Judul: Pigmentation Patterns and Photosynthesis of Variegated Caladium as Ornamental Plants at Different Shading Levels
Abstrak: Caladium atau keladi merupakan anggota famili Araceae yang memiliki warna dan corak daun beragam yang dikenal dengan variegata. Penelitian ini bertujuan untuk menganalisis hubungan pola pigmentasi dan luasan variegata dengan anatomi, kandungan klorofil dan laju fotosintesis pada tanaman hias daun variegata dari genus Caladium, dengan perlakuan naungan 0 dan 70% di teras bangunan Departemen Biologi IPB pada paparan sinar matahari pagi langsung. Tanaman yang digunakan yaitu tujuh tipe keladi yang berbeda. Metode yang digunakan meliputi pengukuran intensitas cahaya, pencocokan warna daun, pengukuran laju fotosintesis menggunakan Li-6400 portable photosynthesis system pada tingkat PPFD (Photosynthetic Photon Flux Density) 100, 400, dan 800 µmol m-2 s-1; analisis kadar pigmen, serta pengamatan stomata dan ketebalan daun. Warna daun dan bercak variegata pada intensitas cahaya yang tinggi menunjukkan hasil lebih cerah, memiliki ukuran daun yang lebih kecil dan tebal dengan luas bercak lebih banyak. Kandungan klorofil, karotenoid, dan antosianin yang tinggi ditemukan pada mayoritas tanaman naungan 0%. Kandungan pigmen tersebut berpengaruh terhadap fotosintesis, dan laju fotosintesis (Pn) meningkat pada tanaman seiring dengan meningkatnya intensitas cahaya. Paparan cahaya langsung di pagi hari berpengaruh terhadap tingginya kerapatan stomata dan luasan daun. Hal ini menunjukkan bahwa beberapa keladi hias tumbuh optimal pada kondisi tanpa naungan dengan rata-rata intensitas cahaya pagi berkisar 30.000-40.000 lux., Caladium is a member of the Araceae family that has leaves with various colors and patterns, known as variegated leaves. This study aimed to analyze the relationship of pigmentation pattern and variegated area with anatomy, chlorophyll content and photosynthetic rate in variegated leaf ornamental plants of Caladium, under 0 and 70% shade in a terrace Department of Biology IPB university, receiving morning direct sunlight exposure. The plants used were seven different types of Caladium. The observations included measurement of light intensity, leaf color, photosynthetic rate using a Li-6400 portable photosynthesis system at PPFD (Photosynthetic Photon Flux Density) levels of 100, 400, and 800 µmol m-2 s-1; pigment content analysis, as well as stomatal density, and leaf thickness. Leaf color and spotting of variegates at high light intensity showed brighter results, having smaller but thicker leaf, with more spotting area. High chlorophyll, ß-carotene and anthocyanin contents were found in the majority of 0% shaded plants. The content of these pigments affected photosynthetic rate (Pn) in the plants which it increased as light intensity increased. Exposure to direct sunlight in the morning resulted in higher stomatal density and leaf area. This shows that some ornamental caladiums grow optimally without shading at average morning light level of 30.000-40.000 lux.
Keyword: anthocyanin, carotenoids, chlorophyll, light intensity, shading

Judul: Morphophysiological and Anatomical  Responses of Sun and Shade Plants to Sunlight Intensity Stress
Abstrak: Setiap tumbuhan mempunyai kebutuhan intensitas cahaya tertentu. Apabila tumbuhan menerima intensitas cahaya yang tidak sesuai dengan kebutuhannya, akan menyebabkan pertumbuhan dan perkembangan yang berbeda. Tujuan penelitian ini adalah untuk mengetahui perbedaan ciri morfologi, fisiologi, dan anatomi tanaman suka sinar matahari (Catharanthus roseus) dan suka teduhan (Spathiphyllum sp.) yang ditanam pada berbagai tingkat intensitas cahaya, yakni naungan 0% (sinar matahari penuh), 50% dan 95%. Tanaman dinaungi menggunakan paranet berkerapatan berbeda di Kebun Percobaan Leuwikopo, Kampus Dramaga, IPB University. Analisis fotosintesis dilakukan menggunakan Li-6400 portable photosynthesis system dengan Photosynthetic Photon Flux Density (PPFD) 2000, 800 dan 50 µmol/m/s. Biomassa terbesar terjadi pada naungan 50% untuk kedua jenis tanaman, dan menurun pada naungan yang lebih tinggi pada tapak dara, dan kondisi sinar matahari penuh pada peace lily. Kandungan klorofil, luas, dan sudut daun meningkat seiring dengan penambahan naungan. Perlakuan naungan tidak berpengaruh nyata terhadap kadar air total kedua jenis tanaman. Asimilasi CO2 (Pn) terbaik terukur dengan PPFD 800 dan 2000 µmol/m/s, pada tanaman naungan 50%, meskipun tidak berbeda nyata dengan tanaman naungan 0% dan 95%. Hal ini menunjukkan perlakuan naungan tidak menyebabkan kerusakan perangkat fotosintesis. Struktur jaringan daun terbaik (rapat) dimiliki tapak dara naungan 0% dan peace lily naungan 95%., Plant species have certain requirement for light intensity, therefore if plants receive inappropriate light intensity, it will cause adverse growth and development. The aim of this research was to observe differences in the morphological, physiological, and anatomical characteristics of sun plant periwinkle (Catharanthus roseus) and shade plant Spathiphyllum sp. grown at different levels of light intensity, i.e., 0% shade (full sunlight), 50% shade, and 95% shade. Light intensity treatment was provided by placing the plants under para-net with different density in Leuwikopo Experimental Garden, Dramaga Campus, IPB University. Photosynthesis analysis was carried out using the Li-6400 portable photosynthesis system, with Photosynthetic Photon Flux Density (PPFD) adjusted at 2000, 800 and 50 µmol/m/s. The largest biomass resulted in 50% shade for both types of plants, which decreased significantly by higher shading for periwinkle, while for peace lily it decreased under full sunlight. Chlorophyll content, leaf area and leaf angle increased with the intensed shade density. Shading treatment had no significant effect on total water content of both plant species. The best photosynthetic CO2 assimilation (Pn) measured with PPFD 800 and 2000 µmol/m/s occurred in the plants treated with 50% shading, even though not significantly different with the plants without shading and with 95% shading, suggesting that shading treatments did not cause the damage of photosynthetic apparatus. The most compact anatomical structure was shown by the periwinkle with 0% shading and the peace lily with 95% shading.
Keyword: Catharanthus roseus, chlorophyll, photosynthesis, shade, Spathiphyllum sp

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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