Judul: Growth of Water Spinach and Spinach Due to the Application of Inorganic Liquid Fertilizer in the Hydroponic System
Abstrak: Hidroponik adalah salah satu metode alternatif dalam budidaya sayur, metode ini tidak memerlukan area yang luas. Produksi dari hidroponik dapat ditingkatkan dengan pemenuhan nutrisi yang tepat. Penelitian ini bertujuan menganalisis efek penambahan pupuk anorganik cair pada larutan hara AB mix terhadap pertumbuhan tanaman kangkung dan bayam. Rancangan penelitian yang digunakan adalah Rancangan Acak Kelompok. Perlakuan yang diamati adalah konsentrasi larutan hara yang terdiri dari 3 taraf. Perbandingan air, larutan A, larutan B, dan pupuk cair (v/v) yaitu P0 (kontrol) = 1000:5:5:0, P1 =1000:5:5:5, dan P2 = 1000:5:5:15. Parameter yang diamati adalah tinggi tanaman, jumlah daun, jumlah cabang, luas daun, berat segar, berat kering, dilakukan juga uji kualitatif kandungan nitrat daun. Hasil penelitian menunjukkan bahwa perlakuan P0 memiliki pertumbuhan tercepat, sedangkan pertumbuhan paling lambat terlihat pada P2. Uji nitrat daun P2 menunjukkan hasil yang negatif. Perlakuan P0 juga memiliki berat segar dan berat kering tanaman yang paling tinggi dibanding dua perlakuan lainnya. Penambahan pupuk anorganik cair tidak dapat meningkatkan pertumbuhan pada kangkung dan bayam., Hydroponics is an alternative method in vegetable cultivation, this method does not require a large area. Hydroponics production can be increased with the fulfilment of proper nutrition. This research aimed to analyze the effect of adding liquid inorganic fertilizer to the AB mix nutrient solution on water spinach and spinach growth. This research used a Randomized Block Design. The treatments observed were the concentration of nutrient solution which consisted of 3 levels. The treatments were mixed of water, solution A, solution B, and liquid fertilizer (v/v), namely P0 (control) = 1000:5:5:0, P1 =1000:5:5:5, and P2 = 1000:5:5:15. The parameters observed were plant's height, number of leaves, number of branches, leaves area, leaves nitrate content, and plant fresh and dry weights. The results showed that the P0 treatment had the fastest growth, while the slowest growth was seen in P2. The leaf nitrate test of P2 plants showed negative results. The P0 treatment also had the highest fresh and dry weights per plant compared to the other two treatments. The addition of liquid inorganic fertilizer did not increase the growth of water spinach and spinach.
Keyword: AB mix, hydroponics, liquid inorganic fertilizer, spinach, water spinach

Judul: Optimizing Fertilizer Dosages in Water Spinach Cultivation Using Fertigation Through Drip Irrigation
Abstrak: Peningkatan produktivitas tanaman kangkung varietas Bangkok-LP1 dapat dilakukan dengan cara pemberian dosis pupuk yang optimum berdasarkan analisis tanah secara fertigasi melalui irigasi tetes. Penelitian ini bertujuan untuk mengetahui rekomendasi dosis pupuk yang tepat untuk tanaman kangkung sehingga mencapai produktivitas yang maksimal. Penelitian dilakukan mulai bulan Juli sampai Oktober 2023 di Kebun Percobaan Cikarawang, Institut Pertanian Bogor, yang memiliki jenis tanah inceptisol dengan kandungan C-Organik 1,38%, P-Tersedia 5,5 ppm (sangat rendah), K-Tersedia 33,1 ppm (rendah), dan pH 6,03 (masam). Penelitian ini menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) dengan satu faktor yaitu perlakuan 5 dosis pemupukan 0%X, 50%X, 100%X, 150%X, dan 200%X, dengan X adalah dosis 219 kg N ha-1, 374 kg P2O5 ha-1, 187 kg K2O ha-1 dengan 4 ulangan. Hasil penelitian menunjukkan bahwa aplikasi pemupukan menggunakan fertigasi melalui irigasi tetes sampai 200% rekomendasi Ferads tidak memberikan pengaruh yang nyata pada pertumbuhan dan produksi kangkung varietas Bangkok-LP1. Produktivitas kangkung varietas Bangkok-LP1 mencapai 13,64 ton ha-1 pada penanaman pertama, sedangkan pada penanaman kedua dengan residu pemupukan menghasilkan 12,33 ton ha-1., Increasing the productivity of the Bangkok-LP1 variety of water spinach plants can be done by providing optimum fertilizer rate based on soil analysis using fertigation through drip irrigation. This research aims to determine the recommended fertilizer rate for water spinach plants to achieve maximum yield. The research was conducted from July to October 2023 at the Cikarawang Experimental Station, Bogor Agricultural University, which has an inceptisol soil type with a C-Organic content of 1,38%, P-Available 5,5 ppm (very low), K-Available 33,1 ppm (low), and pH 6,03 (acid). This study used a Randomized Completely Block Design (RCBD) with one factor, with 5 level fertilizer rate of 0%X, 50%X, 100%X, 150%X, and 200%X, where 219 kg N ha-1, 374 kg P2O5 ha-1, 187 kg K2O ha-1 with 4 replications. The results of the research showed that fertilization application using fertigation through drip irrigation up to 200% as recommended by Ferads did not have a significant effect on the growth and yield of the Bangkok-LP1 variety of water spinach. The productivity of the Bangkok-LP1 variety of water spinach reached 13.64 tons ha-1 in the first planting, while in the second planting with fertilizer residue it produced 12.33 tons ha-1.
Keyword: ferads

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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