Heritability and correlation for nitrogen (N2) fixation and related traits in peanut (Arachis hypogaea L.)

The objectives of this study were to estimate broad sense heritability for N2 fixation and related traits and agronomic traits and evaluate correlations among these traits. Seventy four progenies in the F, generation previously selected in the F4 generation for high and low performance for N fixation and related traits were tested for N2 fixation and related traits and their agronomic performances. A non-nodulating line was also included as a reference crop for nitrogen determination. The experiment was carried out under limited soil nitrogen conditions. A randomized complete block design with four replications was used. Data were recorded for leaf color score, nodule dry weight, top dry weight, fixed nitrogen, pod number, pod weight, seed weight, seed size, shelling percentage and harvest index. Most heritability estimates for N2 fixation and related traits were moderate and high ranging from 0.33 to 1.00 except one low estimate (0.33). Most heritability estimates for agronomic traits were also moderate and high ranging from 0.37 to 1.00 except two low estimates (0.37 and 0.50). High heritability estimates in the F5 generation indicated that genetic variations of this population after divergence selection in the F4 generation are conserved and further selection for N2 fixation and agronomic traits in this population is possible when individual characters are considered. High and positive correlations among fixed nitrogen and its components were found indicating that increase in one trait can increase others. Correlations between N2 fixation and pod yield were low and varied depending on crosses suggesting that selection for both N2 fixation and pod yield is essential.