Judul: Development of cytoplasmic male sterile lines derived from three cytoplasm sources and its use on hybrid rice breeding
Abstrak: Hybrid rice is an alternative technology to increase lowland rice productivity. In Indonesia, hybrid rice was developed through three line system that involved three parental lines i.e. cytoplasmic male sterile lines (CMS), maintainer (B) and Restorer (R). CMS as seed parent should have high pollen sterility, be stable, easy to restore, good in agro-morphology and flower behavior, high in combining ability and resistant to pest and diseases. Intensive use of single source of male sterile cytoplasm (i.e. wild abortive or WA) in developing rice hybrids might lead to genetic vulnerability associated with susceptibility to pests and diseases.A series of experiments were conducted to identify new CMS from three cytoplasm sources (WA, Gambiaca and Kalinga) with high pollen sterility, stable and easy to restore. CMS efectivity on seed production and hybrid rice breeding were studied. The results showed that among doubled haploid population,panicle weight had thelargest contribution to grain weight per hill, as shown by high and positive direct effect value (0.7739) and indirect effect value through number of filled grain per panicle (0.6556), therefore the characters could be usedfor selection of good maintainer lines. H36-3-Mb, H36-3-Mc, H36-4-M, H45-3-Da, B1-2-Pb and B2-2-Pb were suitable to be used as new maintainer candidates related to their high number of filled grain and yield. Doubled haploid of B1-1-Mb, B2-1-Db and B2-1-M were resistant to Bacterial Leaf Blight (BLB) strain III. B4-1-Dc line was very resistant (score 0) to BLB strain IV and VIII. Six CMS of wild abortive types, one CMS of Gambiaca and three Kalinga types were bred through successive backcrosses. The three types of CMS lines were semi dwarf and having better flowering characters than the check line. The good flowering behavior of the new CMS lines improved seed set up to 25.90% compared to 2.98% of seed set in IR58025A. The new CMS were more effective and easier in its seed production. Phenotype obstacles such as low panicle exertion and short panicle length were improved through GA3 spraying. It increased the yield of seed. The three types of CMS had spesific combining ability to many restorers and yielded high yielding hybrid combination with good heterosis. The results indicated that the yield of hybrids were controlled by overdominant, dominant x dominantor epistasis gene activity. The best hybrid was derived from WA cytoplasm i.e. BI485A/IR53942 (10.21 t/ha), while the best hybrid derived from Gambiaca cytoplasm was BI625A/SMD11 (9.88 t/ha). BI665A/IR53942 was the best hybrid derived from Kalinga cytoplasm, yielded up to 9.15 t/ha. It can be concluded that new CMS derived from WA, Gambiaca and Kalinga cytoplasm were more efective on seed production and hybrid rice development because of their good flower behaviour, resistance to BLB and good specific combiner with restorers.
Keyword: Seed production, Cytoplasmic male sterile lines, Wild abortive, Gambiaca, Kalinga, Hybrid rice, Oryza sativa L., Graminae, Oryza officinalis

Judul: Performance of Rice Hybrids (Oryza sativa L.) from Crosses of Male Sterile Line and New Plant Type Rice Lines
Abstrak: Padi merupakan salah satu tanaman pangan utama di Indonesia yang berperan penting dalam ketahanan pangan nasional. Peningkatan produktivitas padi melalui pengambangan varietas baru yang adaptif dan berdaya hasil tinggi perlu dilakukan. Sifat agronomi yang baik pada galur padi tipe baru didukung oleh faktor genetik dan lingkungan. Tanaman padi alaminya adalah tanaman menyerbuk sendiri. Oleh karena itu dalam membentuk padi hibrida, penggunaan galur mandul jantan dan galur pemulih kesuburan (restorer) sangat penting. Penelitian dilakukan selama dua musim tanam bulan Mei 2021 hingga Januari 2022 di Kebun Percobaan IPB Sawah Baru dan Laboratorium Mikroteknik Departemen Agronomi dan Hortikultura IPB University, Bogor. Kegiatan dilakukan pada dua musim tanam, yaitu: (1) Pada musim pertama, 15 galur padi tipe baru diuji, serta dilakukan persilangan antara galur mandul jantan sebagai tetua betina dan 15 galur padi tipe baru digunakan sebagai tetua jantan; (2) Pada musim kedua, dilakukan pengujian hibrida yang diperoleh, serta pengujian musim kedua 15 galur tetua padi tipe baru. Kegiatan pengujian 15 galur padi tipe baru selama dua musim dilakukan dengan menggunakan rancangan kelompok lengkap teracak (RKLT) tiga ulangan, serta pengujian hibrida dilakukan dengan RKLT dua ulangan. Hasil penelitian menunjukkan karakter tinggi tanaman, panjang malai, dan umur panen dipengaruhi oleh musim, sedangkan karakter jumlah gabah isi, bobot 1000 butir dan produksi tidak dipengaruhi oleh musim. Genotipe T8 dan T9 memiliki prospek untuk dijadikan galur restorer dalam pembentukan hibrida karena memiliki jumlah gabah isi yang cukup banyak dan didukung dengan karakter- karakter agronomi yang baik. Hal ini juga diperkuat dengan hibrida yang dihasilkan oleh kedua tetua jantan tersebut memiliki bobot gabah per rumpun yang tinggi. Hibrida CMS x IPB189-F-17-3 dan CMS x IPB189-F-132-1-1 memiliki nilai heterosis dan heterobeltiosis dengan nilai positif dan negatif pada masing- masing karakter sesuai dengan tujuan perakitan hibrida. Kedua hibrida tersebut memiliki umur yang relatif genjah dan produktivitas yang relatif tinggi. Hibrida CMS x IPB189-F-17-3 dinilai unggul karena memiliki nilai standar heterosis positif pada karakter bobot gabah per rumpun, jumlah anakan produktif, dan jumlah gabah total., Rice is one of the main food crops in Indonesia that plays an important role in national food security. Increasing rice productivity through the development of new adaptive and high-yielding varieties is necessary. Good agronomic traits in new plant type rice lines are supported by genetic and environmental factors. The rice plant is naturally self-pollinated. Therefore, in establishing hybrid rice, the use of male sterile lines and fertility restorer lines is necessary. The research was conducted during two growing seasons from May 2021 to January 2022 at IPB Sawah Baru Experimental Farm and Microtechnical Laboratory of the Department of Agronomy and Horticulture, IPB University, Bogor. Activities were carried out in two growing seasons, namely: (1) In the first season, 15 new plant type rice lines were tested, as well as crosses between male sterile lines as female parents and 15 new plant type rice lines used as male parents; (2) In the second season, the hybrids obtained were tested, as well as the second season testing of 15 new plant type parents. The testing of 15 new plant type rice lines for two seasons was carried out
Keyword: male parent line, CMS, food resilience, heterobeltiosis, heterosis, productivity, rice hybrid, season, superior varieties

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf