Comparative Study on the Effect of Soil Water Stress on Photosynthetic Function of Triticale, Bread Wheat, and Barley

In order to compare photosynthetic features of triticale, bread wheat, and barley under water deficit conditions, this experiment was carried out in Kurdistan province in western Iran. Four genotypes of triticale, three cultivars of bread wheat, and a new variety of barley were compared under well watered (Ψsoil= -3 bars) and soil water deficit (Ψsoil= -12 bars) conditions in a randomized complete block design (RCBD) with a split-plot arrangement. Biomass production at anthesis accompanied with gas exchanges and chlorophyll fluorescence of flag leaves, as indicators of photosynthetic function of plant, were determined in each treatment. The results showed that by imposing water deficit, photosynthetic rate (Pn) was reduced in all studied genotypes irrespective of plant species. Under water deficit conditions, the highest Pn (6.86 and 5.90 µmol m-2 s-1) was found in bread wheat variety Pishgam and, triticale genotype No. 1, while the lowest value (3.63 µmol m-2 s-1) was found in barley variety Bahman. Similar trend was observed for the maximum quantum yield of primary photochemistry (Fv/Fm) and performance index (PI). Significant positive correlations were found between biomass production at anthesis and both Pn (r= 0.83**) and Fv/Fm (r= 0.77*). Our data revealed the better performance of Pishgam than Alvand and Zarrin in the reduction rate of biomass at anthesis and photosynthetic features against soil water deficit conditions. Overall, triticale was less affected by water deficit in comparison with wheat and barley in terms of photosynthetic function as indicated by less reduction in Pn, PI, and Fv/Fm.