Judul: Analysis of Leaf Growth Rate In Gayo 3 Arabica Coffee
and Its relationship With Growing Degree Days
Abstrak: Penelitian ini bertujuan untuk mengetahui Growing Degree Days (GDD) perkembangan daun bibit kopi arabika Gayo 3 di bawah paranet 75% dan paranet (waring) 25% yang sudah dilapisi dengan plastik. GDD menghitung jumlah satuan panas (? hari) yang dibutuhkan setiap pertambahan pasangan daun. Perhitungan GDD dilakukan sejak munculnya pasangan daun pertama yaitu pada hari ke 86 setelah tanam sampai bibit kopi berumur 206 hari. Hasil pengamatan selama periode tersebut pada paranet (waring) 25% menunjukkan rata – rata suhu udara maksimum dengan nilai 34,8 ?, Suhu udara minimum 23,8 ?, dan suhu udara rata – rata 27,4 ?. Paranet 75% memiliki fluktuasi suhu yang lebih rendah dibandingkan dengan paranet (waring) 25%, dimana rata – rata suhu udara maksimum pada paranet 75% menunjukkan nilai sebesar 32,1 ?, suhu udara minimum 21,0 ?, dan suhu udara rata – rata 24,6 ?. Rata-rata GDD untuk setiap pertambahan pasangan daun pada paranet 75% adalah 203? hari sedangkan pada paranet (waring) 25% adalah 241 ? hari. Terdapat kecenderungan GDD bibit kopi yang ditanam pada level radiasi yang lebih tinggi (paranet/waring 25%) memiliki nilai yang lebih tinggi dibandingkan bibit kopi yang ditanam pada level radiasi yang lebih rendah (paranet 75%). Meskipun demikian, hasil ini memerlukan kajian lebih lanjut untuk melihat konsistensi nilai GDD, mengingat umumnya bibit tanaman kopi merupakan tanaman yang membutuhkan naungan agar bisa tumbuh dan berkembang lebih optimal. Kata kunci: arabika, Growing Degree Days, laju perkembangan, This research aims to determine the Growing Degree Days (GDD) of Gayo 3 Arabica coffee seedling leaf development under 75% shade net and 25% shade net (covered with plastic). GDD calculates the amount of heat units (? days) required for the growth of each pair of leaves. The GDD calculation was carried out from the emergence of the first pair of leaves on the 86th day after planting until the coffee seedlings were 206 days old. Observations during this period under the 25% shade net showed an average maximum air temperature of 34.8 ?, a minimum air temperature of 23.8 ?, and an average air temperature of 27.4 ?. The 75% shade net had lower temperature fluctuations compared to the 25% shade net, with an average maximum air temperature of 32.1 ?, a minimum air temperature of 21.0 ?, and an average air temperature of 24.6?. The average GDD for each pair of leaves under the 75% shade net was 203 ? days, whereas under the 25% shade net, it was 241 ? days. There is a tendency for the GDD of coffee seedlings planted under higher radiation levels (25% shade net) to be higher than those planted under lower radiation levels (75% shade net). However, these results require further study to see the consistency of GDD values, considering that coffee seedlings generally need shade to grow and develop optimally. Keywords: arabica, Growing Degree Days, development rate
Keyword: arabika, growing degree days, laju perkembangan

Judul: Radiation Use Efficiency Arabica Variety Gayo 3 Coffee Seed at  Different Shading Intensities
Abstrak: Penelitian ini bertujuan untuk menganalisis pengaruh perbedaan intensitas radiasi matahari terhadap efisiensi pemanfatatan radiasi matahari (EPR) bibit kopi arabika varietas Gayo 3. Bibit kopi arabika varietas Gayo 3 ditanam di dalam pot dan ditempatkan di bawah naungan waring atau paranet – untuk mengurangi transmisivitas (??) radiasi matahari; dan di atasnya diberi plastik – untuk mencegah air hujan masuk dan mengenai pot tanaman. Ada 4 taraf perlakuan intensitas, yaitu N1 (waring+plastik, ?? = 76.1%), N2 (paranet 50%+plastik, ?? = 50.8%), N3 (paranet 75%+plastik, ?? = 25.5%), dan N4 (paranet 90%+plastik, ?? = 14.7%). Selama 74 hari penelitian, total radiasi global 1126.2 MJ/m2 dan yang ditransmisikan ke dalam ruangan dan mencapai tajuk bibit tanaman (MJ/m2) pada N1 adalah 855.8, N2 563.1, N3 269.2, dan N4 193.7. Hasil penelitian menunjukkan pengaruh nyata tingkat intensitas radiasi terhadap EPR bibit tanaman kopi arabika Gayo 3. Nilai EPR (g/MJ) pada perlakuan N1, N2, N3, dan N4 berturut-turut adalah sebesar 0.40, 0.72, 1.00, dan 0.99. Hasil tersebut mengindikasikan bahwa bibit tanaman kopi arabika Gayo 3 membutuhkan naungan untuk dapat tumbuh lebih optimal. Bibit tanaman kopi arabika Gayo 3 yang ditanam pada rata-rata intensitas harian (MJ/m2/hari) 3.5 (N3) dan 2.5 (N4) menunjukkan pertumbuhan lebih optimal dibandingkan dengan yang ditanam pada rata-rata intensitas harian yang lebih tinggi 10.7 (N1) dan 7.2 (N2). Hasil penelitian ini perlu dikaji lebih dalam untuk mendapatkan kisaran optimum intensitas radiasi yang dibutuhkan oleh bibit tanaman kopi arabika Gayo 3., The purpose of this research is to analyze optimum intensity of solar radiation for arabica variety Gayo 3 coffee seed growth which will be expressed by radiation use efficiency (RUE) value and productivity parameters. Arabica coffee seedlings of the Gayo 3 variety were planted in pots and placed under different level of shading by utilizing waring or paranet to reduce the transmissivity (t) of solar radiation; with a layer of plastic to prevent rainwater from entering and hitting the plant pots. There were 4 levels of intensity treatment, namely N1 (netting + plastic, t = 76.1%), N2 (50% paranet + plastic, t = 50.8%), N3 (75% paranet + plastic, t = 25.5%), and N4 (90% paranet + plastic, t = 14.7%). During the 74 days of the study, the total global radiation was 1126.2 MJ/m2, the amount that got transmitted into the greenhouse and reached the canopy of the seedlings (MJ/m2) at N1 was 855.8, N2 563.1, N3 269.2, and N4 193.7. The results showed a significant effect of different level of radiation intensity on the EPR of Gayo 3 Arabica coffee seedlings. The EPR values (g/MJ) in the N1, N2, N3, and N4 treatments were 0.40, 0.72, 1.00, and 0.99, respectively. These results indicate that Gayo 3 Arabica coffee seedlings need shade to grow optimally. The seedlings planted at an average daily intensity (MJ/m2/day) of 3.5 (N3) and 2.5 (N4) showed more optimal growth compared to those planted at a higher average daily intensity of 10.7 (N1) and 7.2 (N2). However, a further study regarding these results is still needed to obtain the optimum range of radiation intensity required by Arabica coffee seedlings of Gayo 3
Keyword: Gayo 3, Growth, Intensity, Seed and Shading

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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