Effect of fungus Piriformospora indica on the grain yield, absorption and radiation use efficiency of millet under different irrigation regimes

To investigate the effect of Piriformospora indica fungus on absorption and radiation use efficiency of millet under water stress, an experiment was carried out as a split plot in randomized complete block design with three replications in research field of Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran, during 2014 and 2015. The main factor was irrigation in three levels (irrigation after 60, 90 and 120 mm evaporation from pan class A) and sub factor was in two levels of fungus P. indica (inoculated and non-inoculated). In the both years, water stress decreased leaf area and dry matter accumulation of millet. Inoculation with fungus, increased leaf area and dry matter of millet plants in different irrigation levels. The highest radiation use efficiency (2.31 and 2.53 g.MJ-1 in 1st and 2nd years, respectively) was obtained in inoculated millet plants under well-watered, and the lowest (1.96 and 2.08 g.MJ-1 in 1st and 2nd years, respectively) was observed in non-inoculated plants under severe water stress. Severe water stress significantly decreased grain yield of millet in both 1st and 2nd years about 57.53 and 46.91 percent, respectively. Under severe water stress, inoculating increased grain yield by 35.34 and 32.50 percent in 1st and 2nd years, respectively, compared to control (non-inoculated). The results showed P. indica fungus, had a positive effect on absorption and radiation use efficiency of millet in different irrigation levels, so that the application of fungus mitigated the effects of water stress and improved the yield of millet under water stress.