ISOLATION AND SELECTION OF PHOSPHATE-DISSOLVING BACTERIA FROM VEGETABLE SOIL AND THEIR EFFECT ON PLANT GROWTH PROMOTION IN WATER MORNING GLORY

Abstract

The study's objective was to isolate and select some bacterial strains able to resolve insoluble phosphorus and stimulate the growth of water spinach from vegetable soil in Tra Vinh province. First, we isolated 16 strains of bacteria able to resolve insoluble phosphorus with diverse colony morphology, including clear white, milky white, light yellow, and dark yellow. Then, we conducted qualitative phosphate solubilization by agar disc diffusion method with the resolved phosphorus ring diameter after five days ranging from 1.47 to 6.07 cm. Twelve strains of bacteria were selected after qualitative determination of soluble phosphorus by the molybdate method. The dissolved phosphorus content ranged from 6.76 to 48.61 mg/L after 10 days of inoculation. Four bacterial strains with the highest soluble phosphorus content, including P5, P8, P11, and P13, were selected to evaluate the effect on the germination rate and growth stimulation of water morning glory (Ipomoea aquatica) under laboratory conditions. The in vivo results showed that two isolate strains (P5 and P11) increased germination rate, stem height, root length, and fresh biomass. They had significant differences (p < 0.05) compared to the other strains. The 16S rRNA sequences showed that the two isolates, P5 and P11, were identified as Burkholderia spp.