Judul: The In Vitro Tetraploid Induction of Tangerine (Citrus nobilis Lour.) Using Colchicines.
Abstrak: Seedless fruit is one of the criteria necessary to improve the quality of Simadu tangerine. The most effective method to obtain seedless triploid cultivars is hybridisation between tetraploid and diploid parents. The aim of this research was to obtain tetraploid Simadu tangerine planlet which would serve as parent to produced seedless Simadu tangerine. The experiment was conducted at Biology Cell and Tissue Laboratory of BB-Biogen and Micro Technique Laboratory of Agronomy and Horticulture Department, IPB, Bogor from January to August 2013. In vitro Simadu tangerine shoot-tips without leaves, lateral shoots without leaves and somatic embryos globular phase were treated with colchicines at four different concentrations (0%, 0.1%, 0.2%, and 0.3) for 3 hours (Shoot-tips), 6 hours (lateral shoots) and 1 hour (globular). The result of in vitro tetraploid induction of tangerine shoot-tip showed that colchicine treatments reduced growth of shoot-tip of Simadu Tangerine. The leaves of colchicines treated shoots were thicker than control. Leaves from control (0% colchicine) and 0.1% colchicine treated shoots had 8.67 and 18.25 chloroplasts per pair of guard cells. Leaves from 0.1% colchicine treated shoots had stomata sizes were larger than control shoots. Leaves from 0.1% colchicine treated shoots had stomata density was lower than control shoots. The tetraploid Simadu tangerine shoots were produced by the treatment of 0.1% colchicine. The result of in vitro tetraploid induction of tangerine shoot-tip showed that the shoots of colchicines treated were taller than control. The shoots of colchicines treated had leaves were wider than control. The colchicines treatments increased numbers of chloroplasts per stomata guard cell. Leaves from colchicine treated shoots had stomata sizes were larger than control shoots. Leaves from colchicine treated shoots had stomata density was lower than control shoots. The result of in vitro tetraploid induction of tangerine somatic embryos showed that colchicine treatments with high concentration increased abnormal planlet percentage. The tetraploid Simadu tangerine planlets were produced using 0.2% colchicine and 0.3% colchicine.
Keyword: chloroplasts, doubling chromosome, mutation, stomata

Judul: Induction of genetic variability through gamma rays irradiation on embryogenic callus derived protoplast of tangerine cv. siam
Abstrak: Tangerine cv. Siam has sweet flavor, easily peeled skin, soft and juicy flesh. However, it has relatively many seeds (15-20 seeds per fruit), so it can not be competed with citrus from other countries. Fruit quality improvement of citrus has been the subject of citrus breeding program. The first step of breeding program is to increase variability, in order to efficient the selection process. Callus derived protoplast which sub cultured several years has a level of variability. The objective of this research was to increase variation of Tangerine cv. Siam through gamma irradiation on callus derived protoplast. Callus was exposed to gamma irradiation at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 Gray. Observation on the growth of callus four weeks after irradiation showed variation on morphology and weight of callus. At low doses (10-50 Gray) callus growth were not inhibited, but at high doses (60-100 Gray) callus growth were inhibited. The result of radio sensitivity dose analyzed by Curve Expert 1.4 software was 53.25 Gray. Callus regeneration ability (somatic embryo maturation and germination) were very diverse between irradiated and non-irradiated callus. Gamma irradiation affects the formation of somatic embryos. After four weeks on MW (Morel-Wetmore) medium containing 0.5 mg/l ABA, 50 Gray callus produced more somatic embryos than other doses. After four weeks on MW medium containing 0.5 mg/l GA3, only 75.9% somatic embryos from 50 Gray callus could germinate, less than other doses. All somatic embryos from non-irradiated callus could germinate. The germination of somatic embryos produced 72 regenerated plantlets. Dendogram based on morphological observations of 0 Gray regenerated plantlets showed 40% variability, while of 50 Gray were 47% and that of 60 Gray were 46%. Ten regenerated plantlets were chosen based on its variability and growth (P-2, P-8, 50-4, 50-6, 50-15, 50-24, 60-8, 60-10, 60-11 and 60-23). Dendogram based on morphological observation between 10 regenerated plantlets showed 30% variation. Molecular analysis of the 10 regenerated plantlets using three ISSR primers (ISSR-1, ISSR-2 and ISSR-4) produced 17 bands with nine polymorphic bands (52.94%). Dendogram based on molecular analysis between 10 regenerated plantlets and wild type shoots showed 22% genetic variation. In vitro and ex vitro grafting between regenerated plantlets and JC rootstock could accelerate optimal growth of plantlets. Application of ex vitro grafting was more efficient than in vitro grafting. Ex vitro grafting did not need acclimatization stage, where as in vitro grafting still need acclimatization stage before transfer to soil.
Keyword: 

Judul: Fenomena Arus Rabak (Rip Current) Di Kawasan Pantai Panjang, Kota Bengkulu
Abstrak: Tingginya kunjungan wisatawan namun minim pengetahuan tentang kondisi pantai, dapat menyebabkan adanya risiko kecelakaan pantai yang tinggi. Arus rabak adalah salah satu penyebab terjadinya kecelakaan pantai. Tercatat sebanyak 35 kasus terseretnya wisatawan pernah terjadi di Pantai Panjang dari tahun 2009 hingga tahun 2021. Penelitian ini bertujuan menggambarkan kondisi oseanografi pada lokasi yang berpotensi munculnya arus rabak berdasarkan musim, jenis arus rabak, serta menjelaskan karakteristik arus rabak melalui ciri dan proses pembentuk arus rabak. Lokasi penelitian dilakukan di Pantai Panjang, Kota Bengkulu. Analisis arus rabak menggunakan model SWAN, kedalalaman perairan, angin dan citra satelit. Topografi dasar laut pesisir Bengkulu relatif landai. Gelombang signifikan tertinggi terjadi pada bulan Januari 2017 yaitu 0.25 m dengan periode gelombang terlama terjadi pada bulan April 2021 yaitu 1.63 s. Karakteristik tipe gelombang pecah Pantai Panjang yaitu plunging. Fenomena arus rabak kerap terjadi di Pantai Panjang dengan jenis bar-gap rips. Pembentukan arus rabak dipengaruhi oleh kondisi topografi. Arus rabak yang terjadi di Pantai Panjang dapat ditemui s
Keyword: Arus rabak, Gelombang, Pantai Panjang, SWAN, Topografi, Panjang Beach, Rip Current, Topography, Wave