Early‐stage screening for heat tolerance in cotton

The study aimed to identify early‐stage traits of cotton for heat tolerance using multitrait approach reflecting field yield performance. Seedling growth and physiological response of 16 cultivars to high temperature were investigated at three different developmental stages and four heat stress conditions in a climate chamber. Some traits such as hypocotyl dry weight, leaf pigment contents and cellular respiration were significantly correlated with previously known yield of ten cultivars grown in the hot field conditions. Sixteen cotton cultivars were classified for their heat tolerance by principle component analysis (PCA) using yield‐correlated physiological traits. As a result, we showed that heat tolerance classification of cultivars based on PCA significantly coincided with the yield results of cultivars grown in hot field. As a conclusion, yield‐correlated physiological traits determined in the study may facilitate selection of heat‐tolerant cotton genotypes at early stage. In addition, yield‐correlated early‐stage traits can be used in phenotyping for QTL and association mapping studies to develop selection markers for heat tolerance.