Judul: Pencegahan Rebah dan Busuk Kecambah (Colletotrichum gloeosporioides (Penz.) Sacc.) Pada Pepaya Calina Oleh Beberapa Agens Biokontrol
Abstrak: Calina (IPB-9) is one of the superior varieties of papaya that have been released by IPB. This variety is susceptible to the causal agent of anthracnose. Anthracnose caused by Colletotrichum gloeosporioides is an impotant disease of papaya that reduce the quality of papaya in the storage. However, this patogen also caused damping-off and seedling rot at nursery. Therefore, this study purposed to evaluate the effectiveness of five biocontrol agents (Trichoderma harzianum (TH17), Gliocladium fimbriatum (G84), Bacillus subtilis (B12) and Actinomycetes (APS5 and APS12)) to reduce damping-off or seedling rot caused by Colletotrichum gloeosporioides on Calina (IPB-9). This study using in vitro test by dual culture and baiting poisonous methods and in vivo test by pouring their suspension into polybag. The result of in vitro experiments showed that TH17 and G84 were most effective to suppressing the growth of C. gloeosporioides with resistance level reached 100% on α = 5%. In the in vivo experiments, using the suspension of B12 and G84 were most effective suppressing incidental disease of damping off with relative resistance level 66.67% on α = 5%.
Keyword: Seedling disease, biocontrol agent, antraknosa, seedbed papaya calina

Judul: Utilization of Yeasts Antagonists to Extend Shelf Life and Control Anthracnose Disease of Papaya Fruit
Abstrak: Pepaya adalah buah klimakterik yang memiliki umur simpan pendek dan penyakit antraknosa yang disebabkan oleh Colletotrichum gloeosporioides. Penanganan pascapanen yang kurang baik dapat menyebabkan kerusakan buah yang berakibat pada penurunan kualitas buah. Kehilangan pascapanen terbesar disebabkan oleh penyakit antraknosa dan karena buah lewat matang. Pemanfaatan khamir antagonis sebagai agens pengendali hayati merupakan salah satu alternatif pengendalian penyakit pascapanen dan untuk menunda proses kematangan buah pepaya. Pencegahan penyakit antraknosa pada buah pepaya umumnya dilakukan dengan menggunakan fungisida. Namun pengendalian dengan fungisida sintetik kurang efektif dan menimbulkan berbagai masalah lingkungan serta residu pada produk pascapanen. Oleh karena itu perlu dilakukan penelitian mengenai agens hayati yang sesuai untuk memperpanjang umur simpan dan mengendalikan penyakit antraknosa pada buah pepaya Callina. Tujuan dari penelitian ini adalah mengkaji keefektifan beberapa spesies khamir antagonis untuk memperpanjang umur simpan dan mengendalikan penyakit antraknosa pada buah pepaya Callina. Penelitian ini menggunakan rancangan kelompok lengkap teracak (RKLT) dengan perlakuan lima jenis khamir yaitu Cryptococcus albidus Yp, Aureobasidium pullulans Dmg 30 DEP, Rhodotorula minuta Dmg 16 BEP, Candida tropicalis Lm 13 BE, dan Pseudozyma hubeiensis Dmg 18 BEP, dan sebagai pembanding perlakuan fungisida berbahan aktif azoksistrobin serta tanpa perlakuan sebagai kontrol. Penggunaan khamir Candida tropicalis, Aureobasidium pullulans, dan Cryptococcus albidus dapat memperpanjang umur simpan buah pepaya Callina masing-masing 12,6, 12,4, dan 12,2 hari, lebih lama dibandingkan kontrol yang hanya 7 hari dan efektif mengendalikan penyakit antraknosa dengan tingkat penekanan secara berturut-turut 58,33%, 54,17%, dan 50,00%, selama penyimpanan. Karakter fisiologi atau biokimia buah lain nya seperti susut bobot, kekerasan kulit buah, kekerasan daging buah, padatan terlarut total (PTT), asam tertitrasi total (ATT), rasio PTT/ATT, dan vitamin C tidak dipengaruhi oleh perlakuan khamir. Buah pepaya Callina dengan perlakuan khamir Candida tropicalis dan Aureobasidium pullulans lebih disukai panelis karena memiliki rasa manis yang lebih dominan. Hasil uji in vitro menunjukkan bahwa perlakuan khamir Candida tropicalis, Aureobasidium pullulans, dan Cryptococcus albidus paling efektif untuk menekan pertumbuhan Colletotrichum gloeosporioides dengan persentase penghambatan secara berturut-turut 37,67%, 31,33%, dan 28,33% pada 7 hari setelah inokulasi (HSI). Seluruh khamir antagonis memiliki mekanisme pengendalian antraknosa buah pepaya melalui pembentukan senyawa volatil., Papaya is one of the climacteric fruit that has a short shelf life and anthracnose disease caused by Colletotrichum gloeosporioides. Poor postharvest handling can cause fruit damage which results in a decrease in fruit quality. The largest postharvest losses were caused by anthracnose disease and due to late ripening. Utilization of yeasts antagonists as biological control agents is an alternative for postharvest disease control and to delay the ripening process of papaya fruit. Prevention of anthracnose on papaya fruit is generally performed by using fungicide. However, control with synthetic fungicides is less effective and causes various environmental problems and residues in postharvest products. Therefore it is necessary to conduct research on suitable biological agents to extend shelf life and control anthracnose diseases in Callina papaya fruit. The purpose of this study was to investigate the effectiveness of several antagonistic yeast species to extend shelf life and control anthracnose disease on the Callina papaya fruit. The experiment was arranged in a randomized complete block design with the treatment of five types of
Keyword: climacteric fruit, Colletotrichum gloeosporioides, postharvest

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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