Judul: Morphophysiological Characters, Quality, and Physicochemical of Rice from Five Varieties of Rice using Microbial-enriched Organic Fertilizer
Abstrak: The excessive use of chemical fertilizers and pesticides in rice cultivation has an impact on the degradation of agricultural land. The role of microbial enriched organic fertilizer as a source of soil organic matter is an option in overcoming land degradation and decreasing crop productivity. Microbes such as Azospirillium, Azotobacter, Bacillus, and Pseudomonas can increase the availability of soil nutrients so that plants quickly absorb them. This study aims to determine the morphology, physiological character, quality, and physicochemical of five rice varieties with various doses of microbial-enriched organic fertilizer, and to determine the optimum dose of microbial-enriched organic fertilizer for each rice genotype. This research was carried out from July 2020 to January 2021 at the Sawah Baru Experimental Site, Faculty of Agriculture, IPB University, and from March 2021 to September 2021 at the Laboratory of Applied Sciences, Faculty of Agricultural Technology, IPB University. The experiment was carried out using a Split-plot Design with 3 replications. The main plots were doses of organic fertilizer enriched with microbes consisted of 0, 10, 20, and 30 tons ha-1 , and the sub-plots, namely rice varieties including IPB 3S (a new type of rice), Inpari 24 (brown rice inbred), Hipa 18 (hybrid), Inpari 32 (new high yielding variety), and Tarabas (japonica). The data were analyzed using Analysis of variance (ANOVA) followed with the Duncan Multiple Range Test (DMRT). The results showed that the application of microbial-enriched organic fertilizer significantly increased plant height, number of tillers, root dry weight, shoot dry weight, leaf greenness, number of grain per panicle, and productive tillers. Applying 30 tons ha-1 of organic fertilizer can increase dry grain weight per plant by 25.78%. The yield of grain produced after applying 10 to 30 tons ha-1 of organic fertilizer increased by 12.91% to 32.5%. The application of organic fertilizer up to 30 tons ha-1 still increase grain productivity per hectare therefore the optimum dose for microbial-enriched organic fertilizer cannot be determined yet. Physicochemical analysis showed that the application of microbial-enriched organic fertilizer resulted in rice yields ranging from 64.6 to 64.9%. Inpari 24 (brown rice inbred) and Tarabas (japonica rice) had the lowest amylose content. The results of the cooking properties analysis showed that Inpari 24 had moderate gel consistency. Consumer preferences from organoleptic test results liked the color, aroma, taste, and texture of rice at all doses of microbial enriched organic fertilizer and the five rice varieties.
Keyword: gel consistency, hybrid, microbes, nutrient uptake, viscosity

Judul: Increased Rice Yield (Oryza sativa L.) with Application of Organic Fertilizer Enriched with Microbes
Abstrak: Produktivitas padi Indonesia beberapa tahun terakhir mengalami penurunan. Pemupukan yang sesuai dengan kondisi tanah dan kebutuhan tanaman mampu meningkatkan produksi tanaman. Aplikasi pupuk organik diperkaya dapat meningkatkan kesuburan tanah. Mikroba yang hidup di perakaran tanaman atau PGPR dalam pupuk dapat meningkatkan ketersediaan hara dalam tanah dan mensintesis hormon pertumbuhan tanaman melalui aktivitas biologisnya. Penelitian ini bertujuan untuk mempelajari pengaruh aplikasi pupuk organik diperkaya terhadap peningkatan hasil padi sawah dan pengurangan dosis pupuk anorganik. Rancangan yang digunakan adalah rancangan kelompok lengkap teracak satu faktor yaitu dosis pupuk dengan 4 ulangan. Penelitian dilaksanakan di Kebun Pendidikan Sawah Baru IPB. Analisis tanah dan analisis kandungan pupuk dilaksanakan di Laboratorium Kimia dan Kesuburan Tanah, Departemen Ilmu Tanah dan Sumber Daya Lahan, Laboratorium Pengujian Departemen Agronomi dan Hortikultura, serta Laboratorium Tanah, Tanaman, Pupuk, Air, Balai Penelitian dan Pengembangan Pertanian. Pelaksanaan penelitian dimulai pada November 2020 hingga April 2021. Pengamatan dilakukan terhadap pertumbuhan, hasil, dan komponen hasil padi sawah. Hasil penelitian ini menunjukkan aplikasi pupuk organik diperkaya secara umum tidak meningkatkan pertumbuhan dan hasil per tanaman maupun hasil per hektar padi sawah. Aplikasi pupuk organik diperkaya dapat mengurangi 25% penggunaan pupuk anorganik dengan nilai efektivitas agronomi relatif sebesar 108,8%., Rice productivity in Indonesia has decreased in recent years. Fertilization that is suitable for soil conditions and plant needs can increase crop yield. The application of bioorganic fertilizer would be able to increase soil fertility. Microbes that live in plant roots could increase the availability of nutrients in the soil and synthesize plant growth hormones through their biological activities. The research aims to study the effect of the application of organic fertilizer enriched with microbes on increasing growth, yield, and yield components of lowland rice and the reduction of the dose of inorganic fertilizer. The experimental design used was a randomized complete group design with one factor, namely the dose of fertilizer with 4 replications. The research was carried out at the Sawah Baru Teaching Farm, IPB. Soil analysis and analysis of fertilizer content were carried out at the Laboratory of Chemistry and Soil Fertility, Department of Soil Science and Land Resources, Testing Laboratory of the Department of Agronomy and Horticulture, and the Laboratory of Soil, Plants, Fertilizer, Water, Agricultural Research and Development Center. The experiment was conducted from November 2020 until April 2021. The observations made were observations of vegetative and generative characters, as well as yields. Results shows, the application of enriched organic fertilizers did not increase growth and yield per plant or yield per hectare of lowland rice. Application of enriched organic fertilizers, however, could reduce 25% of inorganic fertilizers usage with a relative agronomic effectiveness value of 108.8%.
Keyword: effectiveness, organic fertilizer, PGPR, rice, yield

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