Judul: Pengaruh Perubahan Gigi Transmisi Traktor Yanmar 330T Terhadap Sifat Fisik Tanah Hasil Pengolahannya
Abstrak: Untuk mendapatkan efisiensi kerja, efisiensi tenaga serta efisiensi antara input yang digunakan dengan output yang didapatkan pada pengolahan tanah dengan traktor Yanmar 330T maka perlu dilakukan pe- nelitian yang terus menerus dari berbagai macam ke- adaan. Pada umumnya seorang operator menginginkan pe- kerjaannya cepat terselesaikan dengan memakai gigi transmisi tinggi (L4) dan pada rpm mesin yang ting- gi pula (1800 rpm). Pada penelitian ini dilakukan untuk mencari pengaruh perubahan gigi transmisi trak- tor Yanmar 330T dengan alat pengolah tanah bajak pi- ring sebagai pengolah tanah pertama dan garu piring sebagai pengolah tanah kedua pada jenis tanah lato- sol terhadap sifat fisik tanah dari hasil pengolahan- nya. Perlakuan yang diberikan adalah dengan merubah gigi transmisi L₁, 13 dan I L4 pada saat pengolahan de- ngan garu piring sebagai pengolah tanah kedua. Sedangkan sifat fisik tanah yang diukur adalah cone index, bulk density, porositas tanah, kadar air ...
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Judul: Mempelajari Pengaruh Lintasan Roda Traktor Terhadap Perubahan Bulk Density dan Soil Resistance serta Analisa Kebutuhan Tenaga Pengolahan Tanah Berdasarkan Soil Resistance di Pg. Jatitujuh Cirebon
Abstrak: Penelitian ini bertujuan mempelajari pengaruh lintasan roda traktor dalam pengolahan tanah terhadap peru- bahan bulk density dan soil resistance serta menganalisa kebutuhan tenaga pengolahan tanah. Percobaan dilakukan di lahan perkebunan tebu Pabrik Gula Jatitujuh Cirebon selama bulan Oktober 1984. Pengolahan tanah menggunakan traktor Kubota 7500 DT dengan implement Disc Plough, Chisel Plow dan Forrower dengan jumlah lintasan menurut metoda pengolahan lahan kering yang efektif. Klasifikasi tanah adalah Mediteran Akuik Vertik dengan kadar liat tinggi dan drainase jelek. Analisa data menggunakan analisa regresi kuadratik dan linier untuk menyatakan hubungan faktor-faktor yang diamati. Hasil penelitian menunjukkan bahwa faktor lintasan berpengaruh nyata terhadap perubahan bulk density dan soil resistance.
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Judul: Systematics of Desmos (Annonaceae) in Malesia
Abstrak: Desmos is a woody climbing genus of Annonaceae which has been widely used as traditional medicine in several countries such as China, Indo-China, Thailand, and Peninsular Malaysia to treat dysentery, vertigo, fever, and postpartum. Phylogenetic studies on Desmos showed a close relationship between Desmos and Dasymaschalon. They share similar moniliform monocarpic fruits, but their flowers are different. It has been debated among Annonaceae researchers whether both genera should be treated as the same or distinct genus. Therefore, investigation on the taxonomic delimitation of Desmos species and Dasymaschalon will be necessary. Plastid genome (plastome) identification, leaf epidermal section of Desmos species and Dasymaschalon species, a taxonomic revision of Desmos in Malesia using morphological data, the spatial distribution of Desmos species in Malesia, and morphological and genetic variation in Desmos chinensis population using ISSR marker were used to investigate taxonomic delimitation of Desmos. Plastome study of Desmos chinensis and Dasymaschalon dasymaschalum was carried out to determine the origin, evolution, phylogenomics, and identify marker candidates for Desmos and Dasymaschalon or with other genera in Annonaceae. We discovered that the plastome of Desmos chinensis was circular with the size of 167,677 bp (smaller than Dasymaschalon dasymaschalum), consist of 111 genes, including 78 protein-coding genes, 29 transfer RNAs, and 4 ribosomal RNAs. The plastome showed a typical quadripartite structure, i.e., large single copy (LSC), small single copy (SSC), and two inverted repeats (IRs). The plastome of Dasymaschalon dasymaschalum was 191,488 bp in length, which also exhibited a typical quadripartite structure (LSC, SSC, and two IRs). Desmos chinensis and Dasymaschalon dasymaschalum showed different copies of accD, ndhD, ndhF, rps18, and ycf2. Protein coding genes of rpoB, rpoC1, rbcL, matK, rpl32, infA, and rpl36 were identified based on nucleotide diversity, sequence variability, and parsimony-informative sites. The genes are defined as molecular marker candidates of plastome for phylogenetic, barcoding, and population genetic research. We predicted that Desmos chinensis and Dasymaschalon dasymaschalum separated at ca. 64 million years ago during the Paleocene. Leaf anatomical feature study was carried to support the taxonomic delimitation of interspecific Desmos and intergeneric of Desmos and Dasymaschalon. Leaf anatomy in the paradermal section of 20 taxa (12 species of Desmos, eight species of Dasymaschalon) have been carried out. According to the leaf epidermal section, Desmos and Dasymaschalon are two distinct genera mainly distinguished based on the anticlinal wall undulation of epidermal cells and supported by variation of the crystal type and size. The anticlinal wall undulation of Desmos was almost straight to slightly wavy and never sinuous; meanwhile, Dasymaschalon varies from almost straight to deeply sinusoid. The crystals of Desmos consist of rhombohedral, druse type A, and druse type B crystals, whereas Dasymaschalon has prism, druse type A, druse type B, and druse type C crystals. The recent taxonomic revision using the morphological data was mainly based on the examination of about 1374 specimens from BO, L, WAN, ANDA, SING, SAN, K, P, HUH herbaria. The Desmos species in Malesia consists of eight species: D. acutus, D. chinensis, D. chryseus, D. dunalii, D. pedunculosus, D. subbiglandulosus, two new records: D. lawii and D. macrocarpus, and one
Keyword: Dasymaschalon, Desmoid clade, Magnoliid, plastid genome, phylogenomics analysis