Assessing of the stem reserve mobilization by chemical desiccation and its relation with gaseous exchanges in different genotypes of triticale, wheat and barley under soil moisture regimes

To better understanding of drought resistance features including tolerance to chemical desiccation and transient photosynthesis under soil moisture stress in triticale in comparison with wheat and barley, an experiment was conducted during year 2009-10 in Grizeh agricultural research station located in Sanandaj. Effect of three soil moisture regimes including irrigation in soil water potential of -3 bar, -10 bar and no irrigation on eight cereal genotypes including four triticale lines, three bread wheat and one barley cultivars were studied. To stop the current photosynthesis and to assess the grain weight stability of genotypes under stress conditions, a part of control plots (irrigation in -3 bar), was sprayed by sodium chlorate 1%. Results showed that sodium chlorate reduced kernel weight and incited stem reserve mobilization rather than control by 51 and 75%, respectively. Generally, the kernel weights of triticale in both sprayed and stress conditions were higher than those of wheat and barley. By reducing transient photosynthesis under no irrigation treatment, the stem reserve mobilization was encouraged which was more pronounced for triticale rather than barley and wheat. Also under stress condition both stomatal and non stomatal factors had important role in the limitation of net photosynthetic rate.