Abstract

Rising global temperature due to climate change highlight the need to develop and identify heat-tolerant genotypes in cotton to maintain productivity under heat stress environment. To achieve this objective, six heat tolerant parents (lines) namely, AGC-999, VH-329, MNH-886, FH-Lalazar, FH-142 and Shahkar were hybridized with three parents (tester), namely Rehmani, Coker-304 and NIAB-Kiran. The resulting F1 population was evaluated in field condition following split-plot RCBD experimental design. Two planting dates were selected: early sowing for heat stress (≥ 40°C at flowering) and late sowing as a control (< 40°C at flowering). The physiological and biochemical analyses were determined after the initiation of flowering and yield data was also recorded at harvest under both conditions. The statistical analyses were performed on collected data to detect the response of genotype, presence of genetic diversity and gene action. The findings revealed that heat stress negatively affects the performance of cotton key traits, like cell membrane thermostability (−55.9%), seed cotton yield (−12.02%), and pollen viability (-10.48%), while peroxidase and proline content increased by +97.27% and +11%. The findings also highlight that heat stress increased the genotypic variance among the genotypes. Further, most traits exhibited non-additive gene action, although additive effects were also important for ginning turnout and seed cotton yield. The parents namely VH-329, AGC-999 and FH-Lalazar exhibited high general combining ability under stress. These parents might be useful for the development of synthetic populations through recurrent selection for the accumulation of favorable genes against heat stress.