Judul: Studi Keefektifan Formulasi Spora Bacillus Subtilis Sebagai Agens Pengendali Hayati Penyakit Hawar Daun Bakteri dan Hawar Pelepah Serta Pemicu Pertumbuhan Pada tTanaman Padi:
Abstrak: In controlling rice diseases, most farmers still rely on chemical pesticide as the solution. However, because of high cost and negative effects of chemical pesticide, biocontrol is one of alternative solutions. Bacillus subtilis is a model of biocontrol agents to control many plant diseases, because its ability to produce antimicrobial and plant growth promoting substances. This research aimed to examine the effectiveness of Indonesian isolate of B. subtilis spore formulation through seed treatment and foliar spray with different frequencies and concentrations to control bacterial leaf blight (Xanthomonas oryzae pv. oryzae) and sheath blight (Rhizoctonia solani) diseases of rice. The influence of the formulation application to plant growth and other microbes was evaluated. The experiment was conducted in greenhouse and field with factorial experimental design. Seed treatment, concentration and frequency of application and its interaction effectively suppressed bacterial leaf blight and sheath blight diseases, increased plant growth and reduced yield loss. The concentration at 2% is recommended for applying the formulation. The interval of application at 1 and 2 week showed equal effect to disease suppression and increased yield. Application of B. subtilis spore formulation increased yield of Ciherang, Cisantana, and Sintanur as much as 26,3%, 18,5%, and 15,4% respectively. Application of the formulation gave no significant effect to microbe diversity in the field.
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Judul: Keefektifan Formulasi Cair dan Pasta Ralstonia pickettii untuk Mengendalikan Penyakit Hawar Pelepah pada Padi
Abstrak: Rice is the most important food crop in Indonesia. Sheath blight disease is one of inhibiting factors in rice productivity improvement. Ralstonia pickettii has been reported as potential biological control agent of sheath blight. R. pickettii formulation technologies should be developed to increase its durability and effectiveness in suppressing sheath blight disease in the field. The purpose of this research was to determine the effectiveness of R. pickettii formulation in liquid and paste form. We formulated R. pickettii in liquid formulation by addition of glycerol to a final concentration of 25%. Paste formulation was made with composition of 44% talc, 3% xanthan gum, 3% molasses, 40% vegetable oil and 10% bacterial suspension. Efficacy test of both formulations was performed at concentrations of 5% and 10% in liquid formulation and 25 g/l and 50 g/l in paste formulation. Liquid formulation at both concentrations inhibited sheath blight disease at 5, 8, and 9 week after planting, whereas paste formulation with concentration of 50 g/l suppressed sheath blight disease at 5, 6, and 8 week after planting. However, paste formulation at concentration of 25 g/l only suppressed sheath blight disease at 8 WAP. Application of liquid and paste formulations did not affect plant height, number of tillers, and number of panicles of rice plants. Furthermore, application of liquid formulation at concentrations of 5% and 10% increased the fresh weight as much as 22% and 35%, respectively, and dry weight of grain as much as 26% and 32%, respectively. Otherwise, application of paste formulation at a concentration of 50 g/l increased the fresh weight of grain
Keyword: Rhizoctonia solani., paste formulation, liquid formulation, biological control agents, Ralstonia pickettii

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