Evaluation of Streptomyces sp. obtained from herbal vermicompost for broad spectrum of plant growth-promoting activities in chickpea
Five strains of Streptomyces sp. (CAI-24, CAI-121, CAI-127, KAI-32, and KAI-90; demonstrated previously to have potential for control of Fusarium wilt disease in chickpea and plant growth promotion [PGP] in rice) were evaluated for their PGP capabilities in chickpea in the 2012–2013 and 2013–2014 post-rainy seasons. The plots inoculated with Streptomyces sp. significantly enhanced number of nodule, nodule weight, root weight, and shoot weight at 30 days after sowing (DAS) and number of pod, pod weight, leaf area, leaf weight, and stem weight at 60 DAS in both seasons over the un-inoculated control plots. At chickpea crop maturity, all of the Streptomyces strains significantly enhanced stover yield, grain yield, and total dry matter in both seasons over the un-inoculated control. In the rhizosphere, the Streptomyces strains also significantly enhanced soil biological and mineral nutrient activities including microbial biomass carbon, dehydrogenase activity, total nitrogen, available phosphorous, and organic carbon in both seasons over the un-inoculated control. All of the five strains were found superior in terms of nodule formation, root and shoot development, and crop productivity; however, KAI-xx had little edge over the other five strains. Scanning electron microscopy (SEM) analysis had revealed the success of colonization by the strains of Streptomyces sp. of the chickpea roots. Quantitative real-time PCR (qRT-PCR) analysis of selected PGP genes revealed overall upregulation of β-1,3-glucanase, indole-3-acetic acid, and siderophore genes in the Streptomyces species studied. This investigation further confirms the broad spectrum of PGP activities by the selected Streptomyces sp.
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