Judul: Efektivitas Mikrob Pelarut Fosfat dalam Meningkatkan Kelarutan Fosfat Alam dan Memperbaiki Pertumbuhan Sorgum Manis (Sorghum bicolor (L.) Moench).
Abstrak: 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.
Keyword: less soluble P, phospate solubilizing bacteria, phospate solubilizing fungi

Judul: Studi Mikrob Pelarut Fosfat untuk Mengurangi Dosis Pupuk P Anorganik pada Sistem Budidaya Padi Pengelolaan Tanaman Terpadu (PTT) dan System of Rice Intensification (SRI)
Abstrak: Phosphorus (P) fertilizer has an important role in increasing the production of paddy rice (Oryza sativa L.). Application of high rate P fertilizer is not suitable with the availability of P in the soil because most P bounded by Al, Fe and Ca so make it unavailable to plants. This leads to inefficient use of P fertilizers. Utilization of phosphate solubilizing microbes (PSM) is one of the means to increase the availability of P that can be absorbed by plants, thus reducing the use of inorganic-P fertilizer. Therefore, the aims of the experiment were (1) isolating and selecting some phosphate solubilizing microbes, (2 )to test its effectiveness of PSM in increasing the availability P available on cultivation system of ICM and SRI, (3) to know the effect of PSM to reducing rate inorganic-P fertilizer on the growth and yield of rice. The experiment was conducted of two experiment. First experiment was conducted in Soil Biotechnology Laboratory, Department of Soil Science and Land Resources, Faculty of Agriculture, Bogor Agricultural University in October 2011 - April 2012. Second experiment was conducted at Field Experiment Sawah Baru, University Farm, Bogor Agricultural University in May to August 2012. The first experiment was (1) isolating and selecting PSM (phosphate solubilizing bacteria and fungi) from biofertilizers. (2) Phosphate solubilizing index test (PSI) to measure the clear zone around the colony. (3) Test the ability of solubilizing P from insoluble phosphate source (Ca3(PO4)2, AlPO4, FePO4). (4) Antagonistic test to know ability of phosphate solubilizing bacteria and fungi and compatibility both in the growing medium and identified of phosphate solubilizing bacteria and fungi. The second experiment was conducted using a split block design with two factors and three replications. First factor as main factor is cultivations system (ICM and SRI) and second factor as sub plot is Combination of rate inorganic-P fertilizer and PSM namely 100% inorganic-P; 75% inorgaic-P; 75% inorganic-P + Phosphate solubilizing bacteria (PSB); 75% inorganic-P + phosphate solubilizing fungi (PSF); 50% inorgaic-P; 50% inorganic-P + PSB; 50% inorganic-P + PSF; PSB only; PSF only; and PSB + PSF. The results of laboratory experiment obtained isolate of PSB BPFA5 (Pseudomonas aeruginosa) and the isolate of PSF FPFE1 (Aspergillus niger) has high phosphate solubilizing index, with wide of clear zone is 2.29 and 1.22, ability of phosphate solubilizing from P source Ca3(PO4)2 is 259.86 dan 537.26 ppm-P and compatible (non antagonistic) in same medium. Both of these isolates used for inoculation in the field. The result of second experiment in the field showed that treatment of cultivation system produced that number productive of tillers, weight of dry plant ,number of grain per panicle, weight of 1000 grain, yield, and population of phosphate solubilizing microbes higher on SRI cultivation system than ICM cultivation system. Combination of 75% inorganic-P fertilizer + PSM on SRI cultivation system produced number of productive tillers, yield, and uptake P of viii grain higher than other treatments. PSM application (PSB and PSF) increase of yield and nutrient-P uptake of straw and grain.
Keyword: integrated crop management (ICM), phosphate solubilizing bacteria, phosphate solubilizing, fungi, system of rice intensification (SRI)

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
Keyword: