The efficiency of canopy temperature and relative water content in screening of wheat genotypes for heat tolerance

Terminal heat stress is one of the most important environmental factors threatening wheat production in Iran and all across the world. In order to study the effectiveness of canopy temperature and Relative water content in screening wheat lines for heat tolerant, ten wheat genotypes were evaluated in three separate randomized complete block design experiments in two years (2015-16 and 2016-17) under non- stress and heat stress conditions at Gonbad and Atrak research stations. Heat stress was applied through three methods including late sowing, plastic greenhouse and field temperature. Canopy temperature, relative water content and grain yield of genotypes were measured. All genotypes showed significant reductions in grain yield under heat stress. Based on grain yield under stress and non-stress conditions, yield loss percentage and Fisher and Maurer susceptibility index, Kauz, Shiroudi and N-92-7 were shown to be tolerant, while Bam and Verinak susceptible to heat stress. Although both canopy temperature and relative water content had a significant correlation with grain yield under heat stress, canopy temperature was significantly different between tolerant and sensitive genotypes, indicating its higher efficiency in screening for heat tolerance.