Abstract. Hairmansis A, Yullianida, Supartopo, Jamil A, Suwarno. 2017. Variability of upland rice genotypes response to low light intensity. Biodiversitas 18: 1122Biodiversitas 18: -1129. Plantation areas have a great potential to be utilized for upland rice production through intercropping. One of major constraints in the cultivation of upland rice as intercropping is low light intensity caused by shading. Improvement of rice varieties for shading tolerance is therefore important to increase rice production in upland areas. The objective of this study was to investigate the variability of upland rice genotypes responses to shading and identify the best genotypes for intercropping rice cultivation. Thirty-eight upland rice breeding lines, the shading tolerant rice variety Jatiluhur, and the shading susceptible rice variety IR64 were evaluated for their response to low light intensity in the greenhouse and the field. Greenhouse screening was conducted to determine their shading tolerance in vegetative stage while evaluation in the field was performed to evaluate their agronomic performance under 55% shading and normal conditions. Variation in upland rice genotypes on low light stress was revealed both in greenhouse and field trials. In the greenhouse trial, 12 genotypes showed higher survival rate compared to tolerant rice variety Jatiluhur. Field evaluation demonstrated that 55% shading increased plant height, reduced productive tiller number, delayed flowering time, increased spikelet sterility and reduced grain yield. Upland rice breeding line B11908F-TB-3-WN-1 showed high yield relative in shading condition compared to normal condition and had high-stress tolerance index (STI) which indicated the genotype was tolerant to shading.

Usaha pertanian padi gogo yang mencakup luasan produksi sekitar 1.15 juta ha merupakan penyangga penting ketahanan pangan nasional. Namun demikian peningkatan produksi padi di lahan kering terhambat oleh berbagai cekaman lingkungan baik berupa cekaman biotik maupun abiotik. Untuk mendukung keberlanjutan produksi padi di lahan tersebut sekaligus mendukung peningkatan produksi beras nasional dibutuhkan varietas unggul yang adaptif dengan kondisi lingkungan di lahan tersebut. Program pemuliaan padi gogo bertujuan untuk merakit varietas unggul padi gogo yang memiliki potensi hasil tinggi dan adaptif terhadap berbagai cekaman lingkungan dengan memanfaatkan biodiversitas dalam gene pool padi khususnya dari kelompok Oryza sativa. Tahap awal dalam perakitan varietas padi gogo adalah persilangan untuk menggabungkan sifat-sifat yang diinginkan ke dalam satu populasi pemuliaan. Persilangan dilakukan dengan metode silang tunggal, silang puncak, silang ganda dan silang balik. Populasi hasil persilangan selanjutnya menjadi bahan seleksi berbagai sifat penting untuk padi gogo dengan metode bastar populasi dan metode pedigree. Dengan memanfaatkan biodiversitas plasma nutfah pada tahun 2014 telah diperoleh beragam populasi baru hasil persilangan untuk perbaikan sifat padi gogo. Populasi tersebut menjadi materi genetik yang sangat berharga untuk dilanjutkan dalam program seleksi untuk mendapatkan varietas unggul baru padi gogo.

Sustainability of rice (Oryza sativa L.) production in high-altitude tropical upland is challenged by various abiotic and biotic problems. The main problems include low temperatures and blast disease. Farmers in high-altitude tropical uplands of Indonesia are still growing traditional rice varieties due to the absence of improved adaptive varieties. Development of improved varieties which are adapted to the high-altitude upland environment is therefore needed to increase productivity. This study aimed to investigate the interaction of genotype and environment of upland rice varieties across ten high-altitude upland locations in Indonesia and to determine their adaptability in the target areas. In addition, screening on blast disease and grain quality analysis was performed to characterize the genotypes. Significant interaction effects between genotype and the environment were observed for all agronomic characters. Genotype adaptability was determined based on the regression coefficient of grain yield and the environmental index. Genotypes such as B14168E-MR-10 adapted well in locations with low environmental indexes. In contrast, genotypes such as B11592F-MR-23-2-2 adapted well in locations with high environmental indexes. Screening using ten rice blast races showed that upland rice genotypes had a broad spectrum of resistance. Most of the genotypes had intermediate amylose content in the grains. Recently, the lines B14168E-MR-10 and B11592F-MR-23-2-2 have been approved to be released as new, improved rice varieties for high-altitude upland in Indonesia, namely Luhur 1 and Luhur 2, respectively. Both varieties are expected to be adopted by farmers in high-altitude upland to increase rice productivity in this environment.

