Evaluation of the relationship between gas exchange variables with grain yield in barley genotypes under terminal drought stress

Drought stress is one of the major abiotic stresses in agriculture worldwide. This study was carried out to investigate the effect of drought stress at grain filling period on photosynthesis, gas exchange parameters and grain yield in twelve varieties of barley. To this end, an experiment was laid out in a split-plot arrangement based on randomized complete blocks design with three replications during 2010 to 2011 seasons at the field research of Razi University, Kermanshah state in the west of Iran. The results showed that post anthesis water deficiency caused 22 percent reduction in grain yield and had not signification effect on plant height. In addition, drought stress at grain filling period can considerably decreased leaf photosynthesis rate (Pn), stomatal conductance (gs) and transpiration rate (Tr), and increased sub-stomatal CO2 concentration (Ci). The results showed that by imposing water deficit, Pn, gs and Tr was reduced in all studied barley genotypes. Pn, gs and Tr were statistically higher in full irrigation treatment as compared to drought stress by an average of 32.3, 19 and 15%, respectively. The decrease in the net photosynthetic rate in the grain filling stage of drought stress was related to the closure of stomata and decreased stomatal conductance. Our data revealed the better performance of ‘Karoun’ than ‘Nosrat’, ‘Sararud’ and other genotypes in the reduction rate of grain yield at maturity and photosynthetic features against soil water deficit conditions.

Barley, Grain yield, Photosynthetic rate, Stomatal conductance, Drought stress