Judul: The Effect of Different Doses of Compound NPK Fertilization on Vegetative and Generative Growth in Pummelo Fruit (Citrus maxima (Burm.) Merr.)
Abstrak: Pamelo (Citrus maxima (Burm.) Merr.) merupakan salah satu jenis jeruk di Indonesia yang mempunyai ukuran buah lebih besar dibandingkan dengan jenis jeruk lain. Tujuan dari penelitian ini adalah mendapatkan rekomendasi dosis pemupukan NPK majemuk yang tepat. Penelitian dilaksanakan di Kebun Percobaan Cikabayan IPB dan Laboratorium pascapanen AGH dari bulan Desember 2019 sampai Juni 2020. Bahan utama yang digunakan dalam perobaan adalah jeruk pamelo kultivar nambangan. Percobaan menggunakan rancangan kelompok lengkap teracak (RKLT) dengan satu faktor yaitu perbedaan dosis pupuk total yang terdiri dari 4 perlakuan yaitu kontrol/tanpa pemupukan (P1), pemupukan dengan dosis total 4 kg (P2), pemupukan dengan dosis total 2 kg (P3), pemupukan dengan dosis total 1 kg (P4), dengan masing-masing 5 ulangan. Perlakuan P3 menunjukkan respon nyata lebih tinggi pada perkembangan diameter buah, bobot buah, diameter akhir buah, lingkar buah dan volume buah dibanding perlakuan lainnya. Buah pada perlakuan dosis pupuk total 2 kg (P3) juga memiliki respon yang lebih tinggi pada tebal kulit dan bobot kulit serta memiliki edible portion sebesar 62,4 %. Pada peubah rata-rata tunas vegetatif per pohon, rata-rata bunga per pohon, kelunakan buah, bobot daging buah, padatan terlarut total (PTT) dan kandungan vitamin C, perbedaan dosis pupuk total tidak memberikan pengaruh nyata pada setiap perlakuan. Kandungan asam (ATT) pada perlakuan P3 memberikan respon yang cenderung lebih tinggi dengan nilai sebesar 0,64 %., Pummelo or pomelo (Citrus maxima (Burm.) Merr.) is a type of citrus in Indonesia which bear a larger fruit compared to other citrus types. The purpose of this study was to obtain a suitable dosage recommendation for the application of compound NPK fertilizer. The research was carried out at Cikabayan Experimental Field, IPB University and AGH Postharvest Laboratory from December 2019 to June 2020. The main research material that was used in the experiment was the nambangan pomelo cultivar. The experiment was designed using randomized complete block design (RCBD) with one factor, the difference in the total dose of the fertilizer which consists of 4 treatments, namely control/without fertilization (P1), fertilization with a total dose of 4 kg (P2), fertilization with a total dose of 2 kg (P3), fertilization with a total dose of 1 kg (P4), with 5 replication each. The P3 treatment showed a significantly higher response to the development of fruit diameter, fruit weight, final fruit diameter, fruit circumference and fruit volume compared to other treatments. The fruit from the fertilization treatment with a total dose of 2 kg (P3) not only showed a higher response in peel thickness and peel weight but also had an edible portion of 62.4%. On the variables of average vegetative shoots per tree, average flower per pohon, fruit tenderness, fruit flesh weight, total soluble solids (TSS) and vitamin C content, the difference in total fertilizer dose did not have a significant effect on each treatment. The Total Titratable Acidity (TTA) in the P3 treatment gave a comparatively higher response with a value of 0.64%.
Keyword: Nambangan, Fruit Weight, Fruit Diameter, TSS, TTA, Vitamin C

Judul: The Effectiveness of Biofertilizer on The Vegetative Growth of Pummelo Trees (Citrus maxima (Burm.) Mer.).
Abstrak: Jeruk pamelo (Citrus maxima (Burm.) Merr.) merupakan salah satu jeruk yang banyak dibudidayakan di Indonesia. Akan tetapi, kekurangan hara pada tanaman berimplikasi pada penurunan kesehatan tanaman jeruk pada sentra produksi. Penelitian ini bertujuan mengetahui efektivitas penggunaan pupuk Bioboost terhadap pertumbuhan vegetatif tanaman pamelo. Penelitian dilaksanakan di Kebun Percobaan Cikabayan Bawah Departemen Agronomi dan Hortikultura, Kecamatan Dramaga, Kabupaten Bogor yang berlangsung selama empat bulan dari bulan Februari hingga Juni 2023. Penelitian ini menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) dengan satu faktor, yaitu dosis pupuk hayati Bioboost. Terdapat tiga taraf dosis pemupukan Bioboost, yaitu 0 L ha-1, 6,25 L ha-1, dan 12,50 L ha-1 dengan delapan ulangan. Hasil penelitian menunjukkan bahwa perbedaan dosis pupuk Bioboost dapat meningkatkan pertumbuhan tanaman pamelo yang ditandai dengan pengaruh berbeda sangat nyata (p < 0,01) pada tinggi tanaman, jumlah mata tunas, jumlah tunas, dan luas daun total per tanaman, serta pengaruh berbeda nyata (p < 0,05) pada jumlah daun dan panjang tunas total per tanaman. Perlakuan pemupukan Bioboost dengan dosis 12,50 L ha-1 menunjukkan hasil terbaik untuk peningkatan tinggi tanaman, jumlah mata tunas, jumlah tunas, panjang tunas total, jumlah daun, dan luas daun total per tanaman., Pummelo (Citrus maxima (Burm.) Merr.) is one of the citrus fruits widely cultivated in Indonesia. However, nutrient deficiencies in plants have implications for the decline in the health of pomelo plants in production centers. This research aims to determine the effectiveness of using Bioboost fertilizer on the vegetative growth of pomelo plants. The study was conducted at the Cikabayan Bawah Experimental Garden, Department of Agronomy and Horticulture, Dramaga Subdistrict, Bogor Regency, for a duration of four months from February to June 2023. The research used a Randomized Complete Block Design (RCBD) with one factor, which is the dosage of Bioboost biofertilizer. There are three levels of Bioboost fertilization doses, namely 0 L ha-1, 6.25 L ha-1, and 12.50 L ha- 1 with eight replications. The results of the study showed that different doses of Bioboost fertilizer can enhance the growth of pomelo plants, as indicated by highly significant differences (p < 0.01) in plant height, number of shoot buds, number of shoots, and total leaf area per plant, as well as significant differences (p < 0.05) in the number of leaves and total shoot length per plant. The application of Bioboost fertilizer with a dosage of 12.50 L ha-1 showed the best results in increasing plant height, number of shoot buds, number of shoots, total shoot length, number of leaves, and total leaf area per plant.
Keyword: citrus, cultivate, nutrient, bioboost, dosage

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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