LAPORAN AKHIR PENELITIAN UNGGULAN PERGURUAN TINGGI PEMANFAATAN INOKULASI GANDA BAKTERI PELARUT FOSFAT DAN PELARUT KALIUM PADA MEDIA BAGASE TEBU GUNA PENINGKATAN KETERSEDIAAN HARA TANAH DAN PERTUMBUHAN TANAMAN

Abstract

Potassium solubillizing microorganisms (KSM) and phosphate solubillizing microorganisms (PSM) isolated from sugarcane rhizosphere and their capability on solubilization from some insoluble potassium and insoluble phosphate were examined. Isolation of microorganisms was carried out from three sugarcane plantations area, on Aleksandrov’sand Pikovskayaagar medium. From the 41 isolated microorganisms were selected 15 isolates potassium solubilizing microorganisms which exhibiting highest potassium solubilization (solubility index) on solid medium. All the KSM were found to be capable of solubilizing K from insoluble K-bearing minerals source, and the solubilization zone ranging from 0.15 to 4.5 cm. 13.3% isolate has Solubility Index (SI) more than four on solid medium. Quantitative test result of KSM conducted on liquid medium containing potassium mineral trachyte, feldspar, leucite (Pati and Situbondo), released water soluble-K (exchangeable-K) ranging from 0.13 to 12.25 mg.L-1 (Feldspar); 1.24 to 15.57 mg L-1 (Leucite pati); 1.01 to 4.,59 mg L-1 (Leucite Situbondo); and 0.16 to 6,34 mg L-1 (Trachyte). KSM strain Sbr3caused maximum solubilization on feldspar (12.25 mg L-1), KSM strain Asb3 on leucite Pati (18.17 mg L-1), KSM strain Prj3 on leucite Situbondo (16.14 mg L-1), whereas KSM strain Prj5 caused maximum solubilization on trachyte (6.92 mg L-1).All isolates produce organic acid citric, ferulic and coumaric, some isolates also produce malic and syringic acid. Total organic acid produced by isolated ranging from 130.42to 434.44 mg.L-1. Ferulic acid was produced by all isolates on all of K sources higher than other organic acid.