Effect of terminal drought stress on grain yield and baking quality of hexaploid wheat genotypes

To study the response of 180 genotypes of hexaploid wheat to terminal drought stress for grain yield and baking quality properties, a field experiment was conducted at reasearch field station of Seed and Plant Improvement Institute (SPII), Karaj, Iran in 2005-2006 cropping season. Genotypes were planted in two separated experiments simulating non-stress and stress (applied from anthesis to physiologic maturity) conditions using an unreplicated systematic experimental design. Following identification and classification of genotypes in three groups: tolerant genotypes with reasonable yield potential (group A of Fernandez), genotypes with reasonable yield potential and susceptible to drought stress (group B of Fernandez) and moderately tolerant genotypes, genotypes of these three groups were evaluated for baking quality properties. Results of this experiments showed the theory of ''improving bread quality properties of bread wheat under stress conditions'' is only applicable to susceptible genotypes and to some extents to moderately tolerant genotypes, due mainly to increased grain protein content followed by reduction of 1000 grain weight in stress conditions. This theory is not relevant to drought tolerant genotypes, because in these genotypes no considerable change in proportion of protein content to carbohydrates was observed, under stress conditions. The results of this study suggested that identification and selection of genotypess with high grain yield and desirable baking quality properties under non-stress and stress conditions practicable. In this study 7 drought tolerant genotypes with good baking quality were identified in both non-stress and stress conditions. Although susceptible genotypes may gain better baking quality properties under stress conditions, but this is usually compensated by yield penalty.