Response of heat-stress tolerant and susceptible wheat lines in diverse planting environments by using parametric stability models

Abstract

In Pakistan, wheat planting is delayed because of dawn sowing, which reduces yield due to terminal heat stress. This effect can be alleviated by changing sowing times. Therefore, parametric stability analysis was carried out with eight different sowing dates (environments), namely, early, normal, late, and very late, with 10-day intervals in 2019–2020 and 2020–2021 at the Wheat Research Institute, Faisalabad, Pakistan. Significant heat stress responses were observed at the latter two sowing dates. The genetic and phenotypic relationship among the traits revealed that the normalized vegetation index (NI) had a positive correlation with grain yield (kg ha−1) (Yi) and 1000-grain weight (g) (GrWt). However, canopy temperature (CaTe) had a negative correlation with Yi, GrWt, and NI. For Yi and GrWt, the linear environmental response (α) and deviation from linear response (λ) were observed as transformed forms of regression coefficient (bi) and deviation from regression (S2d). Planting dates, i.e., E1, E6, and E7, had slight effects on Yi, and E6, E7, E2, and E8 had slight effects on GrWt. Meanwhile, E3, E4, E5, E1, E3, and E4 exerted a strong effect on the genotype by environment interactions for Yi and GrWt. For Yi, lines G23, G20, and G21 were adapted to E8; G9 and G19 were adapted to E1; and G15, G17, and G22 were adapted to E5. For GrWt, G13, G20, G3, G11, G21, and G15 were adapted to E8 and E4; G10, G7, G8, and G5 were adapted to E5; G4, G22, and G17 were adapted to E6 and E4; and G24 and G2 were adapted to E2 and E3. The candidate wheat lines with enhanced GrWt and Yi were found in E5 and E6 (late sowing) and E7 and E8 (very late) and presented tolerance to terminal heat stress.