The rol of fungus Piriformospora indica on improving the grain related parameters of two native and improved rice cultivars under limited irrigation regimes

In order to evaluate the rol of mycorrhiza-like fungus Piriformospora indica on rice grain yield and water use efficiency under different limited irrigation regimes a field experiment was conducted in split factorial design with three replicates during 2014. Treatments were different irrigation methods at three levels (flooding, flooding after falling water depth less than 10 and 20 cm of soil surface) in main plot, two levels of P. indica inoculation (control and inoculation of six days old seedlings) and two rice cultivars (Tarom-Hashemi and Shiroudi) in sub plots as factorial. Results showed that maximum grain yield was obtained in Shiroudi cultivar in flooding (7801 kg/ha), followed by -10 and -20 cm irrigation regimes (5592 and 5575 kg/ha, resectively). This reduction in Tarom-Hashemi cultivar, however, was only significant where falling water depth was less than 20 cm of soil surface and yield loss was about 18 percent as compared to the flooding treatment. Nevertheless, P. indica inoculation in Shiroudi cultivar increased biological yield by 8 %, as compared to Tarom-Hashemi cultivar. Water use productivity and efficiency amounts in limited irrigation regimes was increased significantly in falling water depth less than 20 cm of soil surface treatment by 55 and 57 % , respectively as compared to flooding treatment. In conclusion, results represented a positive effect of coexistence between P. indica and rice plants particularly to ameliorate water deficit negative effects.