Judul: Kemampuan aktinomiset endofit dalam meningkatkan pertumbuhan tanaman padi (Oryza sativa L.) melalui aktivitas asam Indol Asetat
Abstrak: Actinomycetes endophyte lives in plant tissue and may be able to produce various bioactive compounds. The bioactive compound produced by Actinomycetes endophyte can be useful to enhance the growth of plant through the activity of phytohormones substances produced, i.e. indole Acetic Acid (IAA). In vitro production of IAA from the ten isolates that were grown in ISP 2 liquid medium with the addition of 0.2 ml L-tryptophan 0.2% showed various concentration ranging about 11-99 ppm. Isolates producing high IAA were AB131-1 (99.2 ppm), AB131-2 (99,2 ppm), and PS4-16 (93.4 ppm). Those three superior isolates were then inoculated into rice seedlings which were then grown in pouches. Inoculation were designed in 20 different treatments, i.e. negative control, positive control (IAA 0.01, 0.1 dan 1 ppm), media control of ISP 2 liquid medium and supernatant of the three isolates in various concentrations. AB131-1 (1.05 ppm IAA) was considered as the most potential isolate based on its capability to increase plant height (26%), root length (33.4%) and dry weight (206%) more than the influence of IAA sintetic of 0.1 ppm addition. Microscopic observation of AB131-1 and PS4-16 of rice treatment using root coloring and Scanning Electron Micrographs (SEM) method showed that both of isolate were able to penetrate to the root of rice. The data showed that the application of Actinomycetes endophytic can increase the growth of rice plant.
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Judul: Kemampuan Aktinomiset Endofit sebagai Penambat Nitrogen dan Perannya dalam Meningkatkan Pertumbuhan Tanaman Padi, Pemanfaatan Filterisasi untuk Meningkatkan Daya Tampung Pesan pada Steganografi Pixel Value Differences (PVD)
Abstrak: Nitrogen is the nutrient that most frequently limits on paddy productivity. Excessive chemical nitrogen fertilizer applied on conventional farming may have negative impact to the degradation of environment. An alternative solution for this problem is by using biological nitrogen fixation (BNF) to enhance crop growth which can be done by applying nitrogen fixing endophytic actinomycetes. The objective of this research was to obtain endophytic actinomycetes isolates which have the capability in fixing N2 based on in-vitro and in-planta assay. Based on in-vitro assay, SSW-02 was considered as the most promising N2 fixing bacteria based on its ability to reduce 2.1750 nmol acetylene/hour and produced ammonia 2.144 ppm for 15 days in free nitrogen medium. In-planta assessment was conducted in a greenhouse using IR-64 rice variety on sterile and non sterile soil with two-factors completely randomized factorial design. The factors were endophytic actinomycetes treatments which consisted of SSW-02, AB131-2, control and urea dosage which consisted of 0%, 50%, 100% dosage from 200 Kg/Ha. Each treatment had been done in three replications. Based on in-planta assay, SSW-02 application with 100% urea dosage increased total plant dry weight and leaf color. Although not significantly different, SSW-02 application with 50% urea dosage also had the highest number of tillering and ability to increase plant height and root length. Nitrogen content also increased by SSW-02 application with 100% urea dosage in sterile soil. Microscopic observation of SSW-02 and AB131-2 of rice treatment using reducing tetrazolium method showed that both of isolates were able to penetrate and colonize the root of rice, confirming them as endophytes. The results indicated that SSW-02 had promising role as a N2 fixing bacteria on rice plant.
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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