Effect of Organic Compost, Tricalcium Phosphate and PGPB in Enhancing Growth and Glycoside Constituents in Four High Yielding Varities of Stevia Rebaudiana

A Phosphate solubilising bacteria (PSB), Curtobacterium agglomerans was isolated from rhizosphere of Stevia rebaudiana plants and tested positive for P-solubilization ability (285.0 µg ml−1 ug/ml), indole acetic acid (IAA) and siderophore production. The aim of this work was to evaluate the glycosides (Stevioside and Rebaudioside-A) status of four varities (GVS109, GVS16, GVS901, and GVS116) of Stevia differing in glycoside contents, when the above PSB and a nitrogen biofertilizer, Azotobacter chroococcum, enriched organic compost and tricalcium phosphate (TCP) were applied. The results showed that in comparison to control, inoculation with C. agglomerans, significantly increased shoot biomass as well as steviol glycoside, and NP content in plants. However, such increased effects have been found to be further enhanced significantly due to dual inoculation (C. agglomerans + A. chroococcum) in TCP amended soils enriched with compost. The results of this study suggest that C. agglomerans alone or in combination with A. chroococcum have the potential to increase the growth and glycoside contents of Stevia high yielding plant varities under organic growing conditions and TCP amended soil.