Application of ready-to-use dry-powder formulation of Talaromyces flavus Bodhi001 against rice brown leaf spot disease and to promote the yield components of rice in saline-alkaline soils

Abstract

Rice brown leaf spot disease caused by Bipolaris oryzae and saline- alkaline soils are serious constraints on rice production causing both qualitative and quantitative yield losses. Ready-to-use dry powder formulations of the antagonistic fungi Talaromyces flavus Bodhi001, Talaromyces trachyspermus Bodhi002, Talaromyces flavus Bodhi003, and Neosartorya fischeri Bodhi004 were developed by heat-drying in a hot-air oven at 75 °C for 6 h and subsequent grind them into a fine powder. Dry formulations were evaluated both for their biocontrol activity of rice brown leaf spot disease and for their contribution to rice growth in saline-alkaline soils under greenhouse conditions. The results showed that the dry formulation of T. flavus Bodhi001 achieved the most significant reduction in disease incidenceand demonstrated a substantial disease reduction compared to the control treatment. The dry formulation of N. fischeri Bodhi004, gave a somewhat smaller disease reduction when applied twice the vegetative and flowering stages. Meanwhile, in vitro tests of T. flavus Bodhi001 also induced IAA production and phosphate solubilizing activities in the culture medium. The application of the dry formation of T. flavus Bodhi001 at 100 g /5 kg of soil resulted in the highest tiller number per plant and a significantly higher 1,000 grain weight, followed by the dry formulation of N. fischeri Bodhi004 at under saline-alkaline stress conditions also presenting the highest tiller number per plant and a significantly higher 1,000 grain weight at 22.15 g. The results indicate that the ready-to-use dry-powder formulation of T. flavus Bodhi001 is an effective biocontrol agent against rice brown leaf spot disease and that it promotes yield components of rice in saline-alkaline soils.