Natural variability and heritability of root-nodulation traits in chickpea (Cicer arietinum L.) minicore

The existence of large variations for nodulation traits in chickpea minicore was revealed and genetic materials for beneficial biological nitrogen fixation (BNF) traits like early nodulation, high nodulation, and delayed nodule senescence were identified. Early-nodulating genotypes viz. ICC12968, ICC7867, ICC13816, ICC867, ICC15264, ICC15510, and ICC283 produced > 10 nodule number per plant (NNPP) at 15 as well as 30 days after sowing (DAS). Maximum of 36 NNPP at stage 3 i.e., 253% higher than check cultivar were observed in Iran originated ICC6874. Chickpea minicore showed large variations for nodule mass that ranged up to 850 mg/plant at 60 DAS and 2290 mg/plant at 90 DAS. Strong positive correlation was found between nodule fresh weight and specific weight at stage 3 (0.69) and stage 4 (0.76). Besides these, few slight positive significant correlations were also observed viz., nodule number per plant at stage 3 and 4 (0.45), nodule fresh weight at stage 3 and 4 (0.39). Principal component analysis (PCA) indicated that dimensions 1 (21%), 2 (17.6%), and 3 (13%) accounted for a substantial portion of the phenotypic variance, each contributing more than 10%. Accessions viz. ICC1431, ICC13599, ICC13764, and ICC13863 with pink active root nodules and high nodule biomass at later crop growth stages are considered as genetic resources to extend the BNF support in chickpea. High broad-sense heritability values of 76.43 and 90.23 were observed for early nodulation and delayed nodule senescence, respectively. Hence, the identified genotypes for early nodulation and delayed nodule senescence can be used for improving symbiotic efficiency in chickpea.