Judul: Pengaruh sumber dan dosis pemberian magnesium terhadap pertumbuhan, produksi, dan mutu hasil tanaman tomat, kentang, dan kacang jogo pada andosol margahayu Lembang
Abstrak: Penelitian ini dilaksanakan di kebun percobaan Margahayu, Balai Penelitian Tanaman Pangan Lembang yang berada pada ketinggian 1200 meter di atas permukaan laut, dimulai dari Juni 1980 sampai dengan Februari 1981. Tujuan penelitian adalah untuk mengetahui respons tanaman tomat, kentang, dan kacang jogo terhadap pemberian Mg pada Andosol Margabayu Lembang. Disamping itu untuk mempelajari beberapa sumber Mg dan dosisnya baik dalam peningkatan produksi maupun hasil tanaman pada tanah tersebut. Hasil penelitian menunjukkan bahwa dosis dan sumber Mg tidak jelas mempengaruhi pertumbuhan vegetatif tanaman tomat, kentang, dan kacang jogo. Ada kecenderungan bahwa pemberian Mg dapat meningkatkan tinggi dan garis tengah batang tanaman tersebut. Pemberian Mg selain dapat meningkatkan ketersediaan Mg secara langsung, juga menyebabkan beberapa ciri kimia tanah mengalami perubahan. Jumlah Mg yang terekstraksi pada waktu inkubasi dua minggu tidak sama untuk setiap sumber, begitu pula perubahan nilai pH yang terjadi dengan pemberian Mg, nampaknya tidak tercerminkan dalam jumlah P-terekstrasi yang berarti. Walaupun demikian kadar N, P, dan terutama Mg dalam daun tomat, kentang, dan kacang jogo pada umur 35 hari dan 55 hari setelah tanam meningkat dengan adanya kenaikan Mg-tersedia dalam tanah tersebut. Tetapi kadar K dalam daun tanaman menurun dengan bertambahnya jumlab Mg yang diberikan.
Keyword: Potato;, Kacang jogo;, Tomato;, Bogor Agricultural University;

Judul: Pengaruh Pupuk Magnesium (Mg) Terhadap Produksi dan Serapan Hara N, P, K, Ca, Mg Tanaman Kacang Hijau di Latosol Darmaga
Abstrak: Magnesium nutrient is a part of chlorophyl substance. The deficiency of Mg in the plant will decrease. The objective of this research was to determine the effect of Magnesium Fertilizer (MgO) on production and uptake of Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca) and Magnesium (Mg) of mung bean plant in Latosol Darmaga. The research design used Randomized Complete Block Design, with consist of 8 treatments were control, NPK Std, NPK Std + Kieserit, NPK Std + MgO 1, NPK Std + MgO 2, NPK Std + MgO 3, NPK Std + MgO 4, NPK Std + MgO 5 with each treatments had 3 replications. The research result showed that the addition treatment of MgO generally increased the plant height and mung bean production (total beans weight /pot and beans weight of 50 grains), especially to the treatment of NPK Std+MgO 3. Analysis of plant and soil showed that the MgO fertilizer tend to reduce content and uptake of Mg in plant leaves, but tend to increase the content and uptake of K and Ca in leaves while treatment of MgO fertilizer significantly increased exchangeable Mg (exch Mg) of soil and whereas exchangeable Ca was not different.
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Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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