EVALUATION OF PLANT GROWTH PROMOTING TRAITS OF AZOSPIRILLUM AND AZOTOBACTER SPP. ISOLATED FROM DIVERSE CROP AGRO- ECOSYSTEMS OF INDIA

Abstract

Plant growth promoting rhizobacteria sustains soil health by improving soil fertility. Many soil microorganisms are known to play a pivotal role in nutrient augmentation in plants, among them Azotobacter (AZB) andAzospirillum (ASP) are noteworthy plant growth promoters. In the present study 41 isolates of Azospirillumand 38 isolates of Azotobacter isolated from diverse crop production agro ecosystems of India were evaluated for plant growth promoting activity. These isolates were characterized for their ability to produce Hydrolytic enzymes, Exo-polysaccharide (EPS), Siderophores, Hydrogen cyanide, Ammonia, Auxins, Gibberellin’s and Biofilm. Test for production of hydrolytic enzymes indicated that 51.21% isolates of ASP were positive for cellulose and 31.7% isolates of ASP were positive for amylase, protease and pectinase. While 21%, 21.05% and 18.42% isolates of AZB were positive for cellulase, amylase, protease and pectinase respectively. Nine isolates ASPand ten isolates of AZB showed positive for chitin/chitosan modifying enzymes (CCME) 56% DA. When screened for EPS and biofilm production 78% isolates of ASP were positive for both EPS and biofilm. While 42% and 34.2% isolates of AZB were positive for EPs and biofilm respectively. Among all the isolates of Azospirillum 13, 19, 20, 32, and 35 andAzotobacter 2, 8, 10 and 17 were found positive for siderophores. Highest production of IAA was recorded in Azospirillum. Among all the isolates screened for production of ammonia,18 isolates of ASP and 7 isolates of AZB were strong NH3 producers. Six isolates of ASP (ASP 22, 25, 30, 33, 35, 36) and two isolates of AZB (ASP 20, 31) were strong producers of HCN. The promising isolates were further evaluated for invivo plant growth promotion.