Judul: Usaha Tani Tanaman Hias Sukulen di kabupaten Pekalongan Jawa Tengah dan Perlakuan Elektroterapi Bibit Kaktus Bergejala Sapu
Abstrak: Tanaman hias memiliki daya tarik tersendiri bagi masyarakat karena dapat membuat suasana tenang dan segar. Minat masyarakat tersebut membuat tanaman hias mempunyai nilai jual sehingga banyak dibudidayakan dan menjadi bisnis yang menguntungkan. Di Pekalongan, sukulen merupakan kelompok tanaman hias yang sering diminati oleh masyarakat karena bentuknya unik, cara perawatannya mudah serta kondisi iklim yang mendukung. Kaktus Opuntia sp. adalah contoh tanaman sukulen yang populer. Salah satu penyakit pada kaktus adalah sapu yang disebabkan oleh fitoplasma. Fitoplasma merupakan bakteri yang tidak memiliki dinding sel kaku yang tidak dapat dibiakkan, dan sulit dikendalikan. Perlakuan elektroterapi menggunakan arus listrik searah perlu diuji pada bibit kaktus untuk mengeliminasi fitoplasma. Tujuan dari penelitian ini adalah untuk mengetahui usaha budi daya tanaman hias sukulen di Pekalongan dan mengetahui pengaruh perlakuan elektroterapi fitoplasma pada bibit kaktus. Survei usaha tanaman hias dilakukan di Kabupaten Pekalongan dengan jumlah responden 20 orang. Usaha tanaman hias dilakukan di kios/lahan jual dengan luas 16-100 m2 . Pedagang belajar budi daya tanaman hias melalui petani lain, orang tua, bahkan internet. Pengalaman bertani mulai dari 2 hingga lebih dari 30 tahun. Pengendalian fitoplasma pada kaktus dengan perlakuan elektroterapi tidak berpengaruh nyata. Elektroterapi tidak dapat mengurangi gejala fitoplasma pada kaktus. Pertumbuhan tinggi tanaman kaktus sehat lebih cepat dibandingkan kaktus yang terkena fitoplasma, sedangkan lebar kaktus tidak mengalami perubahan. Kaktus yang sehat lebih lonjong dibandingkan kaktus yang terpapar fitoplasma., Ornamental plants have a special attraction for the community because they can create a lovely and fresh atmosphere. This community interest makes ornamental plants have a selling value so that they are widely cultivated and become a profitable business. In Pekalongan, succulents are a group of ornamental plants that are often in demand by the community because of their unique shape, easy maintenance and favorable climatic conditions. Opuntia sp. cacti are examples of popular succulent plants. One of the diseases on cacti is witches’ broom caused by phytoplasma. Phytoplasmas are bacteria that do not have rigid cell walls that cannot be cultured and are difficult to control. Electrotherapy treatment using direct electric current needs to be tested on cactus seeds to eliminate phytoplasma. The purpose of this study was to determine the cultivation of succulent ornamental plants in Pekalongan and to determine the effect of phytoplasma electrotherapy treatment on cactus seeds. Ornamental plant business survey was conducted in Pekalongan Regency with 20 respondents. Ornamental plant business is carried out in kiosks/selling areas with an area of 16-100 m2. Traders learn ornamental plant cultivation through other farmers, parents, and even the internet. Farming experience from 2 to more than 30 years. Control of phytoplasma in cactus with electrotherapy treatment had no significant effect. Electrotherapy cannot reduce the symptoms of phytoplasma in cacti. The height growth of healthy cactus plants was faster than the cactus affected by phytoplasma, while the width of the cactus did not change. Healthy cacti are more oval than those exposed to phytoplasma.
Keyword: Phytoplasma, Opuntia sp., farmer's perception, symptom remission

Judul: Electrotherapy of Cactus Cutting with Witches’  Broom Symptoms and Molecular Identification of Phytoplasma
Abstrak: Kaktus (Opuntia sp.) merupakan tanaman sukulen berduri yang digemari masyarakat di berbagai negara sebagai tanaman hias. Penyakit sapu pada kaktus diketahui disebabkan oleh fitoplasma. Saat ini, deteksi dan identifikasi fitoplasma mengandalkan teknik polymerase chain reaction (PCR) dan PCR amplicon nucleotide sequencing. Deteksi fitoplasma yang lebih sensitif seringkali perlu dilakukan dengan menggunakan teknik nested-PCR, PCR yang berurutan menggunakan dua pasangan primer yang berbeda tetapi pada daerah amplifikasi yang sama. Teknik elektroterapi menggunakan arus listrik belum banyak dilaporkan apakah dapat menekan patogen pada organ perbanyakan tanaman, baik benih maupun bibit, atau mempengaruhi pertumbuhannya. Perlakuan elektroterapi pada pertumbuhan kaktus seperti tinggi tanaman, lebar tanaman, dan jumlah tunas menunjukkan hasil yang positif. Pengaruh elektroterapi pada duri kaktus tidak menunjukkan pengaruh yang besar karena adanya duri dipengaruhi oleh gejala penyakit sapu itu sendiri. Rasio batang kaktus terhadap penyimpan cadangan air paling baik ada pada tanaman kaktus yang sehat dibandingkan dengan tanaman kaktus yang bergejala. Eliminasi fitoplasma dengan teknik elektroterapi pada tanaman kaktus bergejala memiliki batang dan pucuk yang lebih hijau dibandingkan dengan tanaman kaktus bergejala tanpa elektroterapi. Deteksi fitoplasma dari pemotongan kaktus yang sakit menggunakan PCR dengan primer P1/P7 hanya memberikan beberapa hasil yang positif. Reamplifikasi dengan nested-PCR dengan primer R16F2n/R16R2 meningkatkan jumlah sampel positif dengan pita DNA yang lebih baik. Fitoplasma dari kaktus asal Indonesia berkerabat dekat dengan fitoplasma-fitoplasma asal kaktus negara lain dan diidentifikasi sebagai fitoplasma grup 16SrII (Peanut witches' broom) berdasarkan analisis nukleotida gen 16S rRNA. Kata Kunci: 16S rRNA, arus listrik DC, pohon filogenetik, fitoplasma grup 16SrII, nested-PCR, Cactus (Opuntia sp.) is a thorny succulent plant that is favored by people in various countries as an ornamental plant. Cactus witches’ broom is known to be caused by phytoplasma. Currently, phytoplasma detection and identification rely on polymerase chain reaction (PCR) techniques and PCR amplicon nucleotide sequencing. Detection of more sensitive phytoplasmas often needs to be done by using the nested-PCR technique, successive PCR using two different primer pairs but from the same amplification region. Electrotherapy technique using electric currents has not been widely reported on whether they can suppress pathogens in plant propagation organs, both seeds, and seedlings, or affect their growth. Electrotherapy treatment on cactus growth such as plant height, plant width, and number of shoots showed positive results. The effect of electrotherapy on cactus thorns did not show a large effect because the presence of thorns was influenced by the symptoms of the broom disease itself. The ratio of cactus stems to the storage of water reserves is best for healthy cactus plants compared to symptomatic cactus plants. Elimination of phytoplasma by electrotherapy technique on symptomatic cactus plants had greener stems and shoots compared to symptomatic cactus plants without electrotherapy. Detection of phytoplasma from diseased cactus cutting using PCR with primers P1/P7 only yielded a few positive results. Reamplification by nested-PCR with R16F2n/R16R2 primers increased the number of positive samples with better DNA bands. Cactus phytoplasma from Indonesia are closely related to phytoplasmas from cactus from other countries and were identified as phytoplasma group 16SrII (Peanut witches' broom) based on nucleotide analysis of the 16S rRNA gene.
Keyword: 16S rRNA, arus listrik DC, Pohon filogenetik, fitoplasma grup 16SrII, nested-PCR

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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