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: BREEDING OF HYBRID RICE RESISTANT TO BACTERIAL LEAF BLIGHT AND GOOD GRAIN
Abstrak: Breeding new rice variety does not always give adequate results, therefore it is necessary to develop methods for rice varieties breeding. Hybrid rice is an alternative to increase the productivity of irrigated rice in Indonesia. The new hybrid rice varieties are expected to have high yield potential, resistant to bacterial leaf blight, and have good rice quality. The use of other cytoplasmic CMS types (Gambiaca and Kalinga) aimed to anticipate genetic vulnerability and to increase the diversity of hybrid rice in Indonesia. The objectives of this study were (1) to determine the effect of female parents with different cytoplasmic sources on hybrid seed yield, (2) to select the parental lines of hybrid rice that had good combining ability and heterosis value, (3) to obtain information on the parents and hybrid rice which had BLB resistance and good grain quality, (4) to obtain hybrid rice with high yield, resistant to bacterial leaf blight and good grain quality. The research stages of hybrid rice breeding from three different cytoplasmic sources and had bacterial leaf blight resistant were: (1) Hybrid rice seed production for research materials and to evaluate the ability of seed production for each combination of hybrid rice. This experiment was carried out by crossing CMS parental with restorers to obtain F1 seeds. In the second experiment, there were two activities (2a) combining ability and heterosis value of hybrid rice, (2b) grain and rice quality evaluation. The third experiment was (3) the evaluation of hybrid rice for resistance to bacterial leaf blight. The research was conducted at the Indonesia Center fo Rice Research (ICRR), and in farmer field in Karawang, West Java from March 2021 to March 2022. The first stage is hybrid rice seed production of three cytoplasmic CMS types with 10 restorers to determine F1 seeds production ability which had a good hybrid rice combination. The highest hybrid rice seed yield was obtained from a combination of hybrid rice from female parents GMJ15A, and male parents PK90. The average F1 seed yield of female parental of the Gambiaca type GMJ15A line (1.03 ton ha-1 ) was equivalent to the WA type GMJ12A line (0.85 ton ha-1 ) and was significantly higher than the Kalinga type GMJ14A line (0.51 ton ha-1 ). The male parent (restorer) with the highest average seed yield was PK90 (1.36 ton ha-1 ). The number of grain contents per panicle and the outcrossing rate were positively correlated with the yield of hybrid rice seeds produced. The second experiment was a line x tester to study on the effect of female parents (CMS) and restorers to obtain new hybrid rice combinations with different cytoplasm. The objective of the study was to select the parental lines of hybrid rice that had good combining ability, heterosis and to obtain information on the parents and hybrid rice with high yields. The combined analysis of variance showed a significant effect between locations and hybrid rice on yield components. Results showed that the line parent GMJ14A, testers CRS1301 and CRS1310 had the best general combining ability (GCA). The combination of hybrid rice GMJ12A/R3,
Keyword: bacterial leaf blight resistance, CMS, combaining ability, grain quality and rice quality, heterosis, hybrid rice, restorer

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