Judul: Perlakuan Agens Hayati untuk Mengendalikan Hawar Daun Bakteri, Meningkatkan Pertumbuhan Tanaman dan Produksi Benih Padi
Abstrak: Healthy rice seed (free of Xanthomonas oryzae pv. oryzae (Xoo)) could be produced by prevention of Xoo infection from the seed source and the plant. Xanthomonas oryzae pv. oryzae causes bacterial leaf blight (BLB) in rice. The objectives of the research were to evaluate biological agent treatments in controlling BLB and increasing plant growth and seed production of rice. The research consisted of two parts. The first part was aim to obtain the rhizosphere and phyllosphere biological agents capable of controlling Xoo. The first experiment in the first part conducted to isolate the virulent Xoo. The second experiment was a retest for antagonism of rhizobacteria collection against the isolated Xoo which would be used in seed treatments. The third experiment was isolation and antagonism test of phyllosphere bacteria against Xoo to be used in spraying the plants. The second part of this study was the evaluation of biological agent treatment (seed treatment and plants spraying) effects in controlling BLB disease and improving plant growth and seed production. The first experiment was conducted in the greenhouse and the second one in the field using the same experimental design (randomized block design with two factors) and three replications. Seed treatments (first factor) consisted of negative control, positive control, streptomycin sulfate 0.2%, Pseudomonas diminuta A6 + Bacillus subtilis 5B, matriconditioning + streptomycin sulphate 0.2%, and matriconditioning + P. diminuta A6 + B. subtilis 5B. Spraying plants (second factor) consisted of untreated control, streptomycin sulphate 0.2%, biological agent F112, biological agent F198, and biological agent F57. The first experiment from the first part of these studies resulted virulent Xoo isolated from ooze. The second experiment confirmed that P. diminuta A6 + B. subtilis 5B indicated high antagonism against the Xoo. The third experiment produced phyllosphere isolates F112, F198, and F57 showing high antagonism against the Xoo. The first experiment in the second part of these studies showed that matriconditioning + P. diminuta A6 + B. subtilis 5B improved seed germination from 93.6% to 96.9%, plant height from 70.9 cm to 76 cm, plant dry weight from 1.35 g to 1.91 g as compared to positive control. Spraying plants using biological agent F112 increased plant dry weight from 1.40 g to 1.78 g as compared untreated control. Meanwhile, matriconditioning + P. diminuta A6 + B. subtilis 5B followed by spraying plants with biological agent F112 reduced the BLB severity. The second experiment showed that matriconditioning + P. diminuta A6 + B. subtilis 5B improved seedling dry weight. Matriconditioning + P. diminuta A6 + B. subtilis 5B and spraying plants with biological agents F112 controlled BLB and increased plant growth. However, all treatments were not able to increase healthy seed production, these may be due to population of the biological agents applied was not optimum yet.
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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: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf