Pelarutan Batuan Fosfat oleh Bakteri Pelarut Fosfat dan Kemampuannya dalam Meningkatkan Pertumbuhan Tanaman Sengon Buto (Enterolobium cyclocarpum)

Nine isolates of phosphate solubilizing bacteria isolated from rhizosphere soil were investigated for their ability to solubilize rock phosphate in vitro. All of isolates tested showed the ability to solubilize rock phosphate in both solid and liquid medium. The solubilization in solid medium showing the formation of visible dissolution halos on agar plate with solubilization efficiency ranged from 128 – 216. The solubilization of rock phosphate ranged from 2.53 mg.l-1 – 5.61 mg.l-1 in liquid medium. Pot culture with nine isolates using Sengon buto (Enterolobium cyclocarpum) as the test plant and rock phosphate as the phosphorus source was conducted at green house of Microbiolgy Division, Research Center of Biology, Indonesian Institute of sciences, Cibinong. Experiment laid out as factorial based on randomized complete design with tree replication. Two levels of rock phosphate fertilizer consisted of 50 kg ha-1 and 100 kg ha-1 and ten levels of isolates (consisted of Control without inoculation, T,Y,C,W,E,J,L,S and O isolates) were treatments. The result showed significantly increased growth of Enterolobium cyclocarpum seedling compared with the uninoculated control. Total culturable phosphate solubilizing bacteria count increased by inoculation. The phosphomonoesterase, the available P contents of the soil were stimulated by the inoculation with the phosphate solubilizing bacteria. Among the isolates best effect on yield was obtained with E isolat. Jurnal Teknologi Lingkungan, Edisi Khusus “Hari Bumi”. Hal. 21-29 ISSN 1441-318X