Efektivitas Mikrob Pelarut Fosfat dalam Meningkatkan Kelarutan Fosfat Alam dan Memperbaiki Pertumbuhan Sorgum Manis (Sorghum bicolor (L.) Moench).

Abstract

Phospate solubilizing microbes (PSM) is the microbe which have ability to solubilize less soluble phospate, so that phospate available to plant growth. To obtain an effective microbe, a series of selection are required. This research started from isolation phospate solubilizing microbe and testing the ability to solubilize less soluble phospate in laboratory, green house or field. The objective of this research was to isolate and select the phospate solubilizing microbes consisted of phospate solubilizing bacteria and phospate solubilizing fungi. The ability of phospate solubilizing microbes was tested in three less soluble P sources which are Ca3(PO4)2, phospate rock Ciamis, and AlPO4. Phospate solubilizing microbes were isolated from the cocoa root located in Gangking, Ujung Bulu, and Rilau Ale District, Bulukumba, South Sulawesi. A total of 115 isolates were isolated and purified, then as many as 39 isolates were tested qualitatively to see the ability to solubilize less soluble phospate. After the qualitative, from 39 isolates selected 19 isolates consisting of 15 bacterias and four fungis were tested in quantitative test the ability to solubilize less soluble phospate. Quantitative test results showed that phospate solubilizing microbes had vary ability depending on source of less soluble phospate. Isolate bacteria SS1.2 had highest ability to solubilize phospate rock Ciamis, but the ability to solubilize Ca3(PO4)2 included moderate, and solubilize AlPO4 included low. Based on quantitative test results, were selected two phospate solubilizing bacterias and two phospate solubilizing fungis to be tested the ability of phospate solubilizing microbe to enhance the growth of sweet sorghum in greenhouse. Phospate solubilizing microbes consisted of two phospate solubilizing bacterias and two phospate solubilizing fungis as the first factor and P fertilizers as second factor consisted of without P, phospate rock Ciamis 50 ppm P and SP-36 50 ppm P in Ultisol. The growth of sweet sorghum was not normal, after eight weeks the plant’s height only 32.40 cm. This was due to the Al dd very high disruptive root and plant growth overall, so that the influence of phospate solubilizing mirobe to the plant growth could not be evaluated.