AN ASSESSMENT OF PLANT GROWTH PROMOTING RHIZOBACTERIAL STRAINS FOR GROWTH OF SPINACIA OLERACEA UNDER IN-VIVO CONDITIONS

Plant growth promoting rhizobacteria (PGPR) are beneficial bacterial strains found in rhizosphere that colonize plant roots and enhances plant growth by wide mode of mechanisms. The usage of PGPR is increasing day by day in the field of agriculture and it offers a sensible way to replace chemical fertilizers, pesticides and other supplements. This preliminary study was carried-out to evaluate nine rhizobacterial strains associated with Spinacia oleracea for different plant growth parameters i.e. root length, shoot length, number of leaves and area of leaves, under in-vivo conditions. The tested rhizobacterial strains were isolated in a previous study from soil that had been cultivated with Spinacia oleracea for at least three consecutive seasons. This study is further extension of our work which involved the in-vitro analysis of the rhizobacterial strains for different plant growth promoting activities. All the tested rhizobacterial strains showed positive performance in terms of improvement in plant growth parameters when compared to that of control. Strains R13, R40, R50, and R53 showed best plant growth parameters under in-vivo conditions. Furthermore upon completion of one month, the shoot length of plants inoculated with isolate R13, R40, R50, R53 were found to be 32cm, 26.5cm, 34 cm, 38.6cm respectively, compared to control i.e. 21 cm, whereas root length of plants inoculated with same isolates were found to be 8cm, 15cm, 12.5cm, 8cm respectively, compared to control i.e. 9.5 cm. Number of leaves per plant, which were inoculated with these respective strain