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: 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: 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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