Initial Study of the Response of Ultra Early Maturing Rice Genotypes to Drought Stress Conditions in Vegetative and Generative Phase
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Balai Besar Penelitian dan Pengembangan Bioteknologi dan Sumberdaya Genetik Pertanian
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Perubahan iklim global menyebabkan meluasnya daerah dengan risiko kekeringan. Cekaman kekeringan pada tanaman padi terutama terjadi di lahan gogo, tadah hujan, dan irigasi terbatas. Perakitan varietas yang cocok untuk daerah-daerah tersebut diharapkan dapat meningkatkan hasil padi secara nyata. Padi umur genjah efektif untuk mengantisipasi cekaman kekeringan fase generatif di akhir musim hujan melalui mekanisme escape. Namun demikian, kekeringan yang tidak dapat diprediksi yang dapat terjadi pada awal, tengah, maupun akhir musim tanam memerlukan varietas yang betul-betul toleran terhadap cekaman kekeringan. Penggabungan sifat umur genjah dan toleran kekeringan diharapkan mampu mengantisipasi kondisi cekaman kekeringan. Penelitian ini bertujuan untuk mengetahui respons 23 genotipe padi umur genjah yang terdiri atas 3 varietas unggul, 10 varietas lokal, dan 10 galur introduksi yang diberi perlakuan optimum, tercekam kekeringan pada fase vegetatif (diairi hingga 7 hari setelah tanam dan diairi kembali ketika cek peka mengering), dan generatif (diairi hingga 28 hari setelah tanam dan diairi kembali hanya jika cek peka mengering). Penelitian dilakukan di Kebun Percobaan BB Padi di Sukamandi pada MK 2009. Genotipe yang diuji diberi perlakuan pengairan tersebut di atas tanpa ulangan untuk mengetahui secara deskriptif kondisi karakter-karakter penting genotipe-genotipe yang diuji pada ketiga kondisi pengairan tersebut. Hasil penelitian menunjukkan bahwa berdasarkan karakter hasil, Indeks Cekaman Kekeringan (IKK; Drought Sensitifity Index, DSS), Nilai Relatif (Relative Values, RV), dan keragaan agronomi, galur OM 1490 teridentifikasi toleran terhadap cekaman kekeringan fase vegetatif dan generatif dengan hasil 28,17 g/tanaman, 24,11 g/tanaman, dan 24,72 g/tanaman pada kondisi optimum, tercekam vegetatif, dan generatif. OM 1490 telah dilepas sebagai varietas Inpari 13 pada tahun 2010 dan varietas ini telah digunakan dalam kegiatan pemuliaan tanaman menghasilkan galur-galur harapan yang baru. AbstrakGlobal climate change has caused the spread of drought prone areas. Drought stress for rice mostly happen in upland, rainfed, and limited irrigation lowland areas. Development of varieties suitable for those areas would significantly increase rice yield. Early maturing genotypes are useful to anticipate predictable early or terminal drought by escape mechanism. Nevertheless, unpredictable drought happening during early, mid season and final planting season results in the need of genuinely droughttolerant genotypes. Combining early maturing and drought tolerant seems to be highly powerful to anticipate drought. This research was aimed to study the response of 23 early maturing rice genotypes consisting of 3 released varieties, 10 local varieties, and 10 introduced lines. The genotypes were exposed to vegetative (watered until 7 days after transplanting and rewater when the susceptible check was drying) and generative phase (watered until 28 days after transplanting and rewatered only if susceptible check was drying), drought stress conditions, and also optimum condition. The experiment was conducted in ICRR Experimental Station in Sukamandi during Dry Season (DS) of 2009. The genotypes were treated with three watering conditions mentioned above without replication to initially see the descriptive statistics of some agronomic traits of the genotypes under the mentioned conditions. The results showed that based on yield, Drought Sensitifity Index (DSS), Relative Values (RV), and agronomic performance, OM 1490 had been identified as tolerant to vegetative and generative drought stresses. It yielded 28.17 g/plant, 24.11 g/plant, and 24.72 g/plant at optimum, vegetative, and generative drought condition, respectively. OM 1490 had been released as Inpari 13 in 2010 and it had beed utilized for further breeding effort resulting new promising lines.