Judul: The use of Bradyrhizobium japonicum and Aeromonas salmonicida for soybean growth in ultisol soil in greenhouse experiment
Abstrak: Soybean (Glycine max) was cultivated as food crops. The need of soybean always increase every year. The efforts to increase soybean production was used by application of biofertilizer and soybean cultivated in marginal land such as ultisol soil. Ultisol soil are common marginal land in Indonesia. Biofertilizer that used in this study consisted of Bradyrhizobium japonicum (BJ 11) as nitrogen fixation bacteria and Aeromonas salmonicida P3 (AS) as phosphate solubilizing bacteria. The aims of this research were to promote soybean growth in ultisol soil by using biofertilizer. The experiment was arranged with four treatments, those were inoculation with BJ 11, AS, BJ 11 and AS, and without inoculation (control). Isolates contained in the biofertilizer were expected to promote the growth of soybean (Glycine max) Tanggamus variety in ultisol soil by providing elements of nitrogen and phosphate. The results showed that B. japonicum and A. salmonicida as inoculant mixture tend to increase plant growth, leaf number, and root dry weight of soybean.
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Judul: Media Optimal untuk Bradyrhizobium japonicum Toleran Asam- Aluminium Memproduksi Asam Indol Asetat bagi Pertumbuhan Kedelai
Abstrak: The demand on soybean recently increase either in quantity or in quality. However, Indonesia have not been soybean self-supporting yet, since low production of soybean especially on acid land. Nitrogen and micro-elements are very low, and aluminium (Al) toxicity become problem in acid land, as well as Bradyrhizobium japonicum (Bj) could not survived. Some of B. japonicum strains are able to syntheses Indole Acetic Acid (IAA) with tryptophan precursor and soybean symbiosis. The objectives of this research were: (1) to find optimal media for IAA production by tolerance acid-Al B. japonicum on the various tryptophan concentrate, and (2) to see the distribution of B. japonicum inoculant and their effects on soybean cultivar Tanggamus growth. Bradyrhizobium japonicum and tryptophan concentrations used in this experiment were Bj 11(wt), Bj 11(19), KDR 15(wt), and USDA 110, and 0.75 mM; 1.00 mM; 1.25 mM; 1.50 mM. For second experiment combination of B. japonicum and tryptophan concentrations, Bj 11 (wt) 1.00 mM tryptophan, Bj 11 (19) 1.50 mM tryptophan, KDR 15 (wt), 1.50 mM tryptophan, USDA 110 1.25 mM tryptophan from first experiment, and without Bj but plus 1.00 mM tryptophan utilized on Tanggamus of soybean at growth–pouch pH 4.5 using randomized completely design, in six replication. Bradyrhizobium japonicum Bj 11(wt) 1.00 mM and Bj 11(19) 1.5 mM tryptophan gave primary root and lateral root length of soybean longer, number of lateral root, and IAA content of soybean increase better than standar strain USDA 110.
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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