Judul: Soybean (Glycine max (L.) Merr.) Seed Sorting and The Relationship of Seed Size with Seed Quality
Abstrak: Kedelai merupakan komoditas palawija penting dan permintaan konsumsinya terus meningkat. Produktivitas kedelai nasional tergolong rendah sehingga belum mampu memenuhi permintaan nasional. Produksi kedelai nasional dapat ditingkatkan dengan penggunaan benih bermutu. Mutu benih sangat berkaitan dengan ukuran benih. Penelitian bertujuan menganalisis pengaruh ukuran benih terhadap mutu benih kedelai. Rancangan yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan faktor ukuran benih yang terdiri dari empat taraf yaitu ukuran besar, sedang, kecil, dan campuran, serta dilakukan pengulangan sebanyak tiga ulangan. Varietas Grobogan ukurannya relatif lebih besar dibandingkan varietas Demas 1. Benih Grobogan dengan diameter ≥ 0,67 cm dikategorikan benih ukuran besar, sedangkan diameter ≤ 0,61 cm dikategorikan benih berukuran kecil. Benih Demas 1, ukuran besar memiliki diameter ≥ 0,50 cm dan benih ukuran kecil memiliki diameter ≤ 0,47 cm. Ukuran benih berpengaruh nyata terhadap bobot kering kecambah normal varietas Grobogan dan Demas 1, dan pengaruh nyata terhadap indeks vigor benih kedelai varietas Demas 1. Ukuran benih kecil Demas 1 menunjukkan indeks vigor dan BKKN tertinggi, sebaliknya ukuran benih besar Grobogan menunjukkan BKKN tertinggi. Ukuran benih kecil menunjukkan daya hantar listrik lebih rendah. Benih ukuran kecil menunjukkan kemunduran vigor yang relatif lebih rendah setelah pengusangan cepat. Laju imbibisi dipengaruhi luas penampang yang dibuktikan dengan varietas Grobogan yang memiliki ukuran lebih besar memiliki laju imbibisi lebih besar dibandingkan benih kedelai Demas 1. Pemilahan benih kedelai mampu memisahkan benih menjadi empat kategori, dan benih berkategori kecil memiliki viabilitas, vigor, dan vigor daya simpan lebih tinggi., Soybean is an important grain commodities and its consumption demand increases, yearly. Soybean productivity in Indonesia is recorded low, and could not suply the national demand. Soybean production could be increased by encourage the use of seed high-quality. Seed quality closely correlates to seed size. The research was aimed to obtaine the seed size effect on viability and vigor of soybean seed. A Randomized Completely Design with three replications was applied, and the factor was seed size that consist of four sizes, i.e. large, immadiate, medium, small, and mixture. Grobogan variety had a larger size than Demas 1. Seed size chategorizes on Grobogan were ≥ 0,67 cm (large) and ≤ 0,61 cm (small), while on Demas 1 were ≥ 0,50 cm (large) and ≤ 0,47 cm (small). The seed size has a significant effect on dry weight of normal seedling (DWNS) both variety, and vigor index of Demas 1. Small seed resulted the highest vigor index and DWNS on Demas 1, contrary, large seed showed the highest DWNS on Grobogan. Small seed also resulted the lowest electry conductivity more than other sizes. Small seed manifested the lower vigor detioration after accelarate ageing test, relatively. Imibition rates exteremly affected by cross-sectional area of the seed. It was evidenced of Grobogan that chategorized was large seed, where its imbibition rates higher than Demas 1. Sortation of soybean seed could separated the seed in four size groups, i.e. small, medium, large, and mixture. Small seed indicated the high viability, vigor, and seed longevity-vigor.
Keyword: accelerated aging test, electricity conductivity, imbibition rates, viability, vigor

Judul: Soybean (Glycine max (L.) Merrill) Seed Longevity Prediction Using Several Vigour Test Methods
Abstrak: Kedelai (Glycine max L.) merupakan salah satu komoditas penting di Indonesia. Metode yang tepat untuk menduga viabilitas berdasarkan nilai daya berkecambah setelah melewati periode tertentu dalam penyimpanan sangat penting untuk memastikan benih kedelai yang sampai ke tangan konsumen (petani) masih memiliki mutu yang baik. Penelitian ini bertujuan mendapatkan satu metode yang mampu menduga daya simpan benih kedelai. Penelitian dilaksanakan di Laboratorium Ilmu dan Teknologi Benih IPB. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) terdiri dari faktor lot benih yang tersarang pada periode simpan. Faktor pertama adalah lot benih kedelai yang terdiri atas 6 taraf yaitu Dena 1 (tahun 2019), Devon 1 (tahun 2019), Detap 1 (tahun 2019), Anjasmoro (tahun 2019), Gepak Kuning (tahun 2019), dan Argomulyo (tahun 2019). Faktor kedua adalah periode simpan dengan 7 taraf yaitu 0, 1, 2, 3, 4, 5 dan 6 bulan. Benih kedelai dari berbagai varietas yang digunakan sebagai lot benih memiliki daya berkecambah awal berkisar 84,25% - 94,25%, dapat mempertahankan viabilitasnya hingga 73,50% - 79,50% setelah disimpan selama 6 bulan. Kondisi kadar air sebelum penyimpanan berkisar 8,51% - 9,94% dan 8,41% - 9,51% pada 6 bulan penyimpanan. Kondisi suhu dan RH ruang penyimpanan berkisar 20,2 ± 2 ºC dan 49 ± 2% dengan kemasan benih berupa plastik polypropylene (PP) 0,8 mm. Ekstrapolasi pada grafik penurunan daya berkecambah menunjukkan benih kedelai yang diuji memiliki variasi daya simpan antara 8,5 – 11,8 bulan untuk penurunan hingga daya berkecambah 65% atau 7,0 – 8,9 bulan untuk penurunan hingga daya berkecambah 70%. Radicle emergence (RE) yang diamati pada 42 jam merupakan tolok ukur yang paling potensial untuk menduga daya simpan benih kedelai dengan nilai koefisien korelasi sebesar 0,6033 untuk menduga daya simpan hingga daya berkecambah menjadi 65% dan 0,6442 untuk menduga daya simpan hingga daya berkecambah menjadi 70%., Soybean (Glycine max L.) is one of the important commodities in Indonesia. The right method to estimate viability based on the value of germination after a certain period of storage is very important to ensure that soybean seeds that reach consumers (farmers) still have good quality. This study aims to obtain a method that can estimate the seed longevity of soybean. The research was carried out at the Seed Science and Technology Laboratory of IPB. This study used a completely randomized design (CRD) consisting of several nested seed lots in the storage period. The first factor is the soybean seed lot which consists of 6 levels, namely Dena 1 (in 2019), Devon 1 (in 2019), Detap 1 (in 2019), Anjasmoro (in 2019), Gepak Kuning (in 2019), and Argomulyo (in 2019). The second factor is the storage period with 7 levels, namely 0, 1, 2, 3, 4, 5, and 6 months. Soybean seeds of various varieties used as seed lots have initial germination rates ranging from 84.25% - 94.25%, can maintain their viability up to 73.50% - 79.50% after being stored for 6 months. Conditions of water content before storage ranged from 8.51% - 9.94% and 8.41% - 9.51% at 6 months of storage. The temperature and RH conditions of the storage room ranged from 20.2 ± 2 ºC and 49 ± 2%
Keyword: expired date, radicle emergence, rapid aging, storage, viability

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: