Judul: Karakterisasi Aksesi Padi Beras Merah dan Hitam (Oryza sativa L.)
Abstrak: Red rice and black rice has more advantage than white rice, including higher nutrient content than white rice. Red and black rice has anthocyanin, a substance causing the colors on the rice pericarp. Most of the red rice and black rice that has been cultivated are landrace cultivars. The local varieties can be one source of characters for plant breeding. Characterization was done to find out the potential characters that contained in the landraces. Plant material used were local rice accessions 22 red and black rice varieties with Aek Sibundong as check. The research results showed that local red and black rice accessions gave very significant effect on the observed variables . Accessions that has the potential to be developed are Sidrap (G7), Malang (G9), Pasaman (G13), Temanggung (G21), Purworedjo (G23), Mesuji (G25), Garut (G26), Meulaboh (G27), and Nisam (G34). They achieved productivity more than 4 ton.ha-1.
Keyword: red rice, landrace cultivar, characterization, accession

Judul: Analisis Keragaman dan Korelasi Antar Karakter Biji 204 Aksesi  Padi (Oryza sativa L.) Lokal Indonesia
Abstrak: Bentuk dan ukuran biji padi (Oryza sativa L.) lokal Indonesia menjadi karakteristik agronomis penting, sehingga menjadi target pemuliaan. Penelitian ini mengkaji keragaman 204 koleksi biji padi lokal yang dilanjutkan dengan studi korelasi antar karakter. Data fenotipe dikumpulkan dengan pendekatan citra beresolusi tinggi dan diekstrak menggunakan software SmartGrain, meliputi panjang (L), lebar (W), luas (AS), perimeter (PL), rasio panjang-lebar (LWR), dan sirkularitas (CS). Bulir biji menunjukkan variabilitas sedang hingga tinggi, dengan LWR menjadi karakter paling beragam di antara 204 aksesi yang diteliti. Uji korelasi mengungkapkan karakter PL dan L memiliki koefisien korelasi positif tertinggi, sedangkan karakter LWR dan CS memiliki korelasi negatif tertinggi. Berdasarkan karakter LWR, terdapat tiga tipe bentuk gabah dan beras yaitu biji berukuran sedang adalah yang paling umum dari 204 koleksi biji yang diteliti, sedangkan biji ramping dan agak bulat lebih sedikit. Penelitian ini adalah studi pertama yang melaporkan tentang variasi dan hubungan antar karakter biji padi lokal Indonesia, yang diharapkan dapat berkontribusi dalam menentukan aksesi pilihan terbaik dalam program pemuliaan untuk meningkatkan produktivitas padi., The shape and size of local Indonesian rice (Oryza sativa L.) seeds are important agronomic traits, which can be a target for breeding program. The research examines the diversity of 204 collections of local rice seeds and their correlations. Phenotypic data were collected using a high-resolution image approach and extracted using SmartGrain software, including length (L), width (W), area (AS), perimeter length (PL), length-width ratio (LWR), and circularity (CS). Seed grains exhibited moderate to high variability with LWR being the most diverse character among the 204 accessions. The correlation analysis among seed characters signifies that the characters PL and L show the highest positive correlation, while LWR and CS had the highest negative correlation coefficient. Based on LWR, there are three grain and rice shapes were observed, i.e., slim, medium, dan round-sized seeds, with medium-sized seeds being the most common. This study is the first to report on variations and correlations of local Indonesian rice seed characters, which expect to contribute to selection criteria in breeding programs aimed at increasing rice productivity.
Keyword: fenotiping digital, pemuliaan, SmartGrain, variabilitas

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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