Judul: Potensi Bacillus sp. Galur G3, Bacillus firmus E65, dan bakteri metanotrof sebagai penghambat pertumbuhan patogen Xanthomonas oryzae pv. oryzae dan Rhizoctonia solani
Abstrak: The use of bacilli and methanotropic bacteria as biocontrol agents for rice bacterial pathogens of X. oryzae pv. oryzae and R. solani can enhance rice production and reduce methane emission from rice fields. Some of methanotrophs had nitrogen fixation activity. Antagonism methods was tested to determine the ability of two bacilli species (Bacillus sp. G3 and B. firmus E65) and two methanotrophs (BGM 9 and SKM 14) in inhibiting growth of X. oryzae pv. oryzae and R. solani and inhibition between the two groups of bacteria. Methanotrophs (BGM 9 and SKM 14) inhibited growth of X. oryzae pv. oryzae with inhibition index (IP) of 2,27 and 2,79 respectively. Bacillus sp. G3, B. firmus E65 and SKM 14 isolates inhibited growth of R. solani with inhibition index of 0.63, 0.64, and 0.56 respectively. B. firmus E65 inhibited growth of methanotrophs (BGM 9 and SKM 14) and R. solani. Formulation of biocontrol agents containing Bacillus sp. G3 and methanotrophs (BGM 9 and SKM 14) can be done because there was no antagonism among the three bacteria. However the combination of B. firmus E65 and the metanotrophs should not be done in one formulation because of the antagonism between B. firmus E65 and the metanotrophs.
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Judul: Potensi Beberapa Bakteri Penghambat Pertumbuhan Xanthomonas oryzae pv. oryzae Penyebab Penyakit Hawar Daun Bakteri pada Tanaman Padi
Abstrak: Bacterial leaf blight (BLB) disease caused by plant pathogenic bacteria Xanthomonas oryzae pv. oryzae (Xoo) could lead to death of rice plants. Control of plant pathogenic bacteria can be performed using biological control agents. The aim of this research was to study the inhibitory ability of eight isolates of biocontrol bacteria against Xanthomonas oryzae pv. oryzae (Xoo) under greenhouse conditions. Isolates of biological agents used in the study were obtained from IPB Culture Collection (IPBCC), Department of Biology, IPB and microbial gene bank collection of Indonesian Center for Agriculture Biotechnology and Genetic Resources (BB Biogen), consisting of Pseudomonas aeruginosa C32a and C32b, P. fluorescens ATCC 13525 Pf , Serratia marcescens E31, Bacillus sp. I.5, B. cereus I.21 and II.14, and B. firmus E65 isolates. The methods used in the research i.e. hypersensitivity test, antagonistic test of biocontrol bacteria to Xoo, and in vivo application of biological agents in the greenhouse condition. Hypersensitivity test on tobacco plants using C32a and C32b inoculums showed characteristics of slightly leaf yellowing but did not cause necrosis. Injection using Xoo inoculum showed necrosis on tobacco leaves. Antagonist isolates i.e. C32a, C32b, Pf, I.21, and I.5 showed inhibitory activity against Xoo, whereas others isolates did not show inhibitory activity. In greenhouse experiments IR 64 rice plants were sprayed with biological control agents (107cfu/ml) at 7 days, 14 days, 28 days, and 42 days after planting. The results showed that C32a isolate could suppress better the lesion length of BLB than that of chemical control (copper sulphate). Growth measurement of rice plants were assessed on plant height, number of tillers, panicle number and grain weight. Rice plants spraying treatment with isolates E65, E31, C32a, C32b, I.21, Pf, and I.5 showed no difference with control of sterile distilled water. Spraying with each suspension isolate of I.21, E31, C32a, Pf, and C32b indicated no different in the panicle number, in addition rice production was higher in C32a, Pf, C32b, and I.21 treatments. Spraying with C32a isolates produced the highest grain production compared with that of other isolates.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh.
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.