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Stimulatory effect of phosphate-solubilizing bacteria on plant growth, stevioside and rebaudioside-A contents of Stevia rebaudiana Bertoni

Mamta, Rahi, Praveen, Pathania, Vijaylata, Gulati, Arvind, Singh, Bikram, Bhanwra, Ravinder Kumar, Tewari, Rupinder
Applied soil ecology 2010 v.46 no.2 pp. 222-229
Stevia rebaudiana, nonnutritive sweeteners, soil bacteria, Burkholderia gladioli, Enterobacter aerogenes, Serratia marcescens, phosphorus, soil fertility, nutrient availability, microbial genetics, ribosomal RNA, glycosides, stevioside, phytochemicals, tricalcium phosphate, fertilizers, fertilizer rates, rhizosphere bacteria, indole acetic acid, siderophores, plant growth, microbial colonization, roots
The effect of four phosphate-solubilizing bacteria (PSB), (Burkholderia gladioli 10216, Burkholderia gladioli 10217, Enterobacter aerogenes 10208 and Serratia marcescens 10238) as identified on the basis of 16S rRNA gene sequencing was evaluated on plant growth and commercially important glycosides, stevioside (ST) and rebaudioside-A (R-A) of Stevia rebaudiana in pots containing tricalcium phosphate (TCP) supplemented soil. The PSB were isolated from the rhizosphere of S. rebaudiana plants and tested for P-solubilization ability, biocompatibility, indole acetic acid (IAA) and siderophore production. In greenhouse study, treatment of either individual PSB or a consortium (of PSB) resulted in increased plant growth, ST and R-A contents. The stimulatory effect was observed with consortium treatment in plant growth parameters (shoot length, 22.5%; root length, 14.7%; leaf dry weight, 89.0%; stem dry weight, 76.3% and shoot biomass, 82.5%) and glycoside contents (ST, 150% plant⁻¹ and R-A, 555% plant⁻¹) as compared to the un-inoculated plants. Among individual PSB treatments, B. gladioli 10216 showed most promising response in majority of the parameters studied. The root colonization potential of PSB, assayed by RAPD technique, showed the colonization of all PSB isolates, though their extent of colonization varied.