Indoor characterization of three durum wheat genotypes exposed to drought and heat stress during early vegetative growth stages

Selection of wheat varieties that have improved adaptation to abiotic stress is important for increasing and stabilizing yields under fluctuating environmental conditions, especially as global climate changes. A trial to estimate adaptation of wheat (Triticum turgidum subsp. durum) genotypes to abiotic stress has been performed, in a growth chamber. By counting the number of dead (yellow) plants, together with yellow and green leaves, and hence traits that easily can be also detected by automatized phenotyping platforms, were analyzed for the effects of optimal watering, progressive water deficit and different levels of heat stress. “Trinakria” variety and two Trinakria mutants (“Water-mutant” and “Hg-mutant”) altered for water-related physiological traits were examined. The use of very genetically close genotypes had the aim to minimize differences in stress response due to asynchronous phenological development and to evaluate better the protocol usefulness to detect minimal phenotypic differences, such as those found between advanced breeding lines, at the final stages of a breeding program. Results showed that Trinakria had a significantly greater % of green leaves under drought stress and retained green leaf after heat stress ceased. In contrast, the two mutants had improved plant survival after moderate heat stress. In conclusion, an examination of leaf color changes under moderate water deficit and heat stress was sufficient in a differential comparison of genotypic performances.   Key words: Abiotic stress, leaf color, phenotyping, wheat.