Judul: Pengaruh pengolahan tanah, pemberian bahan organik dan penggunaan mulsa terhadap permeabilitas tanah, ketersediaan basa-basa dalam tanah (k, Ca, Mg, dan Na) dan produksi jagung manis (Zea mays Saccharata) Var SD 2, pada anah latosol (Humitropept Oxic) Jampang Tengah-Sukabumi
Abstrak: Sejalan dengan pertambahan penduduk terjadilah peningkatan kebutuhan hidup, baik secara kuantitas maupun kualitas. Pada pihak lain ketersediaan sumberdaya lahan tetap dan sangat terbatas. Keadaan dua hal yang saling bertentangan tersebut akan meningkatkan tekanan penduduk atas sumberdaya lahan, yang akhirnya terjadilah kerusakan lahan. Produktivitas tanah dapat ditingkatkan melalui penerapan teknologi pengelolaan tanah yang tepat yaitu yang memperhatikan kaidah-kaidah dari konservasi tanah dan air. Pengolahan tanah yang baik, pemberian bahan organik dan penggunaan mulsa merupakan suatu paket teknologi tepat guna yang diharapkan dapat meningkatkan dan mempertahankan produktivitas tanah yang lestari. Tujuan dari penelitian ini untuk mengkaji pengaruh teknik pengolahan tanah, pemberian bahan organik dan penggunaan mulsa terhadap permeabilitas tanah, ketersediaan basa-basa dalam tanah, serta produksi jagung manis. ...
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Judul: Pengaruh pengolahan tanah dan pemberian bahan organik terhadap beberapa sifat fisik tanah dan produksi jagung manis (Zea mays saccharata) pada latosol Jampang Tengah Sukabumi
Abstrak: Penelitian ini dilakukan di lahan milik Kelompok Tani Sadagori di Kampung Nangela, Kecamatan Jampang Tengah, Kabupaten Sukabumi. Penelitian ini bertujuan untuk mengetahui pengaruh pengolahan tanah dan pemberian bahan organik terhadap beberapa sifat fisik tanah dan produksi jagung manis. Penelitian ini dilakukan dengan memberikan perlakuan yang terdiri dari 4 jenis pengolahan tanah dan 3 taraf pemberian bahan organik. Keempat jenis pengolahan tanah tersebut yaitu 1) tanpa pengolahan tanah (PO); 2) pengolahan minimum (P1) yaitu pengolahan tanah selebar 20 cm di kanan-kiri baris tanaman sedalam 20 cm dengan pencangkulan; 3) pengolahan tanah 20 cm yaitu pengolahan tanah dengan pencangkulan sampai kedalaman 20 cm pada seluruh permukaan tanah; dan 4) pengolahan tanah intensif (P3) yaitu pengolahan tanah sedalam 20 cm lalu digemburkan dengan mencangkul beberapa kali. Ketiga taraf pemberian bahan organik adalah: 1) 0 ton/ha (K1), 2) 15 ton/ha (K2), dan 3) 30 ton/ha (K3). Pemberian bahan organik berupa kotoran domba yang telah matang (kering) dilakukan dengan ..dst
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Judul: Identifikasi Molekuler Kompleks Spesies Himantura uarnak (Batoidea: Dasyatidae) di Indonesia.
Abstrak: Stingrays are one of the cartilaginous fish, apart of sharks and skates, and one of Indonesia's fishery resources. Almost of elasmobranch fishes are economically important fish. The refined products and live specimens of this fish are a lot of traded. Himantura uarnak, H. undulata and H. leoparda are stingray species in Himantura and Dasyatidae family, which are the most popular stingrays in Indonesia waters. The stingrays are major target species were used as a consumable product and trading products. Levels of species diversity of cartilaginous fish in Indonesia are very high, and also Indonesia is listed as one of the countries that use elasmobranch resources the highest in the world. Generally, this study aims to identify each species of H. uarnak species complex through molecular approaches. While specifically, this study aims to estimate the evolutionary process of species divergence and to determine the relationship between species. The methods were used in this study included field sampling, sample collection, and specimen identification, collection of genetic samples, analysis of genetic samples and data analysis . Size polymorphism nuclear DNA markers (intron EPIC) were used. Polymorphism alleles translated into genotypes and alleles frequency of five introns loci. The results of Bayesian analysis and Correspondence Analysis (CA) produced informative diagram of the population structure showed 4 different clusters. Cluster 1 and 4 were H. leoparda, Cluster 2 indicated as H. undulata and the Cluster 3 was H. uarnak. Cluster 1 was a variant of Cluster 4, in this time called as H. leoparda var.1. Separation of four clusters according to nuclear DNA need to be proved by mitochondria DNA maker by cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b). Molecular approaches were using mitochondrial DNA gene cytochrome c oxidase subunit I (COI) and cytochrome b produced 4 main groups (Group I, II, III and IV). Both of these molecular approaches showed each individual of groups were in consistent clade and the main group. Hence the H. uarnak species complex in Indonesian waters were divided into 4 main groups, and each was a particular species. The Group I and IV were the two group species that have been released as H. leoparda and Group I was H. leoparda var. 1 identified as cryptic species. Group II was one individual who grouped as H. undulata. Group III was one of other group that identified as H. uarnak and in accordance with the morphological characteristic through spotting pettern. Morphological approach to identified the stingrays of Himantura uarnak species complex clearly less accurate than the molecular approaches. Morphological approach should not be used to identify a species complex in stingrays without helped by other approaches.
Keyword: Himantura uarnak species complex, intron EPIC, cyt b, COI, spotting pattern