Judul: Sunlight Use Efficiency by Sugarcane Crops On Various Level of Nitrogen and Phosphorus Fertilization
Abstrak: Light use efficiency is a crucial parameter in plant growth associated with accumulation of energy interception. Nitrogen and phosphorus deficiency can affect leaf area index (LAI) and specific leaf nitrogen and phosphorus (SLN and SLP) content resulting in reduction efficiency of light intercepted by plant canopy structure. This research was conducted in Kebun Bunga Mayang PTPN VII, North Lampung Regency, Lampung Province. Field observation is located on latitude of 04050’S and longitude of 104052’ E with elevation 38 meter from sea level which conducted from July 2008 to September 2009. Sugarcane was planted on August 20th 2008 and harvested on September 8th – 10th 2009. Treatments were distributed in the field under a randomized block design factorial with three replications. An increasing amount of nitrogen fertilizer (N) improved sunlight use efficiency by sugarcane crops. Fertilizing with 225 kg N ha-1 (489 kg Urea ha-1) on maximum stem phase (5 – 9 MAP) produced value sunlight use efficiency at 2.29 g MJ-1. An increasing efficiency value was linearly affected stem dry matter which is the major component in sugarcane production. On the contrary, the increasing of phosphor (P) fertilizer did not improve value sunlight use efficiency but affected stem dry matter on maximum seedling phase (3 MAP), maximum stem phase (9 MAP) and harvest phase (11 MAP) ; total dry matter on steady seedling phase (5 MAP) and maximum stem phase (9 MAP). Interaction between N and P were not increase value sunlight use efficiency by sugarcane crops. Thus only significantly affected dry matter of stem production on emergence phase (1 MAP) and steady seedling phase (5 MAP) ; total dry matter on emergence phase (1 MAP). A further research is still needed to conduct in order to investigate the amount of N doses level regarding on the improving value sunlight used efficiency due to its increasing level of N.
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Judul: Water use efficiency on upland sugar cane
Abstrak: Low Indonesian sugar production is mainly due to low productivity and low sugar yield. The shift of sugarcane crop acreage from low land to upland was the major factor of low productivity. Cultivation of sugarcane in uplands faced many constraints, namely low availaibility of soil water, low soil nutrient and unavailability of appropriate varieties. Cane cultivation in upland is commonly done at the beginning of the wet season (in November) in order to avoid the plant from water stress at the beginning of growth period. This causes the sugarcane age of only 7 months and have not reach maturity at harvest time in June which leads to lower sugarcane productivity. Shifting planting season is an alternative that can be done to obtain plants with sufficient maturity at the harvest time. However, the consequences of shifting the planting season is that the planting occured on dry season and which means that watering is needed. The limited availability of water demands efficiency in water usage. The application of organic matter as filter cake compost is expected to reduce the frequency of irrigation. This aims of this study are (1) to study the effect of water supply on performance of several varieties of sugarcane, (2) to study the effect of filter cake compost on nutrient uptake by sugarcane at various irrigation levels, (3) to analyze the efficiency of water usage in connection with the provision of filter cake compost in some varieties of sugarcane, and (4) to develop recommendation of water supply efficiency in the field with the addition of filter cake compost. The study was conducted in three stages of the experiment, which were the performance of several varieties under water stress, the effect of filter cake compost and irrigation on plant nutrient uptake, and the application of filter cake compost and frequency of irrigation on upland sugar cane productivity. The sugarcane varieties used in the experiments of performance varieties under different moisture content were PS 851, PS 864, PS 862, PS 921, PS 951, PS 91-787 and BL. After 3 months observation, it appears that water stress began significantly affected plant growth at 50% of field capacity (FC). The results showed that seven varieties were able to grow well under soil water content up to 75% FC. Based on Drought Tolerance Index, varieties BL and PS 864 has DTI values close to tolerant, while others were considered as moderate tolerant. Although the DTI value of PS 921 was only classified as moderately tolerant, it has the highest biomass in all of the soil water content treatments. It shows that PS 921 has the highest potential among the other varieties as variety of sugarcane suitable for upland planting. To study the effect of filter cake compost and water supply on the nutrient uptake of sugarcane, the variety PS 921 was used. The dose of filter cake compost were 0, 5, 10, 15, and 20 tons per hectare and the soil water content were 100%, 75% and 50% FC, respectively. The results of this experiments show that the uptake of P by sugarcane was influenced
Keyword: Water use efficiency, Saccharum officinarum L., Saccharrum robustum L.

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