Authors:M. Modarresi, V. Mohammadi, A. Zali, and M. Mardi
High temperature is a major determinant of wheat development and growth and causes yield loss in many regions of the world. This study was conducted to assess heat stress effects on yield and yield related traits of wheat. The 144 recombinant inbred lines derived from the cross of Kauz (heat tolerant) and MTRWA116 (susceptible) together with some commercial cultivars were evaluated during 2006–2007, 2007–2008 under normal and heat stress (late sowing) conditions. Grain yield, head length, kernels per spike, spiklets per spike, plant height, grain filling duration, peduncle length and 1000 kernels weight were measured. The results showed a significant difference among RILs for all traits in stress and control conditions. High temperature significantly decreased all traits specially grain yield (46.63%), 1000-kernel weight (20.61%) and grain filling duration (20.42%). Grain yield was most affected and spikelets per spike was least affected (11.77%). Grain yield under heat stress was directly correlated (r = 0.49) with yield in normal condition. Head length and grain yield had the highest (93.18%) and the lowest (62.97%) heritability, respectively. Peduncle length and grain filling duration showed the highest correlation with yield under both normal and heat stress conditions suggesting that these two traits could be used as reliable screening tools for development of heat-tolerant genotypes.