Genetic Variability and Trait Association Studies of Internode Length and Strong Culm-Related Traits in Inter Sub-specific Cross Derived Recombinant Inbred Lines in Rice (Oryza sativa L.)

Internode length, plant height and culm thickness are the primary traits affecting the strength of culm in rice. The present investigation was carried out to study genetic variability and trait association of internode length and strong culm related traits in recombinant inbred lines (RILs) in rice. The lodging stress is influenced by intricate interplay of several factors and many questions remain unanswered. To elucidate the complex lodging phenomenon, traits viz., the length of uppermost internode (IL1), second internode (IL2), third internode (IL3), fourth internode (IL4), fifth internode (IL5), sixth internode (IL6), number of internodes (INN), plant height (PH), pushing resistance (PR) and culm thickness (CT) were investigated. Analysis of Variance (ANOVA) displayed significant variation in RILs for all the traits studied. The investigation revealed high estimates of PCV and GCV along with high heritability and genetic advance as percent of mean (GAM) for traits under investigation revealing the role of additive gene effect and selection of these attributes will be valuable for rice improvement. Association studies revealed that strong culm is reliant on internode length of basal primary internodes and CT. Thus, the direct selection of culm thickness and lower basal internode length can improve the breaking-type lodging resistance in rice. Our conceptual perceptions are expected to provide valuable information to improve the culm strength in rice.