Abstract:
Acinetobacter calcoaceticus, a plant growth promoting rhizobacteria (PGPR) and gibberellins producing strain was investigated for the presence of organic acids in its culture and interactive effect on cucumber plant’s growth, phytohormonal levels and functional biochemicals. A. calcoaceticus culture’s analysis showed the presence of three organic acids viz. malic, succinic and citric acids. The quantity of malic acid was significantly high compared to succinic and citric acids. Besides that, the free phosphate level was highest at the fifth day of bacterial culture growth. In A. calcoaceticus and plant’s association experiment, the strain has significantly ameliorated cucumber plants to higher growth. The PGPR culture application had higher shoot length; plant biomass and chlorophyll contents compared to controls (distill water-DW and nutrient broth-NB). The bacterial culture treated plants has higher amino acid and crude protein contents compared DW and NB. In amino acid analysis, threonine, alanine and proline quantities were significantly higher in PGPR treated plants than control plants. A. calcoaceticus treated plants had low endogenous abscisic acid contents but contrarily higher GAs (GA1, GA4, GA9 and GA20) compared to controls (DW and NB). The PGPR has activated the GAs biosynthesis pathway while promoting the cucumber plant’s growth. Application of such eco-friendly PGPR can be a viable alternative to synthetic fertilizers.
