Judul: Organogenesis and in vitro conservation of pummelo (Citrus maxima (Burm.) Merr.).
Abstrak: Indonesia has high diversity of pummelo (Citrus maxima (Burm.) Merr.) which economically potential. The pummelo diversity must be conserved to overcome its extinction due to biotic and abiotic stresses. In vitro conservation using slow growth technique can be considered as an alternative of ex-situ conservation. The objective of this research was to study pummelo organogenesis and to find out an effective medium to conserve pummelo using slow growth technique. Three experiments were conducted in this research to conserve pummelo. Organogenesis was induced on pummelo leaf, root and epicotyl to find out the best explant and medium to produce pummelo shoot effectively. Two conservation experiments using slow growth were conducted to find out the best medium to conserve pummelo. The first conservation experiment was done using reduction of MS medium and sucrose concentration, while the second conservation method was done using osmotic regulator and retardant. The results showed effective direct organogenesis of pummelo could be induced by culturing epicotyl explant vertically in MS medium without plant growth regulator under 24 hour light. In the first conservation experiment, the best medium to conserve pummelo using reduction of MS medium and sucrose concentration was MS medium without sucrose that inhibited leaf formation 37%, shoot elongation 75%, root elongation 49,4%, and the estimation to conserve pummelo was 30,7 months. While in the second conservation experiment, the best medium to conserve pummelo using osmoticum and retardant is MS + sorbitol 2% + paclobutrazol 7,5 ppm, that inhibited shoot length 65,1%, leaf formation 84,6%, root number 20%, root length 81%, and the estimation to conserve pummelo was 22,2 months. However, based on percentage of growth inhibition to the planlet and the appearance of the conserved planlet, the more suitable medium to conserve pummelo was MS + sorbitol 2% + paclobutrazol 7,5 ppm. After conservation periode, pummelo could grow normally in recovery medium (MS0) and aclimatization medium (soil : husk : compos = 2 : 1 :1).
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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: 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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