Judul: The Growth and Tuber Yield of Sweetpotato (Ipomoea batatas L.) Ase Kapas at Various Rates of Nitrogen Fertilizer
Abstrak: Ubijalar merupakan tanaman pangan penting di Indonesia. Produktivitas ubijalar dapat dipengaruhi oleh pemupukan. Tujuan penelitian ini yaitu menentukan dosis nitrogen bagi pertumbuhan dan produksi ubijalar Ase Kapas. Penelitian dilakukan pada bulan Januari sampai Juli 2020 di Kebun Percobaan Cikabayan IPB dengan rancangan kelompok lengkap teracak dengan 3 ulangan. Dosis N yang diaplikasikan yaitu 0; 22,5; 45; 67,5; dan 90 kg ha-1 . Bahan tanam yang digunakan yaitu bagian stek pucuk. Curah hujan selama penelitian cenderung tidak sesuai dengan kondisi optimal pertumbuhan ubijalar. Pada tanah dengan kandungan nitrogen berstatus sedang (0,29% setara dengan 174 kg ha-1 ), dosis N tidak berpengaruh signifikan terhadap perubahan panjang dan diameter sulur, jumlah daun dan cabang, panjang dan diameter umbi, serta bobot basah dan kering umbi dan brangkasan. Pada tanah dengan kandungan N total sedang, dosis 0 kg N ha-1 dapat diaplikasikan untuk mendukung pertumbuhan dan produksi yang baik bagi ubijalar klon Ase Kapas., Sweetpotato is an essential crop plant in Indonesia. The productivity of the sweetpotato could be affected by fertilization. The objective of this research is to assess optimal nitrogen rate for growth and root yield of sweetpotato Ase Kapas. The experiment was conducted at IPB University experimental field Cikabayan from January to July 2020 used randomized complete block design with 3 replications. The level of nitrogen fertilizer consists of 0; 22,5; 45; 67,5; and 90 kg ha-1 . The planting material is the vine cuttings. The rainfall during this experiment tends to be insufficient as climate requirements. In the soil with moderate N content (0.29% equal to 174 kg ha-1 ), nitrogen had no significant effect on the growth of length and diameter of main stem, the amount of leaves and secondary stems, length and diameter of storage roots, wet- and dry-weight biomass of storage roots and aboveground part. In the soil with a moderate N total, dose of 0 kg N ha-1 could be applied to support good growth and yield of sweetpotato clone Ase Kapas.
Keyword: produktivitas, suplai nitrogen, umbi, Urea, nitrogen supply, storage root, productivity

Judul: The Growth and Prodution of Sweet Potatoes (Ipomoea batatas L.) Ase Kapas Clones With Different Doses of Phosphorous Fertilizer.
Abstrak: Ubi jalar merupakan sumber karbohidrat non beras yang mampu meningkatkan ketersediaan pangan dan diversifikasi pangan. Pemupukan salah satu faktor penting dalam budidaya tanaman ubi jalar. Penelitian ini bertujuan untuk menguji beberapa dosis fosfor optimal terhadap pertumbuhan dan produksi ubi jalar varietas ase Kapas. Percobaan penelitian ini dilakukan di Kebun Perobaan Cikabayan IPB dan Laboratorium Pasca Panen dari bulan Januari 2020 hingga Juli 2020. Percobaan penelitian disusun dalam Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan lima taraf percobaan yaitu 0 kg ha-1 SP36, 50 kg ha-1 SP36, 100 kg ha-1 SP36, 150 kg ha-1 SP36, 200 kg ha-1 SP36 dari dosis pupuk rekomendasi (100 kg ha-1 SP36). Terdapat tiga ulangan dengan lima perlakuan sehingga ada 15 percobaan. Ubi jalar Ase Kapas menunjukkan respon kuadratik terhadap peningkatan dosis pupuk P untuk peubah pertumbuhan tajuk, jumlah daun aktif dan jumlah cabang dengan nilai maksimum pada rata-rata dosis pupuk 143,6 kg SP36 ha-1. Produksi umbi tidak menunjukkan respon yang nyata terhadap peningkatan dosis pupuk SP36. Pada kondisi tanah kebun percobaan dengan status P tersedia yang rendah (8,3 ppm atau setara 16,6 kg ha-1 pada kedalaman 20 cm) maka secara praktis pupuk SP36 dapat diberikan dengan dosis 150 kg SP36 ha-1 atau 150% dosis pupuk rekomendasi., Sweet potato is a source of non-rice carbohydrates that can increase food security and diversity food. Fertilization an important factor in the cultivation of the sweet potato plant. The research aimed to determine the optimum fertilizer doses of the fertilizer for the growth and production of seet potato Ase Kapas clone. The experiment was performed at the field experiment Cikabayan IPB and post-harvest laboratory from January 2020 to July 2020. The experiment was arranged in a Randomized Complete Design Group (RCBD) single with single factor of phosphor fertilier dose is 0, 50, 100, 150, 200 kg ha-1 SP36 (100 kg ha-1 SP36 is a reference dose). There were three repliations with five treatments that led to 15 trials. Ase Kapas sweet potato showed a quadratic response to an increase in the dose of phosphorus fertilizer for crown growth variables, the number of active leaves and the number of branches with maximum values in the range average 143,6 kg SP36 ha-1. Tuber production did not show a significant response to increasing the dose of SP36 fertilizer. In the soil conditions with low available phosphorus status (8,3 ppm or equivalent to 16,7 kg ha-1 at a deep of 20 cm), SP36 fertilizer can be given at a dose of 150 kg SP36 ha-1 or 150% of the reference dose.
Keyword: Phosphorus fertilizer, regression analysis, sweet potato

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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