Judul: Sortation and Electrotherapy of Rice Seeds that Carry Xanthomonas oryzae pv. oryzae and Burkholderia glumae
Abstrak: Padi merupakan tanaman pangan utama dan sumber karbohidrat penting di Indonesia. Jumlah konsumsi beras di Indonesia semakin meningkat, sedangkan produksi padi menunjukkan grafik yang fluktuatif. Keberadaan patogen pada kulit benih, embrio, dan endosperm benih dapat menurunkan mutu benih padi. Deteksi bakteri terbawa benih padi dilakukan melalui uji Gram menggunakan KOH 3% dan pewarnaan bakteri serta uji hipersensitivitas menggunakan tanaman indikator tembakau. Bakteri Burkholderia glumae dan Xanthomonas oryzae pv. oryzae ditemukan pada padi varietas Inpari 42, Ciherang, dan Pandan Wangi di Desa Sukaresmi, Kecamatan Tamansari Kabupaten Bogor. Perlakuan sortasi benih padi tanpa gejala dari yang bergejala memberikan mutu benih lebih baik yaitu bobot 1000 butir, viabilitas dan pertumbuhan padi. Benih padi bergejala memiliki bobot 1000 butir, viabilitas dan pertumbuhan padi yang lebih rendah dari pada sampel padi tanpa gejala atau sampel campuran tanpa gejala dan bergejala. Perlakuan elektroterapi dengan parameter arus listrik 12 V DC dan 1 A selama 30 menit dalam larutan elektrolit NaCl 1 M berpengaruh nyata terhadap daya kecambah benih bergejala pada varietas Inpari 42, tetapi tidak berpengaruh nyata terhadap benih varietas Ciherang dan Pandan Wangi. Perlakuan elektroterapi pada benih bergejala berpengaruh terhadap panjang tajuk tanaman varietas Ciherang, tetapi tidak berpengaruh terhadap panjang tajuk tanaman Inpari 42 dan Pandan Wangi., Rice is the main food crop and an important source of carbohydrates in Indonesia. The amount of rice consumption in Indonesia is increasing, while rice production shows a fluctuating graph. Rice production is affected by the physiological, physical, and genetic quality of its seeds. The presence of pathogens in the part of including coat, embryo, and seed endosperm can reduce seed quality. The bacteria carried by rice seeds was detected through Gram test using KOH 3% and Gram staining and hypersensitivity reaction (HR) test using tobacco as indicator plants. Bacteria Burkholderia glumae and Xanthomonas oryzae pv. oryzae were found in rice varieties Inpari 42, Ciherang, and Pandan Wangi in Sukaresmi Village, Tamansari District, Bogor Regency. The sortation treatment gave symptomless rice seed samples better seed quality, namely weight of 1000 grains, viability, and seedling growth than those symptomatic seed samples. Symptomatic rice seeds have a lower weight of 1000 grains, seed viability, and plant growth than symptomless seed samples or mixed samples of both symptomless and symptomatic seeds. Electrotherapy treatment including electric current at 12 V DC, 1 A for 30 minutes in 1 M NaCl electrolyte solution significantly affects the germination of symptomatic seeds of the Inpari 42 variety but does not significantly affect the seeds of the Ciherang and Pandan Wangi varieties. Electrotherapy treatment on symptomatic seeds affects the length of the plant crown of the Ciherang variety but does not affect the length of the plant crown of the Inpari 42 and Pandan Wangi varieties.
Keyword: Electric current, Seed-borne bacteria, Seed treatment, Seed viability

Judul: Determination and Identification Seed-Borne Fungi from Rice Seeds.
Abstrak: Padi merupakan tanaman pangan penting di Indonesia yang tidak terlepas dari gangguan hama dan penyakit tumbuhan. Beberapa patogen tular benih dapat menyebabkan perkecambahan abnormal, kematian benih, dan menjadi sumber inokulum yang dapat menimbulkan epidemi penyakit di lapangan. Mengingat pentingnya dampak tersebut, dilakukan suatu studi yang bertujuan untuk mendeteksi cendawan yang terbawa benih padi dengan metode blotter test yang termodifikasi dengan dua perlakuan (aplikasi disinfektan dan kontrol) serta 4 ulangan. Dalam studi ini digunakan benih uji varietas Baroma dan IR Nutri Zinc asal Kebun Percobaan Muara, BB Padi, Bogor, Jawa Barat. Data yang diperoleh dianalisis ragam dan faktor yang berpengaruh nyata dilakukan uji lanjut Tukey pada α = 5%. Hasil studi menunjukkan bahwa persentase daya berkecambah benih varietas IR Nutri Zinc lebih tinggi dibandingkan dengan varietas BAROMA. Perlakuan sterilisasi permukaan dengan NaOCl 1% mampu mengeliminasi kontaminan pada benih. Cendawan yang terdeteksi sebagai kontaminan tersebut adalah Aspergillus spp. Tingginya persetase kontaminan Aspergillus menyebabkan tidak terdeteksinya cendawan patogen penting lainnya pada benih padi., Rice is an important food crop in Indonesia that cannot be separated from pests and plant diseases. Several seed-borne pathogens can cause abnormal germination, seed mortality, and become a source of inoculum that can cause disease epidemics in the field. Considering the importance of this impact, this study aimed to detect the seedborne fungi carried by rice seeds using a modified blotter test method with two treatments (disinfectant and control) and 4 replications. This research was conducted using Baroma rice seeds and IR Nutri Zinc rice seeds from Muara Experimental Garden, Indonesia Center for Rice Research, Bogor, West Java. Data were analyzed of variance with Tukey test with α = 5%. The results showed that the germination of IR Nutri Zinc variety was higher than BAROMA variety. Surface sterilization treatment with 1% NaOCl was able to eliminate seed contaminants as indicated by a lower percentage of infection. The fungi detected as contaminants were Aspergillus spp. The dominance of Aspergillus causes other main fungi that can't be detected in rice seeds.
Keyword: Aspergillus, blotter test, epidemi, kontaminasi

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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