Judul: Kandungan Prolin Dan Asam Askorbat Beberapa Spesies Hoya Dengan Tingkat Sukulensi Berbeda Pada Cekaman Kekeringan
Abstrak: Hoya merupakan tanaman epifit merambat yang memiliki tipe daun sukulen dan non sukulen. Hoya sukulen lebih memiliki sifat tahan terhadap kekeringan dibandingkan dengan Hoya non sukulen. Salah satu mekanisme pertahanan tanaman terhadap kekeringan adalah dengan mengakumulasi senyawa prolin dan asam askorbat. Penelitian ini bertujuan mengetahui pengaruh cekaman kekeringan terhadap kandungan prolin dan asam askorbat pada tanaman Hoya dengan tingkat sukulensi yang berbeda sebagai indikasi ketahanan terhadap kekeringan. Perlakuan cekaman dilakukan selama 28 hari terhadap empat spesies Hoya yaitu H. densifolia (non sukulen), H. bandaensis (semi sukulen), H. verticillata, dan H. latifolia (sukulen). Hasil menunjukkan bahwa cekaman kekeringan meningkatkan kadar prolin dan asam askorbat (ASA) pada spesies Hoya yang diuji. Hoya sukulen memiliki kadar prolin dan ASA yang lebih tinggi dibandingkan dengan Hoya non sukulen. Hoya verticillata (sukulen) memiliki peningkatan kandungan prolin dan ASA tertinggi saat tercekam kekeringan. Oleh karena itu H. verticillata merupakan spesies Hoya yang tahan kekeringan yang dicirikan dengan daun sukulen dan kadar prolin dan ASA yang tinggi.
Keyword: Hoya, asam askorbat, prolin, kekeringan, sukulen, non sukulen

Judul: Karakteristik Anatomi Daun beberapa Spesies Hoya spp. Bertipe Daun Sukulen serta Analisis Hubungan Kekerabatannya
Abstrak: Hoya (Hoya spp.) is an epiphyte or lithophyte vine or shrub. Hoya’s flower has beautiful unique shape and it is considered as original plant from Southeast Asia and surroundings. This plant has two type of leaf, succulent and non succulent. Succulent plant can adapt well in extreme condition, especially in dry period. Anatomy characters can be used to identify, classify, and determine plant relationship. The aims of this research were to identify anatomical character of succulent Hoya’s leaf and to determine their relationship. Ten exmined species Hoya spp. (H. diversifolia, H. latifolia, H. dolichosparte, H. bilobata, H. lacunosa, H. verticillata, H. purpureofusca, H. kuhlii, H. oblanceolata, and H. micrantha) showed anatomical similarity which was epidermal layer, hipodermal, mesophil, and the absence of sponge tissue at mesophil. However there were many diversities between specieses. Based on paradermal section of the leaf, stomata was only found on the abaxial side and have two type, individual stomata and both individual and stomatal cluster. Hoya diversifolia had the smallest stomatal size, while Hoya latifolia had the biggest. Hoya lacunosa had the lowest stomatal density, while Hoya bilobata had the highest. Hoya diversifolia, Hoya lacunosa, and Hoya oblanceolata had the lowest stomatal index, while Hoya bilobata had the highest. Observation on transversal section showed that Hoya purpureofusca had the lowest leaf thickness, while Hoya kuhlii had the highest. The hierarchical cluster analysis based on anatomical leaf character showed different patterns of relationship which diversed as three groups at relationship scale 15.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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