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: Pemanfaatan Bakteri Rhizoplane dan Fungi Mikoriza Arbuskula (FMA) Untuk Meningkatkan Pertumbuhan Semai Jelutung (Dyera polyphylla Miq. Steenis.)
Abstrak: Nontimber forest products (NTFPs) represent sources of income from tropical forest, but some NTFP species have decreased in population and become endangered due to overexploitation. There is increasing concern that the planting stock of Dyera polyphylla is not sufficient to sustain the yield of NFTPs. The beneficial root colonizing rhizosphere bacteria, the so-called plant growthpromoting rhizobacteria have been known to carry out many important ecosystem processes, such as those involved in the nutrient cycling and/or seedling establishment. The roots of most plant species associate with certain soil fungi and establish what are known as mycorrhiza. The objective of this study was to determine the effect of two arbuscular miycorrhizal (AMF) fungi, Glomus sp., Gigaspora sp. and thirteen strains of rhizoplane bacteria (CK32, FL.13.2.1, JW1, JW6, JW9, JW13, JW14, CK26, CK4, JW3a, SB, NT, CR.R1), on the early growth of D. polyphylla, under greenhouse condition. Percentage of AMF colonization, plant growth, and nitrogen (N) and phosphorus (P) concentration were measured after 150 days of planting. The results showed that the percentage of AM colonization of D. polyphylla was 100%. Colonization by Glomus sp. significanly increased plant height by 18,95% and diameter by 16,16% compared to those non AMF. Combination of bacterial and AMF inoculant between JW13 dan Glomus sp. increased shoot weight by as much as 36,28% from control and increased N concentration by 69,59% compared to those of non inoculate a seedlings. Combination of JW1 and Gigaspora sp. increased P concentration by as much as 42,05% compared to those of non inoculate seedlings. Despite the difficulty of selecting a multifunctional microbial consortia, appropriate microbial combinations can be recommended for a biotechnological input related to improvement of plant performance.
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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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