Judul: The Potential of Forest Litter Penicillium and Trichoderma on IAA Production in Meranti Leaves Compost
Abstrak: Environmental manipulation through utilization of forest litter combined with microbial inhabiting rhizosphere is applied to achieve sustainable, prospective and healthy meranti (Shorea spp.) forest. Penicillium IPBCC 09 622 (SI1) and Trichoderma IPBCC 09 620 (SI2) originated from Dipterocarp litter were known to be able to reduce C/N ratio of Dipterocarp litter as well as produce IAA (Indole-3-Acetic Acid) in vitro. This study is aiming to assess the potential of these two fungi as a single (SI1, SI2) or their consortium (SI3) inoculants in producing IAA in meranti leaves compost. The compost was consisted of a mixture of meranti leave litter (83%), rice bran (15%) and urea (2%) at 60% moisture content. About 100 g of this mixture were placed in each polybag and steamed at 104oC for 30 minutes. The mixture were then inoculated with fungal biomass (SI1, SI2, or SI3) and then kept for 4 months. Uninoculated compost (SI-), steamed compost containing 4 ppm IAA synthetic (SA), and unsteamed and uninoculated compost (S-I-) were used as control. Each treatment had 3 replications. Observation was done monthly on population of Penicillium and Trichoderma, C/N ratio, water content (WC), organoleptic (color, texture and smell) and temperature (t) of the compost. At the end of decomposting period, minerals P, K, Ca and Mg, weight loss, decomposition rate analyses and bio-assay using shoot cutting of meranti tembaga (Shorea leprosula) were done. Observation indicated that Penicillium did not survive, but Trichoderma survived throughtout decomposition period. Penicillium did not have lignases, while Trichoderma only had tyrosinase. Fungal contamination occured during composting periods in all compost. About 10 fungal species were isolated in which Trichoderma was dominant. This contamination might effect to the overall research result. C/N ratio, WC and t content fluctuated between 15.93-45.47, 12.88-67.31% and 26-30.33oC respectively. At the end of composting period, C/N ratio was 15.93-18.53, WC was 26.55-50.94%, t was 29.67-30.33oC and minerals (P, K, Ca and Mg) content were 0.27-0.39%, 0.32-2.58%, 0.67-1.34%, 0.26-0.94%, respectively. Weight loss and decomposition rates was low, approximately 2.33-10.67% and 0.0058-0.028/yr respectively. The color, texture and smell of the compost did not meet the criteria SNI no. 19-7030-2004, while the C/N ratio and WC met SNI criteria. IAA production more were higher if the compost were inoculated with Trichoderma or it was infested by Trichoderma. IAA varied betwen 0.17-10.91 ppm depending on treatments. IAA detected using HPLC (high performance liquid chromatography) was slightly lower than those obtained from Salkowsky reagent. At the end of the composting, the compost was mixed with sterilized soil (1:1) and used for planting media of stem cutting. Bio-assay indicated that only 0.00-13.33% shoot cuttings of meranti tembaga showed root initiation depending on the composts. In conclusion Penicillium was not a potential agent, but Trichoderma was potential for IAA production in meranti leaves litter compost.
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Judul: Potensi konsorsium isolat bakteri dekomposer dan penghasil IAA untuk memacu pertumbuhan kacang hijau
Abstrak: The agricultural product has increased rapidly, so it affects not only agricultural waste but also agricultural byproducts, such as straw and corn leaves. The agricultural byproducts can be utilized to be organic fertilizer. It needs microorganism to make organic fertilizer through decomposition process. One of this microorganism is cellulolitic bacteria. Cellulolitic bacteria that produced IAA can be used for composting and inducing plant growth. The objective of this research is to know the ability of isolate bacteria in decomposing organic matter and synthesing IAA to induce plant growth. Miller method was used to measure the activity of cellulase enzyme and Salkowski reagent was used to measure the IAA concentration of both single and consortium bacteria. The parameters of decomposition were the percentage of final weight, the percentage of C-organic, and the percentage of N-total. Biossay qualitative method was used to identify the presence of IAA in litter. Isolate K resulted the highest activity of cellulase enzyme with using CMC substrat and also had activity in avicel and filter paper substrat. Isolate C11-1 and C11-1+H+ K resulted the highest IAA concentration. The result of decomposition showed that isolate C11-1+H+K had the lowest percentage of final dry weight. The litter that decomposed with C11-1+H tended to induce plant growth higher than others, it might that this consortium have the certain IAA concentration to induce plant height.
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Judul: Penyelesaian model mobil pengikut pada jalan melingkar
Abstrak: Arus lalu-lintas merupakan salah satu fenomena nyata yang dapat dideskripsikan melalui pemodelan matematika sebagai model dinamik kkontinu dengan sebuah sistem persamaan diferensial biasa. Terdapat dua buah jenis model makroskopik dan model mikroskopik. Model makroskopik memformulasikan arus lalu-lintas yang terjadi pada sejumlah besar kendaraan. Model mikroskopik digambarkan oleh sebuah model yang disebut model mobil pengikut (car follow model).
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