Kedaulatan pangan, terutama untuk komoditas padi, menjadi sorotan di Indonesia. Oleh karena itu diperlukan upaya peningkatan produksi, salah satunya dengan pengembangan pertanaman padi ke lahan marginal. Khusus untuk padi gogo dapat dikembangkan sebagai tanaman sela di lahan perkebunan dan perluasan tanam ke dataran tinggi. Upaya tersebut memerlukan varietas padi gogo yang toleran naungan dan dataran tinggi, dimana baru satu varietas unggul padi toleran naungan yang dilepas, yaitu Jatiluhur, sedangkan untuk padi toleran dataran tinggi belum ada. Saat ini, sumber genetik yang dapat dijadikan sebagai donor sifat padi gogo toleran naungan dan dataran tinggi telah teridentifikasi yang bertujuan untuk dijadikan sebagai tetua persilangan dalam rangka penggabungan sifat-sifat yang diinginkan. Metode persilangan yang dilakukan meliputi silang tunggal (single cross), silang ganda (double cross), silang balik (backcross), dan silang puncak (top cross). Satu-satunya sumber sifat atau donor tetua untuk sifat toleransi terhadap naungan hanya didapatkan dari varietas Jatiluhur, sedangkan untuk sifat toleran dataran tinggi didapatkan dari varietas lokal Sigambiri Putih, Sigambiri Merah, Srintil, Padi Mandailing, padi sawah Sarinah, dan galur B13604E-TB-59. Pada tahun 2015 telah diperoleh sebanyak 24 kombinasi persilangan untuk tujuan toleran naungan, terdiri atas 6 kombinasi hasil persilangan tunggal, 9 kombinasi hasil persilangan puncak, 7 kombinasi hasil persilangan balik, dan 2 kombinasi hasil persilangan ganda. Adapun persilangan dengan tujuan padi gogo toleran dataran tinggi telah diperoleh sebanyak 34 kombinasi yang terdiri atas 15 kombinasi persilangan tunggal, 14 kombinasi persilangan puncak, 1 kombinasi persilangan balik, dan 4 kombinasi persilangan ganda. Kombinasi persilangan tersebut sebagian besar telah disilangkan dengan kombinasi sifat unggul lainnya, seperti potensi hasil tinggi, tahan hama/penyakit utama, mutu beras baik, serta toleran kekeringan dan keracunan aluminium sebagaimana yang sering menjadi kendala dalam pertanaman padi gogo. Kata kunci: Dataran tinggi, naungan, padi gogo, persilangan Abstract. Yullianida, Hairmansis A, Supartopo, Suwarno. 2016. Genetic sources for basic population development of upland rice tolerant to shading and high altitude. Pros Sem Nas Masy Biodiv Indon 2: 175-181. Food sovereignty, especially for rice commodity, is being the main spotlight in Indonesia. Therefore, we need to increase production, one of them is the development of rice cultivation into marginal land. Especially for upland rice can be developed as an intercropping plant in the fields and plant expansion to highland. This effort requires the upland rice varieties that tolerant to shade and high altitude, where the only one rice variety that tolerant to shade was released, namely Jatiluhur, while for rice variety that tolerant on highland had not yet. Currently, the genetic resources that can be used as a donor of upland rice which tolerant to shade and high altitude had been identified which aim to be used as cro...