Judul: Pengaruh pemupukan fosfor dan kalsium terhadap serapan hara dan produktivitas dua genotipe kedelai pada budidaya kering dan jenuh air
Abstrak: The objectives of this research were to study the effect rates of P and Ca fertilizers on productivity and nutrient uptake of two soybean genotypes in dry culture and saturated soil culture, and to compare the nutrient uptake and productivity in soybean dry culture with saturated soil culture. The experimental design was split split plot with three factors i.e. phosphorus, calcium and genotype planted in dry culture and saturated soil culture. Dry culture with phosphorus fertilizer application (72 kg P2O5/ha) increases the number of filled pods and grain weight per plot. Number of pods of Tanggamus variety was greater than Anjasmoro variety. Liming had no effect on productivity. Path analysis showed that largest direct effect to grain weight were plant height and leaf weight. Increased rate of P and Ca fertilizer increased the uptake of P and Ca, but variety Tanggamus is more responsive than variety Anjasmoro. Saturated soil culture with phosphorus fertilizer (72 kg P2O5/ha) and lime (1 ton/ha) increased the number of pods content and grain weight per plot. Variety Tanggamus had higher number of pods and grain weight per plot than variety Anjasmoro. Interaction of phosphorus fertilizer 72 kg P2O5/ha with lime 1 ton/ha increased grain weight per plot. Largest direct effect on increasing grain weight is plant height and the number of branches. Phosphorus application (72 kg P2O5/ha) and liming (1 ton/ha) also give highest uptake of P and Ca. Saturated soil culture technology can be applied to increase soybean nutrient uptake and productivity than dry culture.
Keyword: 

Judul: Growth and Productivity of Soybean with Phosphate Fertilization Dose and Frequency on Saturated Soil Culture in Tidal Swamp
Abstrak: Konsumsi kedelai di Indonesia tahun 2020 mencapai 2,87 juta ton, sedangkan produksi nasional hanya 613.300 ton karena luas lahan kedelai menurun akibat persaingan komoditas dan perubahan lahan pertanian. Lahan pasang surut menjadi alternatif peningkatan areal pertanian menggunakan teknik budidaya jenuh air. Penelitian bertujuan mempelajari dosis dan frekuensi pemupukan P terhadap pertumbuhan dan produktivitas kedelai dengan budidaya jenuh air di lahan pasang surut. Penelitian menggunakan rancangan kelompok lengkap teracak faktorial dengan dua faktor dan tiga ulangan. Faktor pertama adalah dosis pupuk P terdiri atas: 36, 72, dan 108 kg P2O5 ha-1 (180, 360, dan 540 kg Fertiphos ha-1). Faktor kedua adalah frekuensi pemupukan P terdiri atas; pada saat tanam 0 hari setelah tanam (HST), 0 dan 30 HST, dan 0, 30, 60 HST. Perlakuan berbagai dosis pemupukan fosfat berpengaruh nyata terhadap peningkatan tinggi tanaman, jumlah cabang, jumlah daun, luas daun, bobot basah batang, bobot kering batang, bobot kering daun, jumlah polong isi, jumlah polong hampa, bobot biji ubinan, dan produktivitas. Perlakuan berbagai frekuensi pemupukan fosfat berpengaruh nyata terhadap peningkatan tinggi tanaman, jumlah cabang, jumlah bintil akar, jumlah polong isi, dan jumlah polong hampa. Dosis pupuk 108 kg P2O5 dan frekuensi pemupukan fosfat dengan tiga kali pemupkan pada 0, 30, dan 60 HST menjadi kombinasi terbaik untuk peningkatan produksi kedelai. Dosis pupuk 108 kg P2O5 ha-1 menghasilkan produksi kedelai tertinggi sebesar 2,60 ton ha-1., Indonesia's soybean consumption is estimated to reach 2.87 million tons in 2020. Meanwhile, the national production is only 613,300 tons as the soybean area is decreasing due to commodity competition and agricultural land changes. Tidal land is an alternative to increase agricultural area using water-saturated cultivation techniques. The research aimed to study the dose and frequency of P fertilization on the growth and productivity of soybean plants with water-saturated cultivation on tidal land. The study used a factorial randomized complete block design with two factors and three replications. The first factor was the dose of P fertilizer consisting of: 36, 72, and 108 kg P2O5 ha-1 (180, 360, and 540 kg Fertiphos ha-1). The second factor is the frequency of P fertilization consisting of; at planting 0 days after planting (DAP), 0 and 30 DAP, and 0, 30, and 60 DAP. The treatment of various doses of phosphate fertilization had a significant effect on increasing plant height, branch number, leaf number, leaf area, stem fresh weight, stem dry weight, leaf dry weight, number of filled pod number, number of empty pods, seed weight, and productivity. The treatment of various phosphate fertilization frequencies significantly increased plant height, number of branches, number of root nodules, number of filled pods, and number of empty pods. The fertilizer dose of 108 kg P2O5 ha-1 and phosphate fertilization frequency at 0, 30, and 60 DAP the best combination for increasing soybean production. The fertilizer dose of 108 kg P2O5 ha-1 resulted in the highest soybean seed yield as much as 2.60 tons ha-1.
Keyword: Fosfor, Lahan rawa, Varietas Demas 1, Phosphorus, swamplands

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