Judul: Growth response and adaptation to drought stress of three forage legume crops inoculated with Arbuscular Mycorrhizal Fungi (AM-Fungi)
Abstrak: Di daerah tropika pada umumnya, termasuk Indonesia, terdapat berbagai jenis tanaman legum pakan, tiga di antaranya yang sudah tersebar luas dan populer di kalangan petani peternak yaitu Sentro (Centrosema pubescens Benth.), Kalopo (Calopogonium mucunoides Desv.), dan Puero [Pueraria phaseoloides Roxb. (Benth.)]. Ketiga jenis tanaman legum pakan ini biasanya dibudidayakan pada tanah -tanah marginal seperti Ultisol, di mana pada tanah ini tanaman akan menghadapi masalah defisiensi unsur hara esensial tertentu, selain juga pada musim kemarau dapat mengalami kondisi kekurangan air (cekaman kekeringan). Akibatnya pertumbuhan tanaman menjadi tidak optimal. Hal ini sangat penting untuk diperhatikan, mengingat dalam pembuatan padang penggembalaan baru terutama pada tahap ”pasture establishment” (pembentukan awal padang rumput), pertumbuhan awal tanaman yang baik akan memberi jaminan terhadap pertumbuhan selanjutnya sepanjang siklus hidupnya. Penggunaan mikro - organisme bermanfaat (CMA dan Rhizobium) merupakan salah satu alternatif pemecahan masalahnya.
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Judul: Forage legumes crops adaptation to drought stress and mycorrhizal inoculation
Abstrak: One of the major problems to ruminant production sustainable is forage availability. The problem is more influenced by the seasons, especially the dry season. Lack of soil water causes plants experiencing drought stress. To cope with drought stress, plants respond with physiological and biochemical changes. It’s causes plants undergo morphological and physiological disorders, and it will hampered their growth and productivity. Utilization of mycorrhizae may assist plants to overcome drought stress. The study was conducted to recognize adaptation mechanisms of legume inoculated with mycorrhiza on drought stress, investigate effect of mycorrhizal inoculation to leguminous adaptability to overcome drought stress, and to obtain forage legume species that adaptive and productive in drought condition. Ten tropical forage legumes species consisting of Leucaena leucocephala, Indigofera zollingeriana, Desmodium sp, Calopogonium mucunoides, Macroptilium bracteatum, Centrocema pascuorum, Pueraria javanica, Clitoria ternatea, Centrocema pubescen, and Stylosanthes seabrana) were tested in different drought condition (optimum watering, drought stress) as factor. The other factor was innoculation of mychorizal fungi (no mycorrhiza, with mycorrhiza), which expected to interact with the plants in reducing drought stress. Soil water content (swc), leaf water potential (lwp), leaf relative water content (lrwc), leaf proline, leaf water soluble carbohydrate (lwsc), and plant dry weight were observed. Drought stress decreased swc, lwp, lrwc and total dry weight. Drought stress also increased leaf proline and lwsc content, but lwsc was declined in Centrocema pascuorum. Mycorrhizal fungi inoculation effect was varied among legume species. Inoculation of mychorrizal fungi was increased leaf proline and lwsc content of all legume species. However, it was tended to decline proline content in tree legumes. Indigofera zollingeriana, Centrocema pascuorum and Clitoria ternatea were productive species that recommended for forage development in dry area.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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