Effects of water stress and different mycorrhiza species on grain yield, yield components, chlorophyll content and biochemical components of sunflower

To evaluate the effects of water stress and two kinds of mycorhiza species on grain yield, yield components, chlorophyll content, chlorophyll fluorescence, proline and carbohydrate concentration in sunflower (Helliantus annus Var. Alster), a field experimental as a split plot design was conducted with three replications in 2011 at the Research Farm of the University of Zabol. Water stress treatments included 90 (control), 70 and 50 percent of the field capacity as the main plot and two different mycorrhiza species, including Glumus mossea and Glumus etanicatum and also a control or without any inoculation as sub plots. Results showed that water stress significantly decreased grain yield, biological yield and harvest index. The grain yield reduction was about 15.07% at the highest level of water stress in comparison with the control. However application of mycorhiza increased grain yield, biological yield and harvest index, but it had not significant effects on them. Water stress increased soluble carbohydrate and proline content in leaves, whereas significantly reduced head weight, head diameter, grains per head No. and 1000-seed weight. Using strains of mycorhiza in this study only had significant effects on proline content, head diameter, grains per head No. and 1000-seed weight. Interaction between water stress and strains of mycorhiza had only an impact on head weight and number of grains per head. So that, at the highest levels of water stress, the application of Glumus mosseahad had the highest influence on sunflower yield and yield components.