Judul: Growth, shoot production, and metabolite content of waterleaf (talinum triangulare (jacq.) willd) with repeated organic fertilization.
Abstrak: Waterleaf (Talinum triangulare (Jacq.) Willd) can be consumed as vegetable by consuming its shoot. Waterleaf is known as functional vegetable because the shoot contains some bioactive compounds to maintain human health. The purpose of this research was to investigate the effect of organic fertilizer combination to growth, production and metabolite content of waterleaf i.e. vitamin C, flavonoid, and peroxidase (POD) activity in the first and second planting season and organic fertilizer residue with repeated harvesting. This research was conducted at Leuwikopo Darmaga Bogor and Plant Analysis and Chromatography Laboratory, Department of Agronomy and Horticulture, IPB in November 2012-May 2013. The organic fertilizers were cow manure (CM), rock phosphate (RP) and rice-hull ash (HA). The fertilizer was combined into four combinations, CM + RP, CM + HA, RP +HA, and CM +RP +HA; with one control (without fertilizer). Treatment was arranged with randomized completely block design with three replications. Two experiments were set in the second season, i.e. the effect of organic fertilizing in the second season and the effect of organic fertilizer residue. The result showed that organic fertilizer gave same effect on growth, shoot production and metabolite content of waterleaf. Vitamin C was positively correlated to flavonoid content while flavonoid and vitamin C content was negatively correlated to K. Low rain intensity in the second harvest increased POD activity while flavonoid content decreased that was caused by precursor competition in flavonoid and lignin biosynthesis. Lignin biosynthesis is catalyzed by POD enzyme. Application of organic fertilizer in the second season increased growth, production, and metabolite content of waterleaf shoot. Cow manure + rock phosphate + rice-hull ash treatment gave the highest increase of shoot production compared to control treatment. Organic fertilizer residue from first season gave the same effect on growth and shoot production compared to control treatment. There was no significant difference effect between residual effect and organic fertilizer added in the second season. Growth and shoot production in the second season was lower than first season that was caused by low of rain intensity that inhibited the growth of waterleaf. The same condition also occurred in waterleaf metabolite content. Vitamin C content decreased in the second season while flavonoid content increased.
Keyword: flavonoid, POD, repeated harvesting, Talinum triangulare, vitamin C

Judul: Waterleaf production and quality with organic and inorganic fertilizer
Abstrak: Three consecutive field experiments had been conducted at the IPB experimental station (Bogor, Indonesia), in March-July 2011 to study the effect of two types of fertilizer on waterleaf [Talinum triangulare (Jacq.) Willd.] production and quality in wet (March-May 2011) and dry (May-July 2011) seasons; while laboratory analysis was conducted from April to December 2011. The first experiment was in wet season and consisted of two sets of treatment, namely different rates of organic [cow manure (ton/ha) + guano (kg/ha) + hull ash (ton/ha), i.e. 6.1 + 75.6 + 2.7, 9.2 + 151.2 + 4.1, 12.3 + 226.8 + 5.5, 15.4 + 302.4 + 6.8, and 18.4 + 378.0 + 8.2] and inorganic [urea (kg/ha) + SP-36 (kg/ha) + KCl (kg/ha), i.e. 50 + 20 + 50, 75 + 40 + 75, 100 + 60 + 100, 125 + 80 + 125, and 150 + 100 + 150] fertilizer. The second experiment was in dry season and consisted of two sets of treatment, namely different rates of organic and inorganic fertilizer (same as the first experiment). The third experiment was in dry season and consisted of four sets of treatment, namely different rates of organic (6.1 + 75.6 + 2.7, 12.3 + 226.8 + 5.5, and 18.4 + 378.0 + 8.2; the fertilizers and units were as above) and inorganic (50 + 20 + 50, 100 + 60 + 100, and 150 + 100 + 150; the fertilizers and units were as above) fertilizer, and organic and inorganic fertilizer residue (without fertilizer re-application). The experimental design for each set was randomized block design. Since fertilizer rates did not significantly affect the variables, means value of each set were compared by using t-student’s test. Generally, the result from these research suggested that (1) In wet season, waterleaf with organic fertilizer did not have any difference in shoot production; while in dry season, these treatments resulted in higher shoot production compared to those with inorganic fertilizer; (2) Waterleaf antioxidant capacity of organic and inorganic treatments were not significantly different in the same planting season; (3) The primary (vitamin C) and secondary (flavonoid) metabolites with antioxidant functions were higher in dry season compared to those in wet season; (4) Biosynthesis pathway of waterleaf phenolic compounds in wet season was different from that in dry season. It was suspected that phenolic compounds were synthesized predominantly via phenylpropanoid pathway in wet season and via acetate-malonate pathway in dry season; (5) Without organic or inorganic fertilizer re-application in the new planting season, yield of waterleaf shoot decreased approximately 26-50 % but did not degrade the quality.
Keyword: 

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