Antifungal Activity and Phosphate Solubilizing Ability of Fungi Isolated from Rice Rhizosphere in Low Country Wet Zone of Sri Lanka

Abstract

Rhizosphere is the soil adjacent to plant root system and is a region with intense microbial activity. The role and importance of rhizosphere microorganisms in sustainable crop production have been reviewed by several researchers. Considering the negative impacts of agrochemicals, it is urgently needed to reduce the use of agrochemicals and use eco-friendly technologies to increase rice production. The objective of this study was to isolate fungi with antifungal activity and phosphate solubilizing ability from rice rhizosphere. In this study, fungi were isolated from rhizospheres of Bw 367, Bw 372 and Bw 272-6B rice varieties grown under drained and water logging conditions of paddy fields in the low country wet zone of Sri Lanka. The spread plate technique was used to isolate and purify all the isolates on Potato Dextrose Agar medium. A total of 41 and 32 fungal isolates were recorded in the rice rhizosphere under drained and water logging conditions, respectively. Antifungal activity of all the isolates was determined against Rhizoctonia solani, Bipolaris oryzae and Curvularia sp. using dual culture method. Two fungal isolates from rhizospheric soils of drained paddy field and three isolates from water logging paddy field showed more than 70% inhibition of the three pathogens by competition. All the isolates were screened for phosphate solubilisation on Pikovskaya’s agar medium and nine were identified as phosphate solubilisingO isolates. This study reveals that the rice rhizosphere is a rich source of fungi with antifungal activity and phosphate solubilizing ability.