Judul: Evaluation of N, P and K Nutrient Pummelo Citrus Plantation (Citrus maxima (Burm.) Merr.)  in Pangkep with Nutrient Symptom Deficiency Methods, Plant Analysis and Soil Test Methods
Abstrak: Jeruk pamelo (Citrus maxima (Burm.) Merr.) merupakan salah satu buah yang digemari konsumen serta memiliki nilai ekonomi yang tinggi. Kabupaten Pangkep menjadi penghasil jeruk pamelo terbesar di Sulawesi Selatan namun, mengalami penurunan pada tahun 2018, 2019, dan 2020. Penurunan produksi dipengaruhi ketidakseimbangan hara esensial yaitu hara N, P dan K di dalam tanah. Penelitian ini bertujuan mengevaluasi status hara N, P dan K tanah kebun jeruk pamelo di Kabupaten Pangkep. Metode yang digunakan adalah gejala defisiensi hara, analisis tanaman, dan uji tanah. Tahapan awal dilakukan pengamatan gejala defisiensi hara pada daun yang memiliki ciri-ciri secara visual dan disesuaikan dengan pedoman kemudian diperkuat dengan analisis daun untuk menetapkan konsentrasi hara N, P dan K. Sampel tanah komposit diambil dari lokasi yang tanamannya tumbuh normal dan yang mengalami gejala defisiensi kemudian dianalisis untuk mengetahui kadar N, P dan K. Hasil analisis tanah menunjukkan N dan K berstatus rendah, baik pada jeruk pamelo tumbuh normal dan yang mengalami defisiensi N dan K. Tanaman yang menunjukkan gejala defisiensi N dan K menunjukkan analisis tanaman yang juga rendah. Gejala defisiensi secara visual P tidak ditemukan di lapangan dan hasil analisis tanaman menunjukkan konsentrasi P tergolong tinggi, walaupun hasil analisis tanah menunjukkan konsentrasi P yang tergolong rendah., Pummelo citrus (Citrus maxima (Burm.) Merr.) is one of the fruits that is favored by consumers and has a high economic value. Pangkep is the largest producer of pummelo citrus in South Sulawesi. The production, however, declined in 2018, 2019 and 2020. The decrease in production is influenced by the imbalance of nutrients N, P and K in the soil. The purpose of this study was to evaluate the status of nutrients N, P and K of pummelo citrus plantation in Pangkep. The methods used were symptoms of nutrient deficiency, plant analysis, and soil testing. The research was started by visual observation of N, P and K deficiency symptoms in leaves. Composite soil samples were taken from locations where plants grew normally and which had N, P or K deficiency symptoms. These samples were then analyzed to find out the levels of N, P and K. Soil analysis showed that N and K status were low in both, normal growing and N and K deficient pummelo citrus. Plants showing N and K deficiency symptoms showed low plant analysis. Visual deficiency symptoms of P were not found in the field and plant analysis results showed high concentrations of P, although soil analysis results showed low concentrations of P.
Keyword: leaves, fertilization, production

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: 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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