Judul: Mempelajari Pengaruh Berat pada Roda Penggerak Traktor terhadap Slip Roda pada Pengolahan Tanah dengan Bajak Piring
Abstrak: Slip berlebihan merupakan masalah yang dihadapi pada operasi pengolahan tanah utama untuk lahan berkadar liat tinggi . Faktor yang mempengaruhi besarnya slip yang terjadi selama pengolahan tanah antara lain adalah jenis dan kondisi tanah, alat traksi , kecepatan kerja , dan perpindahan distribusi berat pada as penggerak traktor selama operasi
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Judul: Hubungan antara pemadatan tanah dengan slip roda
Abstrak: Tujuan dari penelitian ini adalah menentukan hubungan antara slip roda dengan pemadatan tanah pada jenis tanah tertentu, sehingga dapat ditentukan tingkat slip yang sesuai agar pemadatan yang terjadi sekecil mungkin. Faktor-faktor yang berpengaruh terhadap pemadatan tanah antara lain: beban traktor, kadar air tanah, tekanan inflasi dan slip roda, serta masih banyak lagi. Pada penelitian ini dapat dilihat kombinasi hubungan dari beban, kadar air, tekanan inflasi ban dan slip terhadap pemadatan tanah. Analisis data percobaan digunakan analisis ragam dengan taraf 0.05 atau peluang 95%. Jenis tanah pada lahan percobaan adalah tanah bertekstur lempung liat berdebu. Hasil uji protor pada contoh tanah dihasilkan kepadatan maksimum terjadi pada kadar air 39% dengan bulk density wet 1.6922 g/cm³. Pengaruh kadar air tanah terhadap kohesi dan adhesi tanah mengakibatkan perubahan slip pada roda. Selain itu, besarnya pemadatan yang terjadi juga dipengaruhi oleh kadar air. ...
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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