Judul: Mempelajari Pengaruh Pengolahan Tanah terhadap Tahanan Penetrasi Tanah di Kebun Percobaan Darmaga IV IPB, Bogor
Abstrak: Tujuan penelitian ini adalah untuk mempelajai pengaruh pengelolaan tanah khususunya metoda pengolahan tanah terhadap tahanan penetrasi tanah, serta mengetahui hubungan antara kadar air tanah dan bulk density tanah dengan tahanan penetrasi tanah.
Keyword: 

Judul: Dinamika Penetrabilitas Tanah pada Berbagai Penggunaan Lahan di Tanah Latosol, Darmaga
Abstrak: Plant roots that functioning to absorb water and nutrients can be inhibited when soil penetrabilty is quite high. Soil penetrability can be affected by soil properties, for example texture, bulk density, organic matter content, soil water content, matrix potential, calcium carbonate, and types of clay mineral. Of the soil properties, there are some that can be influenced by the type of land use. This study examined the penetrability of soil in various land uses. There was a series of observation of soil penetrability and soil properties in a variety of land use conducted in this research in order to study the relationship of soil properties on soil penetration resistance, soil water content relationship with penetrability, and resistance dynamics of land penetration in various land uses. The results showed that the soil texture class in the three land uses was clay. The highest clay percentage was found in grasslands both in the depth of 0-10 cm (82.00%) and 10-20 cm (81.90%). The highest soil bulk density in the depth of 0-10 cm was found in grasslands (1.09 g/cm3) and in the depth of 10-20 cm was found in mixed farms (1.13 g/cm3). The organic matter content in the depth of 0-10 cm was found in mixed farms (4.80%) and in the depth of 10-20 cm was found in secondary forest (3.18%). The index of soil aggregate stability of the three land uses were classified as a very stable class. Soil total pore space in the depth of 0-10 cm was found in secondary forest (61.52%) and in the depth of 10-20 cm was found in grasslands (59.15%). The three land uses had higher micro pore compared to the micro pore them selves. The different properties of soil had different effects on soil penetration resistance. Grassland showed the highest value of soil penetrability because of its high level of soil bulk density and clay. Secondary forest had the lowest soil penetrability value due to its high soil organic matter, low soil density, low micro pore space, and very stable soil aggregates. The relationship of soil penetration resistance with water content in three land uses was presented in power regression models with different determination coefficient. In the depth of 0-10 cm, the relationship had R2 of 0.53 in secondary forest, 0.35 in mixed farms, and 0.19 in grasslands. In the depth of 10-20 cm, the relationship of soil penetrability with moisture content had R2 of 0.29 in secondary forest, 0.26 in garden mix, and 0.11 in grasslands. In the days of no rain, the resistence of soil penetration had increased sharply since the third day in secondary forests, since the fifth day in mixed farms, and since the fourth day in grasslands in 0-20 cm deep. The resistence of soil penetration at each land use after 12 days of no rain increased because the soil was drier and harder, however, it did not inhibit the growth of plant roots.
Keyword: physical properties of soil, land use, penetration resistance, water content, Bogor Agricultural University (IPB)

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