Application of Stress Indices to Identify Terminal Heat Tolerance Genotype in Field Pea (Pisum sativum var. arvense)

Abstract

Background: The exposure of field pea crop to high-temperature stress during the anthesis and pod development stage led to poor pollination, development of shriveled pods and poor performance that results in reduced seed yield. The study aims to screen and identify heat-tolerant genotypes based on stress tolerance indices. One hundred forty-three field pea genotypes, including three checks evaluated in augmented block design for seed yield per plant under normal and late sown conditions to identify terminal heat-tolerant genotypes of field pea. Methods: Stress indices were computed based on seed yield per plant under normal (Yp) and late (Ys) sown conditions. The stress indices for seed yield are calculated as per the suggested method i.e. tolerance index (Hossain et al., 1990), heat susceptibility index (Fischer and Maurer, 1978), yield stability index (Bouslama and Schapaugh, 1984), mean productivity (Hossain et al., 1990), geometric mean productivity (Fernandez, 1992), stress tolerance index (Fernandez, 1992). Correlation coefficient and principal component analysis were done by using R (version 4.1.1) statistical software. Result: Correlation coefficient analysis reveals that seed yield under stress conditions was positively correlated with the indices viz., MP, GMP, STI and YSI whereas, it was negatively correlated with HSI, signifying that higher estimates of MP, GMP, STI and YSI and lower of HSI correspond to heat tolerance. The seed yield under both environments had a positive and significant association with MP, GMP and STI. Genotypes viz., EC-341743, P-1679, P-1384-3, P-179 and P-781 were found with high indices scores and showing their suitability for the breeding program for heat tolerance. The first two principal components (PCs) accounted for 97.46% of the total variation present in the genotype.