Judul: Determining the Right Harvest Time of Cucumber  (Cucumis sativus L.) Based on Heat Units
Abstrak: Mentimun merupakan sayuran yang sangat populer dan banyak dikonsumsi masyarakat Indonesia. Salah satu kendala dalam penanganan pasca panen mentimun adalah penentuan umur panen yang kurang tepat. Penelitian ini bertujuan menentukan waktu panen yang tepat untuk menghasilkan buah mentimun yang berkualitas baik sesuai kriteria pasar dengan akumulasi satuan panas. Penelitian dilaksanakan di Kebun Percobaan Leuwikopo, IPB, Bogor dan Laboratorium Pascapanen IPB pada bulan Februari sampai April 2024. Percobaan menggunakan rancangan kelompok lengkap teracak dengan empat ulangan dan satu faktor, yaitu umur panen (6, 8, 10, 12, dan 14 Hari Setelah Antesis (HSA)). Hasil penelitian menunjukkan terdapat pengaruh yang nyata antara umur panen dengan perkembangan biji, warna buah, bobot per buah, ukuran buah, kelunakan buah, padatan terlarut total, dan produktivitas. Umur panen mempengaruhi perkembangan biji, warna buah, bobot per buah, ukuran buah, kelunakan buah, padatan terlarut total, dan produktivitas. Akumulasi satuan panas sebesar 113 sampai 189 °C hari dengan umur panen 6 HSA sampai 10 HSA memberikan hasil yang optimum untuk mentimun konsumsi segar., Cucumber is a very popular vegetable and is widely consumed by Indonesians people. One of the obstacles in post-harvest handling of cucumber is the determination of an inappropriate harvest age. This study aims to determine the right harvest time to produce good quality cucumber fruit according to market criteria with the accumulation of heat units. The research was conducted at Leuwikopo Experimental Farm, IPB, Bogor and the Postharvest Laboratory of IPB from February to April 2024. The experiment used a Randomized Complete Block Design with four replications and one factor, namely harvest age (6, 8, 10, 12, and 14 Day After Anthesis (HSA)). The results showed that there was a significant influence between harvest age and seed development, fruit color, weight per fruit, fruit size, fruit softness, total soluble solids, and productivity. Harvesting age affects seed development, fruit color, weight per fruit, fruit size, fruit softness, total soluble solids, and productivity. Heat unit accumulation of 113 to 189 °C days with harvesting age of 6 HSA to 10 HSA gave optimum yield for fresh consumption cucumber.
Keyword: Kualitas, quality, antesis, fenologi, umur panen, anthesis, harvest time, phenology

Judul: Studi Fenologi dan Penentuan Masak Fisiologis Benih Mentimun (Cucumis sativus L.) Berdasarkan Unit Panas.
Abstrak: Tujuan penelitian ini adalah untuk mempelajari fenologi perkembangan bunga sampai menjadi buah dan mengetahui unit panas yang tepat untuk menentukan masak fisiologis benih mentimun (Cucumis sativus L.). Studi fenologi dilakukan sejak antesis sampai batas terakhir pemanenan. Unit panas tanaman diperoleh dari pengukuran suhu harian. Studi penentuan masak fisiologis benih mentimun menggunakan rancangan kelompok lengkap teracak satu faktor. Faktor percobaan adalah umur panen mentimun yang terdiri atas 20 taraf, yaitu 15 sampai 34 hari setelah antesis (HSA). Hasil menunjukkan, masak fisiologis benih mentimun varietas Vanesa dicapai pada umur panen 29 HSA dengan ciri-ciri warna kulit buah kuning, benih berwarna putih kecoklatan, dan biji mudah dilepas dari daging buah. Pada umur panen ini kadar air benih 41.5%, bobot kering benih 2.5 g, viabilitas benih maksimum (daya berkecambah 96%), serta vigor maksimun (indeks vigor 93.5% dan keserempakan tumbuh 96%). Unit panas benih mentimun varietas Vanesa saat masak fisiologis (29 HSA) adalah 979.80Cd.
Keyword: bobot kering benih, viabilitas, vigor

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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