Judul: Flowering biology and parthenocarpy of citrus derived from somatic hybridization of Mandarin Satsuma (Citrus unshiu Marc.) and Siam Madu (Citrus nobilis Lour.)
Abstrak: Fusi protoplas antara Mandarin Satsuma (Citrus unshiu Marc.) dan Siam Madu (Citrus nobilis Lour.) diharapkan menghasilkan buah dengan rasa yang enak dan mempunyai biji sedikit, namun kenyataannya menghasilkan hibrida dengan variasi genetik yang tinggi. Tujuan penelitian ini adalah mendapatkan informasi biologi pembungaan dan pembentukan buah serta sifat partenokarpi jeruk hasil fusi protoplas antara Mandarin Satsuma dan Siam Madu. Penelitian dilaksanakan di KP Pacet BB Biogen, Cianjur (1150 m dpl), selama Agustus 2019 – Juli 2020. Bahan penelitian berupa 15 galur jeruk hasil fusi protoplas (Mandarin Satsuma dan Siam Madu), masing-masing terdiri atas 5 tanaman (umur ± 2 tahun), yang diperbanyak secara okulasi dengan batang bawah JC (okulasi pada bulan Juni 2017). Biologi pembungaan diamati secara deskriptif mencakup morfologi bunga, perkembangan bunga dan buah, viabilitas serbuk sari dan reseptivitas stigma. Pembentukan buah dan biji dari bunga tanpa penyerbukan, penyerbukan sendiri dan silang untuk mendapatkan informasi adanya sifat partenokarpi pada tanaman hasil fusi protoplas. Hasil pengamatan menunjukkan bahwa morfologi bunga galur-galur tanaman jeruk hasil fusi protoplas cukup beragam dan mewarisi karakter kedua tetuanya. Fase pembentukan bunga hingga buah masak bervariasi antar galur, dengan lama perkembangan yang berkisar 212 – 316 hari. Media yang tepat untuk pengecambahan serbuk sari menggunakan media PGMm. Viabilitas serbuk sari tertinggi dan masa reseptif stigma tercapai pada saat bunga mekar sempurna. Galur FS 25 menghasilkan serbuk sari dengan viabilitas yang paling rendah dan buah tidak terbentuk tanpa penyerbukan. Penyerbukan sendiri FS 25 dan penyerbukan silang dengan FS 84 dan FS 89 menghasilkan persentase buah tanpa biji tertinggi. Penyerbukan antar galur yang cross-compatible diperlukan untuk produksi buah tanpa biji pada galur dengan potensi partenokarpi stimulatif yang kuat. FS 25 memiliki karakter partenokarpi stimulatif, dan FS 84 dan FS 89 dapat digunakan sebagai sumber serbuk sari untuk menstimulasi pembentukan buah tanpa biji., The somatic hybridization between Mandarin Satsuma (Citrus unshiu Marc.) and Siam Madu (Citrus nobilis Lour.) is expected to produce seedless fruit with good taste, but in fact produces hybrids with high genetic diversity. The purpose of this study was to obtain information on flowering biology and fruit formation as well as the parthenocarpic characters of the genotypes from somatic hybridization between Mandarin Satsuma and Siam Madu. The research was carried out at Pacet Experimental Station, BB Biogen, Cianjur (1150 m asl), during August 2019-July 2020. The research materials were 15 citrus lines resulting from somatic hybridization (Mandarin Satsuma and Siam Madu), each consisting of 5 plants (± 2 years old), which were propagated by grafting with JC rootstocks (grafting at June 2017). Flowering biology was observed descriptively including flower morphology, flower and fruit development, pollen viability and stigma receptivity. Development of fruit and seeds from flowers without pollination, self-pollination and cross-pollination were observed to invertigate the existence of parthenocarpy in plants resulting from somatic hybridization. The result showed that the flower morphology of citrus somatic hybridization lines varied and inherits the characters of both parents. The development from flower bud until fruit ripening varied among lines, ranged 212-316 days. The modified PGM was the most suitable for citrus pollen germination. The pollen viability was the highest at blooming during which
Keyword: BBCH, numbers of petal, stimulative parthenocarpy, self-pollinated, pollen viability

Judul: Morphological Characterization and Fruit Formation in Polyploid Citrus Plants Resulting from Somatic Hybridization and Endosperm Culture
Abstrak: Target pemuliaan tanaman jeruk adalah mendapatkan buah jeruk seedless yang lebih disukai oleh konsumen. Pembentukan buah jeruk seedless dapat terjadi akibat adanya sifat partenokarpi alami dan perpasangan tiga set kromosom yang tidak seimbang pada buah triploid. Karakterisasi morfologi perlu dilakukan untuk mengidentifikasi karakter-karakter unggul yang tampak, terutama karakter yang berkaitan dengan pembungaan dan pembentukan buah untuk memastikan apakah galur jeruk poliploid khususnya triploid dapat menghasilkan buah seedless. Penelitian yang dilakukan terdiri dari karakterisasi morfologi habitus, daun, bunga, buah, dan biji, serta induksi pembentukan buah dan biji pada galur jeruk poliploid hasil hibridisasi somatik dan kultur endosperma. Hasil penelitian menunjukkan bahwa hampir semua karakter morfologi galur hasil hibridisasi somatik dan kultur endosperma mewarisi tetua jeruk siam madu, kecuali beberapa karakter morfologi bunga yang mewarisi kedua tetuanya, yaitu jeruk siam madu dan mandarin satsuma. Perlakuan penyerbukan sendiri secara nyata dapat meningkatkan persentase pembentukan buah seedless pada galur jeruk poliploid, baik pada galur hasil hibridisasi somatik maupun hasil dari kultur endosperma. Galur FS25 berpotensi untuk dikembangkan menjadi salah satu galur jeruk seedless karena memberikan hasil persentase pembentukan buah seedless tertinggi dibanding galur lainnya. Galur MT12 menunjukkan adanya perkembangan biji triploid yang terbentuk secara spontan., The target of citrus breeding is to obtain seedless citrus fruit that are preferred by consumers. The formation of seedless citrus fruits can occur due to the natural parthenocarpy and the unbalanced pairing of three chromosome sets in triploid fruits. Morphological characterization needs to be done to identify the superior characters, especially those related to flowering and fruit formation to determine whether polyploid citrus lines, especially triploids can produce seedless fruit. The research consisted of characterization the morphology of the habitus, leaves, flowers, fruit and seeds, as well as the formation of fruit and seeds in the polyploid citrus line resulting from somatic hybridization and endosperm culture. The results showed that almost all morphological characters of the lines resulting from somatic hybridization and endosperm culture were inherited from the parents of siam madu, except for several morphological characters of flowers inherited from the parents of siam madu and satsuma mandarin. The self-pollination treatment significantly increased the percentage of seedless fruit formation in the triploid citrus line. The FS25 line can be developed into one of the seedless citrus lines because the percentage of seedless fruit formation higher than other lines. The MT12 line showed triploid seed development which spontaneously formed.
Keyword: endosperm culture, morphological characterization, pollination, seedless fruit, somatic hybridization

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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