Biocontrol of sheath blight on rice and growth promotion by Trichoderma isolates from the Amazon

Abstract

This investigation was made to select Trichoderma isolates from Amazon forest soil samples and identify their potential for sheath blight (Rhizoctonia solani) suppression in rice and plant growth promotion. Four (T.06, T.09, T.12, T.52) out of 13 isolates which showed potential  in vitro evaluation were assayed under greenhouse conditions using four application methods: 1) preventive and curative sprays; 2) seed treatment + curative sprays; 3) seed treatment; 4) substrate treatment. These four isolates also showed reduced R. solani mycelial growth and sclerotial viability (> 50%); positive for phosphate solubilization and cellulose degradation. They significantly reduced sheath blight severity when applied as seed treatment, substrate incorporation or as foliar spray. However, the curative and preventive spray was efficient in reducing sheath blight severity by 43% and area under the disease progress curve by 65% and was found to be the best method. Isolates T.12 and T.52 in the substrate treatment increased aerial part and root dry weight by 61.2 and 32.9%, respectively.These two isolates which showed potential as growth stimulants can be used as novel biological products and as bioinoculants in agriculture for increasing grain yield.