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: Teknologi formulasi pupuk hayati rizobakteria dan aplikasinya sebagai pemacu pertumbuhan tanaman kedelai dan biofungisida pada tanah masam
Abstrak: Soybean production in Indonesia is still low, therefore Indonesian government must import soybean from other countries up to 45-50% to fulfill national requirement. This is a problem that should be solved through many approaches. One of the approach to increase soybean production through the use of plant growth promoting rhizobacteria (PGPR) that have been understood important in plant health and fitness. Our previous study resulted several indigenous strains of Pseudomonas sp. and Bacillus sp. from soybean rhizosphere that are combined with nitrogen-fixing bacteria Bradyrhizobium japonicum from soybean plant. The combinations of these bacteria were potential as plant growth promoter and biocontrol for root phytopathogenic fungi (biofungicide). For further use of these rhizobacteria, need to be developed bioprocess technology for formulation of inoculants production to increase soybean productivity. Objective of this research was to made biofertilizer containing rhizobacteria to be applied on soybean in acid soils. This research was conducted in 3 stages; optimalization media production in laboratory, formulation and bioassay in the greenhouse. The best medium for inoculants production are skim milk and molasses that produce bacterial population of 108-109 cfu/ml. Peat and talcum powder were used to formulation as carrier material. Three kind of prototype were produced; there were M-Sr (isolate Cr24, Crb17 dan Bj11); M-Rs (isolate Cr55, Crb64 dan Bj11); dan M-Fo (isolate Cr76, Crb86 dan Bj11). Each inoculant formed to three forms of formulations; there were granules (G), talc powder (T) and peat powder (S). Greenhouse test showed that several combinations of bacteria in the formula can stimulate the height of soybean plant, root weight, and plant performance. The biofertilizer applied with doses 400 g/ha for talc powder and peat powder. Rhizobakteria inoculants can be used as biofungicide. Disease suppression on Sclerotium roflsii, Rhizoctonia solani and Fusarium oxysporum respectively 79.98%, 27.27%, 50.12%. Storage up to 6 months was still able to maintain the bacterial population to 107-108 cells/g. Based on this result, we will asses this formula in field experiments under acid soils.
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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. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular