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Biological control of sugarcane red rot pathogen Colletotrichum falcatum by native rhizospheric bacteria

Prittesh Patel: C G Bhakta Institute of Biotechnology, Uka Tarsadia University

<div>Red rot, caused by <em>Colletotrichum falcatum</em> is a severe disease of sugarcane. To develop a new biocontrol product we collected 226 rhizobacteria from the six sugarcane variety and screened against three pathogenic <em>Colletotrichum falcatum</em> strains, namely cfNAV, cfCHA and cf8436. Accordingly best five antagonistic rhizobacteria were chosen for further <em>in vitro</em> assay by dual culture technique on PDA and <em>in vivo </em>assay by pot trial on highly susceptible sugarcaane variety CoC 671 under green house conditions for 60 days. Sugarcane plants without any microbial treatment were served as control. All five isolates were characterized for biochemical and plant growth promoting activities such as IAA production, Phosphate mobilization, Nitrogen fixation and siderophore production. Molecular identification by 16S rRNA gene sequencing reveals five strains as <em>Ochrobactrum intermedium</em> TRD14<em>; Acinetobacter sp</em> PK9<em>;</em> <em>Bacilli sp</em> RSC29<em>; Bacillus sp</em> KR91 and<em> Escherichia sp</em> VRE34<em>.</em> In dual culture assay <em>Acinetobacter sp</em> PK9 gave maximum 71.64±1.34% inhibition against cfCHA followed by <em>Escherichia sp </em>VRE34 against cfNAV (60.44±2.38%). In pot trail, sugarcane plants separately inoculated with each pathogen were died within one month while co-inoculation of each antagonist protected the plant for two month and also supported good growth. In case of <em>Escherichia sp </em>VRE34 treatment, plant height and stem diameter were increased from 13.27±0.67 inches to 24.03±1.40 inches and 6.07±0.45 mm to 9.87±0.93 mm respectively. All the five isolates have shown antagonistic activity and in both <em>in vitro</em> and <em>in vivo</em> conditions. In conclusion, mentioned isolates with potential to suppress red rot pathogen efficiently and growth promotion in sugarcane can be use for making biofertilizer/biopesticide against red rot disease for sustainable agriculture.</div>