Judul: Potensi cendawan asal serasah tanaman hutan sebagai penghasil IAA (Indole--3-Acetic Acid) dan sebagai dekomposer
Abstrak: Silvikultur intensif merupakan salah satu program untuk mencapai hutan Indonesia sehat, prospektif dan lestari. Komponen silvikultur intensif salah satunya adalah pemanfaatan serasah tanaman hutan dan mikrobanya untuk menunjang pertumbuhan bibit tanaman. Hal tersebut dapat didukung dengan mengkaji berbagai potensi mikroba untuk meningkatkan pertumbuhan bibit tanaman. Penelitian dilakukan untuk mengkaji kemampuan cendawan yang berpotensi menghasilkan ZPT, khususnya IAA secara in vitro dan sekaligus sebagai dekomposer. Penelitian idi dilakukan dalam tiga tahap yaitu penapisan isolat berpotensi sebagai penghasil IAA, uji kemampuan isolat terpilih dalam mendegradasi selulosa dan uji kemampuan isolat terpilih dalam mendekomposisi serasak.
Keyword: 

Judul: Potensi kapang asal serasah tanaman hutan sebagai penghasil asam indol asetat dan toleransinya terhadap kondisi asam
Abstrak: Microorganism in soil and forest litter plays an important role in maintaining the health of the soil such as decomposer, nutrient transformation agent, mineral solubilizer, and also as hormones producer. One of the hormones produced by microorganism including molds is indole-3-acetic acid (IAA). Utilization of IAA producer molds that tolerance to acid conditions may increase the production of industrial forest in acid soil and improve the vigour of plantling stock material originated from stem cutting. This study was aimed to assess the potential of forest litter molds of IPBCC (Institut Pertanian Bogor Culture Collection) collection as IAA producers and their tolerance to acid conditions. The ability of fifty-one forest litter molds from Katingan and Tarakan to produce IAA was screened in Czapek Dox medium and was determined by Patten and Glick method using Salkowski reagent. According to Patten and Glick method, the forest litter molds from Katingan produced IAA (1.92±0.26 ppm) were higher than those of Tarakan (1.08 ± 0.14 ppm). The production of IAA by static incubation (2.72±0.89 ppm) was higher than those of shaking incubation (1.92 ± 0.26 ppm). The production of IAA on the forest litter molds from Katingan (63.16%) were not influenced by the storage process. Four out of fifty Katingan’s molds were selected for IAA production, those were Acremonium sp. IPBCC 07.548 (3.52±0.46 ppm), Aspergillus ornatus IPBCC 07.554 (4.50±0.92 ppm), Gliocladium deliquescens IPBCC 07.543 (2.23±0.38 ppm), and Penicillium notatum IPBCC 07.555 (5.06±0.46 ppm). IAA and its biomass productions were influenced by pH of the medium. These forest litter molds were considered to be acid tolerance. The pH optimum for their growth and IAA production were 5.5. These molds showed no antagonistic response to each other. The IAA production from these molds in consortium (7.22±1.33 ppm) were better than its single culture (4.43±1.53 ppm). High performance liquid chromatography assay indicated that there was only one type of IAA with retention time 7.1.
Keyword: 

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.
Keyword: