A BC(2)F(2) population developed from an interspecific cross between Oryza sativa (cv IR64) and O. rufipogon (IRGC 105491) was used in an advanced backcross QTL analysis to identify and introduce agronomically useful genes from this wild relative into the cultivated gene pool. The objectives of this study were: (1) to identify putative yield and yield component QTLs that can be useful to improve the elite cultivar IR64; (2) to compare the QTLs within this study with previously reported QTLs in rice as the basis for identifying QTLs that are stable across different environments and genetic backgrounds; and (3) to compare the identified QTLs with previously reported QTLs from maize to examine the degree of QTL conservation across the grass family. Two hundred eighty-five families were evaluated in two field environments in Indonesia, with two replications each, for 12 agronomic traits. A total of 165 markers consisting of 131 SSRs and 34 RFLPs were used to construct the genetic linkage map. By employing interval mapping and composite interval mapping, 42 QTLs were identified. Despite its inferior performance, 33% of the QTL alleles originating from O. rufipogon had a beneficial effect for yield and yield components in the IR64 background. Twenty-two QTLs (53.4%) were located in similar regions as previously reported rice QTLs, suggesting the existence of stable QTLs across genetic backgrounds and environments. Twenty QTLs (47.6%) were exclusively detected in this study, uncovering potentially novel alleles from the wild, some of which might improve the performance of the tropical indica variety IR64. Additionally, several QTLs for plant height, grain weight, and flowering time detected in this study corresponded to homeologous regions in maize containing previously detected maize QTLs for these traits.

One of the efforts to increase rice yield is through hybrid rice production. Hybrid rice has now been commercialized in Indonesia. The parental lines of the hybrids developed in Indonesia mostly came from introduced lines. Those lines were more susceptible to stresses, especially to pests and diseases, that make the yield of the hybrid fluctuated and wasn't stable. Hence, it is needed to develop hybrid variety using Indonesian parental line which were well adapted to Indonesia. Therefore, identification of those lines is needed. ABSTRAKSalah satu upaya untuk meningkatan hasil padi adalah dengan penanaman varietas hibrida. Saat ini di Indonesia mulai menerapkan teknologi padi hibrida secara komersial. Padi hibrida yang berkembang di Indonesia berasal dari galur-galur tetua hasil introduksi. Biasanya galur-galur tetua introduksi lebih peka terhadap perubahan kondisi lingkungan terutama hama dan penyakit, sehingga hasilnya lebih berfluktuasi dan tidak stabil. Dengan demikian perlu dirakit varietas padi hibrida dengan menggunakan galur padi hasil pemuliaan Balai Penelitian Tanaman Padi (Balitpa) yang telah beradaptasi baik di Indonesia. Galur-galur tersebut perlu diidentifikasi sebelum digunakan sebagai tetua padi hibrida dengan cara diuji silang. PENDAHULUANSalah satu upaya dalam peningkatan hasil padi adalah dengan penanaman varietas hibrida. Saat ini Indonesia mulai menerapkan teknologi padi hibrida secara komersial. Untuk membentuk padi hibrida diperlukan penggunaan galur mandul jantan dalam persilangan. Galur mandul jantan yang paling banyak digunakan di beberapa negara yang mengembangkan padi hibrida adalah galur mandul jantan sitoplasmik (cytoplasmic male-sterile line) atau disebut juga sistem tiga galur karena melibatkan tiga galur tetua dalam persilangan, masing-masing galur mandul jantan sitoplasmik, galur pemulih kesuburan, dan galur pemelihara mandul jantan (Yuan 1998).Padi hibrida yang berkembang di Indonesia, baik yang dihasilkan oleh institusi pemerintah maupun swasta, berasal dari galur-galur tetua introduksi. Biasanya varietas/galur introduksi lebih peka terhadap perubahan kondisi lingkungan, terutama hama penyakit, sehingga hasilnya lebih berfluktuasi dan tidak stabil. Dengan demikian perlu dirakit varietas padi hibrida yang lebih sesuai dengan kondisi lingkungan di Indonesia. Hal tersebut dapat dilakukan dengan menggunakan varietas/galur yang telah beradapsi di Indonesia sebagai bahan genetik. Bahan genetik tersebut berupa varietas unggul dan galur-galur yang dihasilkan dalam program pemuliaan padi konvensional (inbrida).