INDONESIAN JOURNAL OF AGRICULTURAL SCIENCE

47-54

Authors: A. Wihardjaka, S. Djalal Tandjung, B. Hendro Sunarminto, Eko Sugiharto

Rice cultivation is one of the antropogenic sources of nitrous oxide (N2O) emission that is produced by microbiological nitrification-denitrification processes. Incorporating soil amendment in rainfed rice soil attempted to increase soil productivity, while nematicide application aimed to maintain root growth system. Incorporating soil amendment and nematicide application are predicted to suppress N2O production in lowland rice. The objective of this research was to study the interaction of soil organic amendment and nematicide on N2O emission and nitrogen uptake from rainfed lowland rice soils. A field experiment was conducted in rainfed lowland rice soils during 2010/2011 wet season (direct seeded rice) and 2011 dry season (transplanted rice). The 3 x 3 factorial trial was arranged in a randomized completely block design with three replications. The first factor was soil amendment consisted of without rice straw, fresh rice straw and composted rice straw. The second factor was nematicide application consisted of without nematicide, neemcake and carbofuran. Variables measured were N2O flux, rice grain yield and nitrogen uptake. Incorporation of fresh and composted rice straws reduced N2O flux about 49.2% and 59.9% in transplanted rice, and 32.9% and 28.2% in direct seeded rice, respectively. The neemcake application reduced N2O emission about 44-50%, while carbofuran application decreased N2O emission by 23-35%. Neemcake has a good potential as nitrification inhibitor of N2O emission, so the neem trees have a prospect to be cultivated intensively. The reduction of N2O emission was effective in direct seeded rice system with the application of neemcake and fresh rice straw, however, in transplanted rice system it was effective with neemcake and composted rice straw applications.

63-70

Authors: Budi Tangendjaja

Dried distillers grains with solubles (DDGS) is a co-product of ethanol industry made from grains through fermentation process and it can be used for animal feeding especially for dairy cows. A feeding trial on US corn DDGS was conducted at commercial dairy farm in Vietnam during hot condition in 2010. One hundred and fifty six dairy cows in a later stage of milk production were allotted randomly in three groups of 52 cows with similar milk production. Three dietary treatments offered comprised control diet, diet with 7.5% DDGS and diet with 15% DDGS. The diets were formulated to contain similar nutrient profiles and comprised forages (corn, elephant grass and alfalfa hay), brewery waste, soybean curd waste, corn, soybean meal, molasses and commercial dairy supplement. The diet was manufactured locally in total mixed ration system and delivered two times per day. Milk production, feed consump-tion and milk quality were measured for 5 days before the trial and 45 days after the trial. The result demonstrated that feeding DDGS could support higher milk production without affecting feed consumption. Feeding DDGS at 7.5% and 15% resulted in higher milk production of 2 and 4 kg per day respectively compared to cows fed control diet. Feed intake remained unaffected at around 35 kg per day. Milk quality as measured by total solid and fat content was similar in cows fed the control diet and DDGS at 7.5%. Feeding DDGS at 15% tended to have slightly better total solid and fat content. Feeding DDGS was able to reduce cost of the diets; diet cost for control, DDGS 7.5% and DDGS 15% were VND 2537, 2460 and 2399 per kg, respectively. It is concluded that DDGS can be economically used for feeding dairy cows in hot climate condition and improving milk production.

79-86

Authors: Meynarti Sari Dewi Ibrahim, Rr. Sri Hartati, Rubiyo, Agus Purwito, Sudarsono

Propagation of Coffea arabica L. through direct and indirect somatic embryogenesis technique is promising for producing large number of coffee seedlings. The objectives of the research were to evaluate methods for direct and indirect somatic embryo-genesis induction of C. arabica var. Kartika. The explants were the youngest fully expanded leaves of arabica coffee. The evalu-ated medium was modified Murashige and Skoog (MS) medium supplemented with a combination of 2.26 µM 2,4-D + 4.54 or 9.08 µM thidiazuron; 4.52 µM 2,4-D + 4.54 or 9.08 µM thidiazuron; or 9.04 µM 2,4-D + 9.08 µM thidiazuron. Both calli (100 mg) and pre-embryos developed from the edge of leaf explants were subcultured into regeneration medium (half strength MS with modified vitamin, supplemented with kinetine 9.30 µM and adenine sulfate 40 mg L-1). The results showed coffee leaf explant cultured on medium containing 2.26 µM 2,4-D + 4.54 or 9.08 µM thidiazuron to induce direct somatic embriogenesis from explant, while that of 4.52 or 9.04 µM 2,4-D + 9.08 µM thidiazuron to induced indirect somatic embrio-genesis. The medium for calli induction from coffee by explants was medium supplemented with 4.52 or 9.04 µM 2,4-D in combination with 9.08 µM thidiazuron. On the other hand, the best medium for activation of induction of somatic embryos was MS medium supplemented with 9.04 µM 2,4-D + 9.08 µM thidiazuron. Based on this results, the first step for developing micropropagation for coffee has been resolved. The subsequent studies will be directed to evaluate agronomic performance of the derived planting materials.