Judul: Regulasi Etilen dalam Respon Tanaman Sorgum [Sorghum bicolor (L.) Moench.] terhadap Cekaman Defisiensi P dan Toksisitas Al
Abstrak: Understanding the tolerance mechanism of sorghum [Sorghum bicolor (L.) Moench] to aluminium (Al) toxicity and phosphorus (P) deficiency is of high importance to assists breeding program of acid soil-tolerant sorghum. The objective of this research was to study the role of ethylene in the response of sorghum to Al toxicity and P deficiency. This research was conducted in Cikabayan Experimental Field from March to June 2013. This research consisted of two experiments. The first experiment was aimed to determine etephon concentration that could distinguished Al accumulation in the root of Numbu (toleran) and B69 (sensitive) genotypes by haematoxylin staining. The Numbu and B69 seedlings were grown hydroponically for two days in the nutrient solutions containing 0 and 74 μM AlCl3, and different levels of etephon concentrations (i.e. 0, 12.5, 25 and 50 ppm). The first experiment result showed that under 74 μM AlCl3, 12.5 ppm etephon could distinguished the Al accumulation in Numbu and B69 root tip. The second experiment was arranged in randomized completely block design with two factors and three replications. The first factor was P availability and Al toxicity, consisted of four levels i.e. low-P (0.001 mM KH2PO4), sufficient-P (0.1 mM KH2PO4), low-P + 74 μM AlCl3, and sufficient-P +74 μM AlCl3. The second factor was the exogenous application of ethylene regulator, consisted of three levels i.e. control (without ethylene regulator), ethylene precursor (12.5 ppm ethepon), and ethylene action inhibitor (0.6 μM AgNO3). Two sorghum genotypes (Numbu and B69) were grown hydroponically for 14 days. The results showed that Numbu, the acid soil tolerant genotype, was less affected by the P-availability and Al toxicity. In contrast, low-P and Al toxicity significantly decreased root- and shoot length, and shoot- and root-fresh weight of B69, the acid soil sensitive genotype. Application of exogenous ethylene significantly decreased root length, while application of ethylene action inhibitor significantly increase root length in Numbu genotype but not in B69 genotype, indicating that Numbu was more responsive to ethylene. Inhibition of ethylene action under low-P and Al toxicity caused growth inhibition in B69 genotype. Taken together our results imply that the different tolerance to acid soil of Numbu and B69 genotype might be caused by the different responsiveness to ethylene.
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Judul: Response of sorghum [Sorghum bicolor (L.) Moench] genotypes to phosphorus fertilizer in different aluminum saturation Levels in Acid Soil.
Abstrak: Sorghum is one of high value commodity for food and energy security. Sorghum can solve food and energy crisis integratedly in one time and space. Sorghum also can increase productivity of marginal land because sorghum is a drought tolerant crop and suitable to be developed in Indonesia uplands. The major problem of uplands in Indonesia is predominance of acid soil with Al toxicity. The objective of this research was to obtain information about differential response of sorghum genotype tolerant and sensitive aluminum to phosphorus fertilizer in different aluminum saturation levels in acid soil. This research consisted of two stages, i.e: (1) evaluation of differential response of sorghum genotype tolerant and sensitive aluminum to phosphorus fertilizer in different aluminum saturation levels in acid soil, (2) evaluation of growth and development response of sorghum root to phosphorus fertilizer in different aluminum saturation levels in rhizotrone. Evaluation of differential response of sorghum genotype tolerant and sensitive aluminum to phosphorus fertilizer on different aluminum saturation levels in acid soil was conducted in split plot design in Tenjo, Jasinga. Rhizotrone research was conducted in split plot design in greenhouse at University Farm, IPB, Bogor. Aluminum saturation level as a main plot was 2 levels: high level of aluminum saturation (74.78%) and low level of aluminum saturation (25.51%). Four genotytpes were evaluated in this research as sub-plot: Numbu (tolerant), Kawali (tolerant), B-69 (sensitive), and B-75 (sensitive). Phosphorus fertilizer was given into 4 doses as main-plot : P-25%, P-50%, P- 75%, and P-100%. The results from stage one showed that there were different response of each genotype to phosphorus fertilizer in different aluminum saturation levels in acid soil. Numbu has highest value for each variable on this research. On high level of aluminum saturation, P fertilizer didn’t effect to almost variable on this research except sugar level of stem in B-69. On low level of aluminum saturation, P fertilizer effect penicle weight, grain per penicle weight, total weight, and stem weight in B-69. On rhizotrone research, P fertilizer effect root dry weight and root wet weight in B-69 on low level aluminum saturation.
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix