Judul: Potency of Moringa (Moringa oleifera Lam.) and Bougainvillea (Bougainvillea spectabilis Willd.) Leaf Extract in Suppressing Mottle Virus Infection on Peanuts
Abstrak: Penyakit belang merupakan penyakit penting pada tanaman kacang tanah dan menyebabkan kerugian secara ekonomi. Virus belang ditularkan secara mekanis, melalui vektor kutudaun dan terbawa benih, sehingga perlu berbagai upaya pengelolaan karena termasuk virus yang sulit dikendalikan. Salah satu upaya pengelolaan virus belang adalah dengan pemanfaatan ekstrak tanaman. Penelitian ini bertujuan menguji efektivitas ekstrak daun kelor dan ekstrak daun bugenvil dalam menekan infeksi virus belang pada kacang tanah. Pengujian terdiri atas 4 perlakuan yaitu kontrol sehat, kontrol terinfeksi virus tanpa perlakuan ekstrak, ekstrak daun kelor dan ekstrak daun bugenvil yang diinokulasi virus. Peubah yang diamati adalah parameter penyakit dan parameter agronomi. Percobaan dirancang dengan rancangan acak lengkap, setiap perlakuan terdiri atas 10 tanaman sebagai ulangan. Hasil penelitian menunjukkan bahwa pemberian ekstrak daun bugenvil dan ekstrak daun kelor menghambat insidensi penyakit, secara nyata memperpanjang periode inkubasi dan menekan keparahan penyakit, serta titer virus belang dibandingkan kontrol tanpa perlakuan. Daya kecambah, indeks vigor, dan tinggi tanaman yang diberi perlakuan ekstrak tanaman tidak berbeda nyata dengan kontrol tanpa perlakuan. Namun, jumlah daun tanaman nyata lebih banyak dan vigor visual pertumbuhannya lebih baik dibandingkan kontrol. Hal ini menunjukkan potensi kedua ekstrak daun tanaman memiliki aktivitas antivirus dan potensi dalam meningkatkan pertumbuhan tanaman., Mottle disease is significant disease of peanut plants and causes economic losses. The mottle virus is transmitted mechanically by aphid vectors and by seeds. It needs various management efforts because the virus is difficult to control. One of efforts to manage mottle virus is by utilizing plant extracts. This study aimed to test the potency of moringa and bougainvillea leaf extracts to suppress mottle virus infection on peanuts. The test consisted of four treatments: healthy control, untreated control infected by virus, moringa and bougainvillea leaf extracts treatment prior virus infection. The disease and agronomic parameters were measured. The experiment was designed with a completely randomized design. Each treatment consistied of 10 plants as repetition. The results showed that the application of moringa and bougainvillea leaf extracts showed lower disease incidence, able to prolong the incubation period, and decreased disease severity as well as virus titer significantly in compared to untreated control. The germination capacity, vigour index, and plant’s height of among treated plants and untreated control were not significantly different. However, the leaf numbers significantly higher and the plants visual vigour were better than the control. These indicating that both plant leaf extracts posses an antiviral activity and potential ability to improve plant’s growth.
Keyword: Antiviral, Mottle virus, Plant extract, Antivirus, Ekstrak tanaman, Virus belang

Judul: Efikasi Beberapa Ekstrak Tanaman untuk Mengendalikan Bean common mosaic virus pada Kacang Panjang di Lapangan
Abstrak: Yard long bean is an important vegetable in Indonesia. One of its production constraint is the infection of Bean common mosaic virus (BCMV). In the field, BCMV infection is difficult to be controlled. One of effort to control the virus is by utilizing antivirus substances from plant origin. The conducted research aim was to test the effectiveness of plant extracts considerably containing antivirus substances to control BCMV on yard long bean in the field trial. Fourteen plants species were applied as crude and protein extracts which were sprayed on the leaves an hour before mechanical inoculation of BCMV. The experiment was arranged by using randomized block design. Each treatment consist of 3 blocks as replicate. Incubation period, disease incidence, symptom, disease severity and titer of BCMV were measured. The result showed that either crude extract or protein extract prolonged the incubation period and decreased the disease severity. Relative inhibition level of severity and BCMV titer of crude extract treatments ranged from 48,4% to 89.8% and from 59.8% to 99.1%, whereas protein extract treatment ranged from 43.2% to 74.4% and from -55.1% to 42.7%, respectively. Crude extract treatment showed more effective to control BCMV infection than protein extract treatment. Among tested plant extracts, Bougainvillea spectabilis and Psidium guajava crude extracts showed highest relative inhibition level of severity and BCMV titer in controlling BCMV in the field.
Keyword: yard long bean, plant extract, BCMV, antivirus

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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