Judul: Physiological adaptation of Sorgum (Sorghum bicolor (L.) Moench) to aluminum toxicity and phosphorous deficiency in acid soils.
Abstrak: Sorghum (Sorghum bicolor (L) Moench) is an ideal crop to be developed as food diversification and source of bioethanol in Indonesia because this crop has high adaptability to be grown in dry lands. From a total of 148.2 millions ha dry land in Indonesia, an estimated are of 108 millions ha are acid soil (ultisols). Acid soils have low fertility and Al toxicity which are major constraints for crop production in acid soil. For sorghum production in acid dry lands, sorghum varieties having high adaptation to acid soil have to be developed. The objectives of this study was to obtain complete information about the physiological adaptation to aluminum toxicity and phosphorus deficiency which can be used as the character selection in breeding program to obtain the tolerant sorghum in acid soils. The genotypes used was Numbu (Tolerant), ZH-30-29-07 (Tolerant), B-69 (sensitive) and B-75 (sensitive) from selected on acid soils in Lampung. The study on physiological mechanism of sorghum adaptation to acid soils has resulted in information that the main limiting factor in soghum growth in acid soil was phosphorous deficiency. Under sufficient P, without liming, the sensitive genotype produced similar yield. The tolerant genotype, Numbu and ZH30-29-07 showed higher ability to maintain root growth under Al stress and P deficiency. The tolerant genotypes also showed higher ability to absorp nutient under low P condition compared to sensitive genotypes. The lowest concentration of 74 μM Al can reduce the growth in all genotypes tested. The longer the sorghum roots exposed to the stress, the higher the value of scoring and the accumulation of aluminum in the roots under Al toxicity. Sorghum genotypes had specific absorption rate was high, but it was not followed by increasing of roots length, roots dry weight and shoot dry weight. Specific absorption rate is more affected by Al stress rather than increasing level of P. Genotype ZH-30-29-07 were tolerant in identified in acid soils showed the moderate response to Al toxicity in nutrient solution. The higher aluminum concentration leading to greater plant growth inhibition. The tolerant genotypes had the internal mechanism (tolerance) in the face under low P condition by increasing the efficiency of internal phosphor (interrelated), otherwise the sensitive genotype had the external mechanism (avoidance) through increased P absorption or total P . There was no relationship between the use efficiency of P with total P content of plant both in testing using the acid soils in rhizotron and nutrient solution.
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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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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