Effect of glycine betaine application on yield and physiological characteristics of dryland wheat cultivars in Kermanshah

To study the response of dryland wheat (Triticum aestivum L.) cultivars to the exogenous application of glycine betaine, a field experiment was conducted as a factorial based on randomized complete block design with four replications at Field Research at Islamic Azad University, Kermanshah,Iran in 2015-2016. Treatmens included four wheat cultivars, Sardari and Azar 2(drought resistant, Rasad and Owhadi(drought susceptible), and four levels of glycinebetaine application (zero or distillate water as control, 50 mM, 100 mM and 150 mM) were sprayed in two growth stages; early heading and early grain filling. The results showed that in most traits there was a significant differences between the cultivars, and Sardari cultivar was superior to other cultivars in most traits, with the highest grain yield and proline content 3571.88 kg/ha and 29.94 μmol/g respectively. Glycinebetaine spraying at 100 mM had significant increase in spike length, 1000 seeds weight, grain yield, harvest index and proline content. Interaction between cultivars and glycinebetaine concentrations showed that in 100 mM glycine betaine , only two drought resistant cultivars ,Sardari and Azar2, it was the highest and significantly different from other levels of spraying, but in the drought susceptible cultivars, Rasad and Owhadi, there was no significant difference in proline content for different levels of glycinebetaine concentrations, which may be due to the lack of changes in the incidence of related genes in response to osmotic stress. Overall,it can be concluded that there is a positive relationship between proline content and grain yield in drought resistant wheat cultivars.