategies/methods for the genetic improvement of agronomic characters in chickpea are discussed.

Stability analysis of backcross population for salinity tolerance at reproductive stage in rice

Significant yield reduction was recorded at flowering stage in rice varieties under salinity stress. But due to high genotype x environment interaction (GEI) the adaptability of the salt tolerant elite lines is generally poor. The identified source of tolerance, AC41585, was used in developing a backcross population. One hundred eighty BC3F4 lines were evaluated under stress (EC 8dSm−1) and non-stress conditions in net-house during the years 2012 and 2013. Under salinity stress plant yield was observed to be associated positively with the number of panicles/plant, panicle length, harvest index and negatively with the percentage of spikelet sterility and degeneration. Genotypes such as, L-41, L-45, L-112, L-171, L-192 with low IPCA and higher mean were identified with general adaptability through AMMI analysis. In addition, ‘which-won-where’ pattern of GGE Biplot detected L-192 and L-41 as highest performing genotypes in saline and non-saline environments, respectively. Both the analyses identified stable introgression line L-171 with high yield stability index having phenotypic similarity with recurrent parent, IR 64. The elite lines selected through the present study could be used in rice breeding and also to investigate the molecular basis of salt tolerance at reproductive stage.

Root-knot nematode disease of chickpea in Nepal

The root-knot nematode disease of chickpea (Cicer arietinum) caused by Meloidogyne spp. was found to be widespread in the Tarai region of Nepal. The disease was moderate to severe in Bhairahawa, Gadari, Gopalkoti, and Rampur. In Nawalpur, Nepalganj and Parwanipur, the disease incidence was low. Leucas aspera, a common weed in chickpea fields, was found to harbour the root-knot nematode