Aktivitas Pelarutan Fosfat Organik Dan Anorganik Oleh Bakteri Pelarut Fosfat In Vitro Dan Pengaruhnya Terhadap Pertumbuhan Seedling Sorghum Bicolor

The production of phosphatease enzyme and organic acid plays important role in the process of organic and inorganic phosphatee dissolution by phosphatee solvent bacteria so that the phosphatee is available for the plants. This study aimed to discover potential isolate in dissolving phosphatee and being able to be used as biofertilizer. In this study isolation and selection of 15 phosphatee solvent bacteria has been done to analyze its ability to dissolving organic and inorganic phosphatee. The activity of organic phosphatee dissolution is measured by measuring phosphatease enzyme produced from p-nitrophenol phosphatee as the substrate (raw material). While the activity of inorganic phosphatee dissolution is measured by measuring the concentration of dissolved phosphatee in Pikovskaya medium which is containing Ca3(PO4)2 as the source of phosphatee. The selected isolate of phosphatee solvent bacteria (PSB) then used as inoculant in seedling growth of sorghum bicolor in green house scale. The experiment used Completely Randomized Design (RCD) in factorial pattern with three replications. First treatment is sterilized soil (S) and non-sterilized soil (NS). Second treatment is plant control without inoculant (K), fertilizer (P), fertilizer and dual inoculant (PC), inoculant phosphatee solvent bacteria (PSB), vesicular arbuscular mycorrhizae/VAM (M). The result showed that all isolate tested of phosphatee solvent bacteria could produce acid and alkaline phosphatease in the range of 0.07 – 0.43 µg pNP/ml/hour and 0.24-0.45 µg pNP/ml/hour. Same goes to dissolved phosphatee which is varied between 6.35-11.19 ppm with the decrease of pH of 3.84 – 5.66. Sole application of either PSB inoculant or VAM could increase the growth of seedling sorgum for about 40-46 persen compared to control without inoculant on both of soil. While dual inoculation of PSB and VAM with fertilizer phosphate as 25 persen better than dual inoculation without phosphatee fertilizer and 76 persen compared to control. Proseding Seminar Nasional, Jakarta, 8 Februari 2017