Synergistic Test and Bioassay of Phosphate Solubilizing Bacteria for Improving Growth of Rice Seedling

. The increasing of conventional productivity still depends on inorganic fertilizers. The use of inorganic fertilizers continuously decreases the soil quality. One of the problems encountered is the low availability of soil P. One of the efforts to increase the availability of P in the soil is by using Phosphate Solubilizing Bacteria (PSB). This research aims to study the synergistic test between PSB and determine PSB isolates which can increase the rice growth in bioassay experiment. This experiment consisted of 2 stages, the synergistic test which was carried out in the Laboratory of Soil Biology and bioassay experiment in the Greenhouse, Department of Soil Science and Land Resources, Faculty of Agriculture, Universitas Padjadjaran from August to September 2020. The bioassay experimental design that we use was randomized block design (RBD) with 6 treatments and 5 replications. Each type of bacterial treatment was control, Burkholderia sp., Pseudomonas mallei, Bacillus substilis, Bacillus megatherium and mixed isolates. The data obtained showed that each PSB isolates were compatible with each other. The result showed that mixed PSB treatment improved rice growth.