Rice is a crop that requires high amount of water, and the drought is a major constraint in paddy cultivation. Water stress condition frequently prevails due to shortage of rain which results in significantly reduced plant growth and yield of rice. In the present study capability of Trichoderma spp. in imparting drought tolerance to rice, Oryza sativa was explored. Eleven local strains of Trichoderma spp. were applied to rice cv. Swarna Sub-1 through soil application (2 g/kg soil) and seed treatment (20 g/kg seed) under 0, 25, 50 and 75% less watering of the recommended amount. The soil application of T. harzianum AMUTHZ84 significantly promoted the shoot and root length (23.6 and 21.3%) followed by seed treatment (19.7 and 18.2%) under recommended level of irrigation condition (100% irrigation). Next in effectiveness was T. viride AMUTVR73 (21.5 and 18.1%) over untreated control. However, under 75% water availability, soil application with T. harzianum AMUTHZ82 was found superior over other isolates in enhancing shoot and root length (17.7 and 16.4%). The same isolate was also recorded to be superior under 50% (12.4 and 10.1%) and 25% water availability (9.3 and 8.1%) in enhancing the plant growth and biomass of rice cv. Swarna Sub-1. The isolate also significantly enhanced the leaf pigments, and photosynthesis in the rice plants grown under 25-75% water stress condition. In general, soil application of Trichoderma isolates was found more effective than seed treatment, and the T. harzianum AMUTHZ82 provided 8-17% enhancement in the plant growth, biomass, leaf pigments and photosynthesis of rice cv. Swarna Sub-1 grown under 25-75% water stress condition.
