Judul: Pengaruh asam humat dan cara pemberiannya terhadap pertumbuhan dan produktivitas tanaman padi (Oryza sativa)
Abstrak: Agricultural land in Indonesia degraded continuously, characterized by decreasing in soil organic matter resulting from the utilization of chemical fertilizers which is not followed by organic fertilizers. In the rice field, the decrease of organic matter is followed by soil compacting and the decrease in soil pH. In order to increase paddy production, it is needed to improve the soil qualities plants growth. This can be achieved by providing ameliorants such as organic matter with chemical fertilizers. But there is a problem in applying organic matter because of its huge volume. Therefore, it is necessary to find a way to replace the organic matter with other materials that are easier not only in procurement but also in application. Humic acid is an extract of organic material which is expected to be able to replace the role of organic matter in improving physical, chemical, and biological properties of soils. Humic acid is expected to be able for improve plant growth through its role in accelerating the absorption of soil nutrients and water. The research was conducted in a greenhouse located at Cikabayan, Bogor Agricultural University with paddy var. Ciherang as the indicator plant. Soil was taken from Situ Gede, Bogor. Basal fertilizers were 300 kg/Ha SP-18, 200 kg/Ha KCl, and 200 kg/Ha urea. Humic acid dosages used were 0 L/Ha, 5 L/Ha, 10 L/Ha and 15 L/Ha. The methods of humic acid application were spraying on the surface of leaves, spraying underside of leaves, and spraying on the soil. The result showed that humic acid can increase the growth of rice plants by increasing tiller number. Humic acid dosage of 15 L/Ha spraying on the soil is the best treatment indicated by tiller number and dry weight of unhulled rice.
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Judul: Pengaruh Cara Pemberian dan Dosis Bahan Humat Terhadap Produksi Tanaman Padi (Oryza sativa L) di Desa Sidosari, Kecamatan Natar, Lampung Selatan
Abstrak: Demand of rice in Indonesian will continuously increase following the population growth. Increasing demand of rice must be balanced by improvement of rice productivity. One of efforts that can be done to increase rice productivity is by improving soil properties either physically, chemically and biologically. Addition of organic matter may improve soil properties, but organic matter such as compost and manure is needed in large amounts. Humic substance is known able to replace a part of organic matter role. Treatment of humic substance on soil and plant is expected to be able to improve productivity of rice. The aim of this research was study effect of humic substance on growth and productivity of rice by different method and dosage application. The research was conducted at Sidosari village, Natar District, South Lampung Regency using Ciherang rice variety. Fertilizers used were 350 kg/ha Phonska, 200 kg/ha Urea, and 100 kg/ha SP-18. The treatments were composed of treatment of without humic substance, humic substance addition to soil, and humic substance addition to soil and leaves. Addition of humic substance to soil conducted on land preparation, while addition of humic substance to the leaves was done when the plants were 2 to 8 week after transplanting with an interval of two weeks. Humic substance dosages were 15 l/ha that diluted to 4 ml/l for soil and 2 ml/l for leaves. The results showed that the growth and yield components increased in plants treated with humic substance. The weight of grain yield of the plant without humic substance equivalent to 6.7 ton/ha, whereas that of plant with humic substance addition to soil was 7.14 ton/ha, and that of plant with humic substance addition to soil and leaves was 7.86 ton/ha.
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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