Judul: Potensi Trichoderma spp. Sebagai Agens Hayati dalam Pengendalian Ganoderma sp. yang Menyerang Tanaman Sengon.
Abstrak: Sengon (Falcataria mollucana) merupakan tanaman hutan rakyat yang banyak dikembangkan oleh petani hutan rakyat Indonesia, terutama di Pulau Jawa. Dewasa ini penanaman sengon lebih banyak ditanam secara monokultur sehingga menimbulkan berbagai permasalahan yang serius. Salah satu masalah yang muncul adalah serangan penyakit Ganoderma sp. yaitu cendawan patogen yang dapat menyebabkan penyakit busuk akar. Tujuan penelitian ini yaitu untuk mempelajari kemampuan Trichoderma spp. dalam menghambat pertumbuhan Ganoderma sp. secara in vitro dan mengevaluasi kemampuan Trichoderma spp. untuk mengendalikan Ganoderma sp. pada substrat balok kayu sengon di rumah kaca. Penelitian ini dilakukan dengan tiga tahapan percobaan. Penelitian I, studi pertumbuhan Ganoderma sp. dan Trichoderma spp. secara in vitro. Penelitian II, uji penghambatan Trichoderma spp. terhadap pertumbuhan Ganoderma sp. Penelitian III, pengendalian Ganoderma sp. pada balok kayu sengon di Rumah Kaca. Hasil penelitian studi pertumbuhan diameter koloni Ganoderma sp. menunjukkan bahwa laju pertumbuhan koloni Ganoderma sp. tercepat pada media PDA selama 12 hari dan pada media MEA selama 14 hari cawan Petri terisi penuh dengan koloni. Rata-rata pertumbuhan koloni isolat Ganoderma sp. sebesar 7.09 mm hari-1 pada media PDA nyata lebih cepat dibanding pertumbuhan koloni isolat Ganoderma sp. pada media MEA sebesar 5.41 mm hari-1. Hasil penelitian studi pertumbuhan diameter koloni Trichoderma spp. menunjukkan bahwa laju pertumbuhan diameter koloni Trichoderma spp. secara berturut-turut tertinggi pada T. pseudokoningii sebesar 38.14 mm hari-1 nyata lebih cepat dibanding T. viride sebesar 27.71 mm hari-1 dan T. harzianum 26.31 mm hari-1. Uji penghambatan Trichoderma spp. terhadap pertumbuhan Ganoderma sp. pada media PDA diperoleh rata-rata persentase penghambatan terbaik pada T. harzianum sebesar 74.19% nyata lebih cepat dibanding T. pseudokoningii sebesar 59,37% dan T. viride sebesar 41.36%. Demikian halnya pada media MEA diperoleh rata-rata persentase penghambatan terbaik pada perlakuan T. harzianum (73.00%), berbeda nyata dengan T. pseudokoningii (60.22%), dan T. viride (51.58%). Hasil penelitian pengendalian Ganoderma sp. pada balok kayu sengon di rumah kaca diperoleh penurunan pertumbuhan panjang koloni Ganoderma sp. satu minggu setelah balok kayu dibenam (Xt1) diperoleh nilai penurunan panjang koloni tertinggi pada perlakuan tanah steril + T. harzianum (1.12 cm), sedang pada perlakuan tanah steril tanpa T. harzianum terjadi pertambahan panjang koloni sebesar 0.67 cm. Demikian halnya pada dua minggu setelah balok kayu di benam (Xt2) pada perlakuan tanah steril + T. harzianum terjadi penurunan panjang koloni tertinggi sebesar 2.41 cm, sedang pada perlakuan tanah steril tanpa T. harzianum terjadi pertambahan panjang koloni Ganoderma sp. sebesar 1.22
Keyword: 

Judul: Potensi Trichoderma spp. Sebagai Agens Hayati dalam Pengendalian Ganoderma sp. yang Menyerang Tanaman Sengon
Abstrak: Sengon (Falcataria mollucana) is one of the forestry plant that widely developed by the community of Indonesia farmers especially in Java Island. Nowadays, sengon is widely planted with a monoculture system, therefore emerging many serious problems in silvi-culture. One of the serious problems was attacked by the pathogenic fungi, Ganoderma sp., which mainly caused root rot diseases. This research was aimed to investigate the ability of Trichoderma spp. in controlling the in vitro growth of Ganoderma sp. and to evaluate the capability of T. harzianum in inhibiting the growth of Ganoderma sp. on sengon timber substrate at greenhouse. This research was carried out in three experimental stages as follow: stage 1: study the growth activity of Ganoderma sp.; stage 2: study the inhibition activity of Trichoderma spp. towards the growth of Ganoderma sp. and stage 3: control the growth of Ganoderma sp. on Sengon timber substrate at greenhouse. Our results showed that the growth rate of Ganoderma sp. was expert on PDA and MEA medium each 12 days and 14 days incubation, respectively. Afterwards, the petridish was full of the Ganoderma sp. mycelium after 14 days incubation. In this study, the average value of the growth of Ganoderma sp. on PDA medium (7.09 mm day-1) was significantly differs to the growth of Ganoderma sp. on MEA medium (5.41 mm day-1). Besides of that, the fastest growth of Trichoderma spp. was shown by T. pseudokoningii such as 38.14 mm day-1 and significantly differs to T. viride, 27.71 mm day-1 and T. harzianum, 26.31 mm day-1. Based on antagonistic test, T. harzianum exhibited the best inhibition to Ganoderma sp. on PDA medium up to 74.19% and significantly differ to T. pseudokoningii 59.37% and T. viride 41.36%. Similarly on MEA medium treatment T. harzianum exhibited the best inhibition to Ganoderma sp. up to 73.00% and significantly differ to T. pseudokoningii 60.22% and T. viride 51.58%. The inhibition growth of Ganoderma sp. on sengon timber substrate at greenhouse showed that after 1 week, there was a decreasing growth of Ganoderma sp. mycelium when the sengon timber was submerged (Xt1) and obtained the highest value of inhibition up to 1.12 cm on sterile soil treatment + T. harzianum, whilst on sterile soil treatment without T. harzianum, there was an increasing growth of Ganoderma sp. mycelium up to 0.67 cm. Likewise, after 2 weeks of sengon timber submersion (Xt2) on sterile soil treatment + T. harzianum there was a decreasing growth of Ganoderma’s mycelium up to 2.41 cm, whereas on sterile soil treatment without T. harzianum, there was an increasing growth of Ganoderma sp. mycelium up to 1.22 cm.
Keyword: 

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.
Keyword: