Efficacy of Plant Growth Promoting Bacteria as Antagonists to Root Rot Pathogen in Sugarcane

Abstract

Fourteen plant growth promoting bacteria (PGPB), including 10 isolates of rhizospheric bacteria and 4 isolates of stalk endophytic bacteria were assessed for their ability to control root rot pathogen of sugarcane both in vitro and in vivo. These 14 PGPB were screened in vitro for their antifungal activity against Pythium sp. SD1/9-2, a causal agent of sugarcane root rot. Using dual culture technique, five PGPB isolates showed more than 25% inhibition of mycelial growth of Pythium sp. SD1/9-2. Based on results of in vitro screens, the five PGPB isolates, S65/4, 3/4, 30/1, 68/1 and 100/3 were evaluated further for efficacy under greenhouse conditions. As an indicator for controlling the root rot diseases for sugarcane, root fresh and dry weight of plant were measured and compared with the control plants. The result revealed that the maximum increase in root fresh and dry weight was observed in the sugarcane applied with the isolate 3/4 compared to the control inoculated plant with significant difference. At 30 DAI, root dry weight in the isolate 3/4 treatment were 38.3% higher than the control inoculated plant. This study suggested that the PGPB isolate 3/4 may be a potential biocontrol agent for sugarcane root rot disease under field conditions