Under High Temperature Stress Condition evaluation of Morphological Responses of Cotton (Gossypium hirsutum L.) Genotypes

Abstract

Cotton cultivation formed an important part of many ancient civilizations and has continued to strengthen the economies and industrial sectors of many countries. Both cotton fiber and cotton seed are economically important due to their extensive use in textile manufacturing and vegetable oil production. With significant alteration of climate and the cotton environmental sensitivity in cultivation, the yield maintenance becomes a great challenge. While the other abiotic stresses to cotton include high temperature, which is one of the most destructive stresses that affect the growth of the plant, flower, fiber quality and yield. This research has been conducted to assess the morphological alteration in various cotton genotypes suffering temperature stress. The set up for the conduct of experiments was performed in the kharif season of 2021. To test the heat stress tolerance among the various cotton (Gossypium hirsutum L.) genotypes, one of locally available experimental fields available was chosen based upon the largest growing ecosystem location of Sindh. Heat stress significantly influenced the node number bearing the first boll. NIA-88 showed the lowest reduction in first boll node number, indicating earlier fruit initiation under stress conditions, while BT-90 and CRIS-121 were delayed. Extreme temperatures above 36 °C adversely influence key morphological and yield-related traits, making heat stress tolerance critical for cotton cultivation. In this study, six genotypes (NIA-88, BT-89, M-32, BT-90, IUB-2013, and CRIS-121) were evaluated under heat stress and non-stress conditions, showing significant variation in plant height, sympodial branches, first boll node, bolls per plant, seed index, seed cotton yield, GOT%, fruiting points, abscission points, fruit retention, and staple length. These findings indicate that each genotype contributes differently to heat tolerance, highlighting the need for multi-trait selection in breeding programs.