Judul: Characterization and evaluation of seeded and seedless Indonesian pummelo {citrus maxima (burm.) Merr.} accessions
Abstrak: Indonesia has many accessions of pummelo germplasms, but only a small number of the accessions are planted commercially. Genetic variation in the seed number per fruit in pummelo is high, ranging from seedless to very seedy. Thus pummelo is categorized as seeded, potentially seedless and seedless. The objectives of this research were: 1) to identify morphological, biochemical (isozyme) and molecular (ISSR) characters, and ploidy level of seeded and seedless pummelo accessions originated from Sumedang, Pati, Kudus and Magetan, 2) to identify fruit formation of seeded and seedless pummelo, 3) to evaluate fruit quality of seeded and seedless pummelo fruit quality during storage. The characterization research showed that morphological characters contributed in grouping pummelo accessions were epicarp thickness, leaf lamina margin, vesicle length, epicarp color, petiole wing width and fruit shape, while based on isozyme characters were MDH (Rf 0.11 and 0.14) and ACP (Rf 0.24 and 0.33). ACP band at Rf 0.24 could be used as marker to differentiate seeded and seedless pummelo accessions. Molecular characters supported in classification of pummelo accessions were PKBT8 500 bp, PKBT8 375 bp, PKBT7 750 bp, PKBT3 750 bp, PKBT8 625 bp and PKBT12 500 bp. Separation between seeded and seedless cultivars based on morphological characters occured at similarity coefficient of 0.63, while on isoenzyme characters occured at similarity coefficient of 0.49. Both seeded and seedless pummelo accessions were diploid (2n = 2x = 18). Observation on fruit formation between selected seeded and seedless pummelo demonstrated that those pummelo accessions were able to produce parthenocarpic fruits, but bored seeded fruits when self pollination was induced, thus indicated self-compatibility. Natural self-pollination on ‘Bali Merah 1’, ‘Bali Merah 2, ‘Nambangan’ and ‘Bageng’ yielded seedless fruits, but most of ‘Jawa 3’ was seeded. Artificial self-pollination on those accessions produced seeded fruits, thus showed ovule fertility. ‘Bali Merah 2’ was shown to have high parthenocarpic degree as indicated by less seed number (<10 seed per fruit) in all pollination treatments. Therefore seedlessness in those pummelo accessions was caused by parthenocarpy, was not by pollen and ovule sterility, selfincompatibility, or poliploidy. Evaluation of pummelo fruit quality showed seedless pummelos have higher vitamin C, naringin content and acidity than seeded accessions. Vitamin C and titratable acidity (TA) content decreased, but total soluble solids (TSS) and TSS/AT ratio increased during storage period. During storage, percentage of edible portion increased, mainly due to the decrease of peel weight. Percentage of fruit axis of seedless accessions was smaller than those of seeded accessions. Sensory analysis indicated ‘Jawa 1’ seedless accessions have superior quality based on hedonic and scale quality test.
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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: Solusi Geometri Schwarzschild untuk Dimensi 4+1 dengan Invarian Rotasi Isotropik.
Abstrak: Metrik Schwarzschild merupakan solusi eksak pertama dari persamaan medan Einstein dengan mangasumsikan metrik statik dan simetris. Metrik Schwarzschild yang ditemukan oleh Karl Schwarzschild masih dalam dimensi 3+1, namun seiring dengan teori-teori terbaru yang menunjukkan bahwa alam semesta tidak hanya di dimensi 3+1. Maka melalui penambahan dimensi, tujuan penelitian ini memperoleh solusi pada geometri Schwarzschild untuk dimensi 4+1 dengan memodifikasi koordinat bola yang invarian rotasi isotropik dan melalui penurunan rumus seperti koordinat bola, simbol Christoffel, dan tensor Ricci. Selain mendapatkan solusi ini, metrik Schwarzschild dimensi 4+1 dapat digunakan sebagai metrik dasar untuk memperoleh solusi blackhole dan wormhole pada dimensi 4+1. Hasil akhirnya, dengan memanfaatkan modifikasi koordinat bola, metrik Schwarzschild dapat dibentuk sehingga diperoleh solusi geometri Schwarzschild untuk dimensi 4+1.
Keyword: metrik Schwarzschild, persamaan medan Einstein, modifikasi koordinat bola, penambahan dimensi, invarian rotasi isotropik