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: Pembentukan tanaman triploid jeruk siam simadu (Citrus nobilis Lour.) melalui kultur endosperma
Abstrak: Seedless fruit is one of the criteria necessary to improve the quality of citrus. Traditionally, formation of seedless citrus plant is difficult due to the barriers of sterility gametes which are owned by gene sources of seedless citrus to be transfer to Simadu tangerine. The formation of a triploid plant from a interploidy crossing could not be done because tetraploid citrus plants is not available. Triploid citrus is unable to form the fertile seeds, so it can be used as an alternative to the production of seedless fruits. In vitro, formation of triploid plant can be aimed by regenerate endosperm tissue that is naturally triploid. Shoots obtained from endosperm tissue expected also to be a triploid plant. The aim of this research was to obtain triploid Simadu tangerine derived from culture of endosperm tissue. There were four stages of research conducted to accomplish the research objective. Study of Developmental stage of endosperm tissue of Simadu tangerine. Research conducted to determine the developmental of endosperm tissue that could be cultured in vitro. Plant materials observed was a young fruit from 2 to 14 weeks after anthesis (WAA). The observation was made against fruit morphology, fresh and preserved slice of seeds. The observation was performed with a stereo and inverted microscope. The results showed that endosperm tissues could be isolated from the fruit of 10-14 weeks after anthesis. This tissue had formed cell walls and gradually form compactendosperm tissues and could be isolated and separated from zygotic and nucellar embryos. Induction of somatic embryogenesis and formation of triploid plants derived from varied developmental stages of endosperm tissue of Simadu tangerine (Citrus Nobilis Lour). Research conducted to obtained in vitro technique that could be regenerated endosperm tissue to forming triploid plants. A plant material was an endosperm tissue that was isolated from 10-14 WAA fruit. Endosperm tissues isolated with a binocular microscope with 40x magnification. The results showed that the endosperm tissues from 11-13 WAA could be induced the formation of embryogenic callus with best response shown by endosperm tissue that was 13 WAA and cutured on MS medium modified by MW vitamine. Mixoploid Calli was resulted from the endosperm tissues so the regeneration should be done by somatic embryogenesis. Somatic embryogenesis could be avoiding formation of mixoploid plants. Maturation of somatic embryos cultured on solid medium and 3 g L-1 phytagel without addition of plants growth regulators. Plantlets sub cultured on the same media with the addition of 2.5 mg L-1 GA for shoots elongation. Clonal Multiplication of in vitro shoots that regenerated from endosperm tissue of Simadu tangerine. The research was done to obtain the medium formulation and population of in vitro shoots that regenerated from endosperm tissue. Plant material was shoots that obtained from the somatic embryogenesis derived from endosperm of tissue. Shoots cultured on multiplication medium and observed formation of normal shoots and directly of adventives shoots. The results showed that the MT medium (medium for in vitro culture of citrus), was growth of abnormal shoots higher than a MS medium by vitamin MW modified. Addition of Kinetin, BA and NAA
Keyword: Citrus nobilis Lour, Simadu tangerine, somatic embryogenesis, citrus haploid plants, seedless citrus

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