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: WATER USE EFFICIENCY OF ARABICA COFFEE SEEDLINGS OF GAYO 3 VARIETY AT DIFFERENT WATERING INTERVALS
Abstrak: Penelitian ini bertujuan untuk menganalisis efisiensi penggunaan air pada bibit Kopi Arabika varietas Gayo 3 yang ditanam di Kebun Percobaan Cikabayan, Bogor. Fokus utama penelitian adalah menentukan interval penyiraman yang optimal untuk pertumbuhan bibit kopi dengan melibatkan pengukuran berbagai parameter pertumbuhan, seperti tinggi tanaman, panjang daun, lebar daun, dan jumlah daun di bawah perlakuan interval penyiraman yang berbeda. Media tanam yang digunakan pada penelitian ini adalah campuran top soil dan pupuk kandang berat sekitar 4 kg per polibag yang berdiameter 20 cm. Empat interval penyiraman yang diuji meliputi setiap 2 hari (P1), 4 hari (P2), 6 hari (P3), dan 8 hari (P4) dilakukan dalam paranet 75%. Penyiraman dilakukan dengan memberikan air sebanyak 500 ml dan jumlah air yang keluar dari media tanam diukur untuk dihitung menggunakan pendekatan neraca air. Hasil dari penelitian yaitu nilai efisiensi penggunaan air tertinggi merupakan penyiraman setiap 4 hari (P2) dengan nilai rata-rata sebesar 1.43 g/l. Sehingga, menghasilkan tinggi tanaman, panjang daun, dan lebar daun yang menunjukkan kondisi pertumbuhan optimal serta memenuhi kualitas bibit kopi sesuai standar Kementrian Pertanian. Interval ini menyediakan air dalam jumlah yang tepat tanpa menyebabkan kelebihan atau kekurangan. Sebaliknya, penyiraman setiap 2 hari (P1) menyebabkan kelebihan air dan menghambat aerasi akar, sedangkan penyiraman setiap 8 hari (P4) menyebabkan kekurangan air, sehingga tanaman mengalami stres dan pertumbuhannya terhambat. Temuan ini memberikan kontribusi penting bagi strategi pengelolaan air dalam pembibitan Kopi Arabika, khususnya untuk varietas Gayo 3, yang diharapkan dapat meningkatkan efisiensi penggunaan sumber daya air di kebun percobaan dan area budidaya lainnya., This study aims to analyze the water use efficiency of Gayo 3 variety Arabica Coffee seedlings grown at Cikabayan Experimental Farm, Bogor. The main focus of the study was to determine the optimal watering interval for coffee seedling growth by involving the measurement of various growth parameters, such as plant height, leaf length, leaf width, and leaf number under different watering interval treatments. The planting medium used in this study was a mixture of top soil and manure weighing about 4 kg per 20 cm diameter polybag. Four watering intervals were tested including every 2 days (P1), 4 days (P2), 6 days (P3), and 8 days (P4) under 75% shade cloth. Watering was done by giving 500 ml of water and the amount of water coming out of the growing media was measured to be calculated using the water balance approach. The result of the study is the highest water use efficiency value is watering every 4 days (P2) with an average value of 1.43 g/l. Thus, it produces plant height, leaf length, and leaf width that show optimal growth conditions and meet the quality of coffee seedlings according to the standards of the Ministry of Agriculture. This interval provides the right amount of water without causing excess or deficiency. In contrast, watering every 2 days (P1) causes excess water and inhibits root aeration, while watering every 8 days (P4) causes water shortage, resulting in plant stress and stunted growth. These findings make an important contribution to water management strategies in Arabica Coffee breeding, particularly for the Gayo 3 variety, which is expected
Keyword: efisiensi penggunaan air, interval penyiraman, pembibitan kopi arabika, pertumbuhan optimal

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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