Judul: Pengaruh perlakuan rizobakteri pada benih dan tanaman serta pemupukan fosfat terhadap pertumbuhan tanaman tetua betina jagung hibrida
Abstrak: The use of quality seeds from improved varieties will produce plants more productive and efficient. Seed quality constitute of genetic, physical, physiological, and health quality. Phosphate fertilizer can enhance plant growth, however only 10-30% of fertilizer P that can be absorbed by plants. The use of rhizobacteria can enhance phosphate uptake and plant growth. The objectives of this study were to improve the quality of physiological seeds and plant growth hybrid corn using rhizobacteria and phosphate fertilizers. The research has conducted in three stages of experiments in the laboratory, greenhouse and in the field. Experiment used parent of hybrid corn seed cv. Bima-3, namely: Nei9008 (female parent) and Mr14 (male parent). The groups of isolates Actinomycetes, Bacillus spp. and fluorescent pseudomonads are used in these experiments. The experiment steps were: (1) characterization and screening of rhizobakteria, (2) Evaluation of selected rhizobacteria on seed quality and seedling growth of female parent and (3) Effect of rhizobakteria treatment and phosphate fertilizer on plant growth of female parent. Experiment 3 were conducted in two seasons, season I using six isolates selected from Experiment 1 and 2, while the season II using two isolates which indicated the best result from season I. In the field experiment, the seeds has planted in polybags with sterilized soil. Experiment 3 was arranged in Split Plot Design. The main plot consisted of five doses of phosphate fertilizer, which is 0, 75, 125, 175, and 200 kg SP-36/ha (100% of recommended dosage). Subplot is rhizobacteria treatment. The results showed, there were five isolate choosed from 10 isolates of each genus of rhizobacteria based on the criteria of high producing phosphatase, negative hypersensitive reaction test, producing IAA and chitinase. Experiment 2 showed the rhizobacteria B28 and B46 increase growth rate and seed vigor index. The results of Experiment 1 and 2, rhizobacteria AB2, ATS4, B28, P14 and P31 was selected based on the ability to improve the physiological seed quality of female farent and rhizobacteria B42 based on the highest production of IAA (14.4 μg/ml). Field experiment at the season I, there were rhizobacteria ATS4 and B28 increased plant growht compare to other rhizobacteria. The results from season II, ATS4 has potential to promote plant growth with average number of leaf and plant height at 4 weeks after planting 5.2 and 56.88 cm compared to control 4.8 and 55.98 cm respectively. Phosphate fertilizer strongly influenced on the average number of leaves and plant height. In the season II at 2 and 4 weeks after planting, fertilizing with the recommended dose (200 kg SP-36/ha) showed highest average the number of leaves and the plant height compared with other treatments.
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Judul: Isolasi, Identifikasi, Serta Aplikasi Rhizobakteri Dan Pupuk Nitrogen-Fosfat Dalam Mempengaruhi Mutu Fisiologis Benih Dan Pertumbuhan Tanaman Tetua Betina Jagung Hibrida
Abstrak: Peningkatan produktivitas jagung dapat dilakukan dengan penggunaan benih bermutu dari varietas unggul seperti hibrida dengan memperhatikan kebutuhan nutrisi tanaman selama proses produksi di lapang. Nitrogen dan fosfat merupakan unsur hara esensial yang dibutuhkan tanaman pada seluruh fase hidupnya. Namun, ketersediaan unsur tersebut seringkali sedikit di dalam tanah. Pemanfaatan rhizobakteri penambat nitrogen dan pelarut fosfat pada benih tetua betina hibrida diharapkan dapat membantu pertumbuhan tanaman dengan meningkatkan ketersediaan unsur N dan P. Penelitian ini bertujuan untuk mendapatkan bakteri penambat N yang kompatibel dengan bakteri pelarut P dan mampu meningkatkan mutu fisiologis benih serta pertumbuhan tanaman tetua betina jagung hidrida. Percobaan menggunakan benih tetua betina jagung hibrida varietas Bima-3 yaitu Nei 9008. Penelitian ini terdiri atas percobaan di laboratorium dan di lapang dengan rangkaian sebagai berikut: (1) Isolasi, karakterisasi dan uji kompatibilitas rhizobakteri, (2) Pengaruh aplikasi bakteri penambat nitrogen dan pelarut fosfat terhadap viabilitas benih tetua betina jagung hibrida, dan (3) Pengaruh aplikasi bakteri penambat nitrogen dan pelarut fosfat serta dosis pupuk nitrogen fosfat terhadap pertumbuhan vegetatif tetua betina jagung hibrida. Isolasi dan identifikasi rhizobakteri serta uji viabilitas benih yang diberi perlakuan rhizobakteri dilakukan di Laboratorium Fisiologi dan Kesehatan Benih IPB. Percobaan di lapang dilaksanakan di Balai Besar Padi Instalasi Kebun Percobaan Muara, Bogor dan disusun dengan rancangan split plot RKLT menggunakan tiga ulangan. Benih ditanam dalam polibag hingga usia tanaman 4 minggu. Petak utama adalah dosis pupuk N dan P (0%, 25%, 50%, 75%, dan 100% dari dosis rekomendasi), dan anak petak adalah perlakuan rhizobakteri. Hasil menunjukkan bahwa bakteri penambat nitrogen berhasil diisolasi yaitu 35 isolat Azotobacter dan 42 isolat Actinomycetes dari beberapa lokasi di wilayah Bogor. Sebanyak 25 isolat Azotobacter dan 29 isolat Actinomycetes memiliki kemampuan menambat nitrogen. Bakteri penambat nitrogen diuji kompatibilitasnya dengan bakteri pelarut fosfat. Bakteri yang kompatibel diaplikasikan ke benih untuk dilihat pengaruhnya. Uji mutu fisiologis menunjukkan bahwa perlakuan bakteri B8 (P24–AzL7), B9 (P24–AzL9), B15 (B28–AcCKB4), B20 (P24–AcCKB9), B23 (P24–AcCKB20), dan B24 (P24– AcCKW5) mampu meningkatkan indeks vigor benih. Perlakuan B23 juga mampu meningkatkan bobot kering kecambah normal. Percobaan di lapang menunjukkan bahwa aplikasi dosis 100% pupuk N-P nyata meningkatkan tinggi tanaman dan jumlah daun dibandingkan kontrol. Aplikasi bakteri nyata meningkatkan tolok ukur vigor benih namun belum mampu meningkatkan pertumbuhan vegetatif tanaman jagung hingga umur empat MST.
Keyword: Actinomycetes, Azotobacter, Isolasi, Mutu fisiologis benih

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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