Judul: Budidaya Buah Naga Putih (Hylocereus undatus) di Sabila Farm, Sleman, Yogyakarta dengan aspek khusus panen dan pascapanen
Abstrak: The internship activities was conducted in order to improve knowledge, field experience, and to analyze management aspect of dragon fruit cultivation and the harvest and postharvest handling. The internship activities was conducted at Sabila Farm, Sleman, Yogyakarta in February–June 2013. The resutls showed that dragon fruit cultivation in Sabila Farm could produce dragon fruit with great quality. Harvesting system at Sabila Farm was conducted based on the order of consumers and the purposes of agritourism. Dragon fruit harvesting by the labours was carried out manually based on the characteristics of harvesting. The labours in Sabila Farm have good skills for harvesting, therefore the loss of harvest due to the mechanical damage almost never occured. The yield losses that occured in Sabila Farm was caused by birds and chickens. Rainfall pattern affected the production of dragon fruit and the total of dragon fruit flowers based on correlation and regression analysis, especially rainfall pattern two months before for the flowering phase. The management of dragon fruit postharvesting in Sabila Farm overall was conducted properly, however in terms of grading and using bulkhead in packaging when selling it at the farm has not been implemented properly.
Keyword: Bogor Agricultural University (IPB), Sabila Farm, postharvest, harvest, dragon fruit, cultivation

Judul: Hama dan penyakit tanaman buah naga (Hylocereus sp.) serta budidayanya di Yogyakarta
Abstrak: Dragon fruit (Hylocereus sp.) has been introduced to Indonesia recently and became a commercial crop cultivated in this country. The plant, which belongs to family of Cactaceae (cactus), is native to Mexico, Central, and South America. There are no many reports about significant losses due to pests and diseases of the plant in Indonesia, or even in other countries. However, it is potential that pests and diseases can become problem in the future as the plant become widely grown in Indonesia. The objective of this research is to gather information about pest and disease occurrences found in dragon fruit and its cultivation in Yogyakarta. The research methods including interview with farmers, observation, and sampling of the pests and diseases at six dragon fruit orchards, field, and laboratory identification of the causal agents, and data processing. The pests found in dragon fruit were mealy bugs (Hemiptera:Pseudococcidae) species Pseudococcus jackbeardsleyi, Ferrisia virgata, and Planococcus sp.; aphids (Hemiptera:Aphididae) species Aphis gossypii., Branchycaudus helichrysi, and Toxoptera odinae; ants (Hymenoptera:Formicidae) species Oecophylla sp., Camponotus sp., Euprenolepis sp., and Polycharis sp.; grasshoppers (Orthoptera:Acrididae) species Valanga sp., Oxya sp., and Atractomorpha sp.; mite (Acarina:Tetranycidae); snail (Acathina fulica); and birds. Chickens are not considered as a pest, however, they can cause severe damage on fruit if they are allowed to present in the orchard. Diseases found in dragon fruit were algae red rust (Cephaleuros sp.), vine orange spot (Fusarium sp.), white vine (Botryosphaeria sp. and Phomopsis sp.), stem blight (Helminthosporium sp.) and anthracnose (Colletotrichum sp.), Dothiorella spot, brownish stem rot, stem yellowing, fruit rot (Colletotrichum sp. and Helminthosporium sp.) fruit orange spot (Alternaria sp.). A black spot disease on stem has not been identified yet. Pests and diseases have not been controlled in particular system, probably because their occurrences have not resulted in a significant loss.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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