Percobaan lapang dan rumah kasa telah dilakukan pada MK 2009 di Indramayu dan Sukamandi, Jawa Barat. Percobaan lapang dilaksanakan pada lahan petani di Desa Cilandak, Kecamatan Anjatan, Kabupaten Indramayu, dari bulan Mei sampai Oktober 2009. Percobaan ini ditata menggunakan rancangan acak kelompok dengan tiga ulangan. Genotipe padi yang diuji adalah AS996, OM5240, BP5478-2F-KN-11-2-B, Inpari 10, Inpari 1, Silugonggo, dan Dodokan. Perlakuan terdiri atas tiga kondisi pengairan, yaitu (a) normal (diairi 100%); (b) setengah kering (diairi 75%), pertanaman diairi sampai umur satu bulan setelah tanam dan selanjutnya diairi seminggu sekali sampai menjelang panen, dan (c) kering (diairi 50%), pertanaman diairi sampai umur satu bulan setelah tanam, selanjutnya tidak diairi sampai panen. Karakter tanaman padi yang diamati adalah persentase gabah hampa, bobot gabah, indeks kepekaan terhadap kekeringan (S), dan indeks keunggulan genotipe (Pi). Percobaan rumah kasa dilaksanakan di Balai Besar Penelitian Tanaman Padi, Sukamandi, pada bulan Juli-Oktober 2009. Percobaan pot ini menggunakan rancangan acak lengkap dengan tiga ulangan dengan menggunakan genotip padi yang sama dengan percobaan lapangan. Perlakuan terdiri atas tiga kategori pasokan air, yaitu minimal (4.000 m3/ha/musim), optimal (5.500 m3/ha/musim) dan lebih dari cukup (7.000 m3/ha/musim). Karakter tanaman padi yang diamati adalah bobot gabah (g/pot GKG), persentase gabah isi, tinggi tanaman, dan umur tanaman berbunga. Hasil penelitian menunjukkan bahwa cekaman air pada saat pembungaan meningkatkan kehampaan malai 25,6-34,3% dan menurunkan hasil 11,3-23,2%. Genotipe AS996, OM5240, dan BP5478-2F-KN-11-2-B toleran terhadap kekeringan, dan memberikan hasil lebih tinggi daripada Inpari 10, Inpari 1, Silugonggo, dan Dodokan. Pada kondisi tercekam kekeringan, pada kondisi kekeringan yang tidak ekstrim dengan kadar air tanah 41,3-51,7%, hasil ketiga genotipe tersebut tidak berbeda nyata dengan pada kondisi normal (6,66-7,27 t/ha). Genotipe AS996 dan OM5240 selain toleran kekeringan juga efisien dalam penggunaan air selama pertanaman.
Early Maturing Rice Genotypes Rice Tolerance to Limited Water Supplies. Field and screen house experiments were conducted in 2009 in Indramayu and Sukamandi. The field experiments was carried out at farmer\'s field in the Cilandak village, Anjatan District, Indramayu Regency from May to October 2009. Nine rice genotypes (AS996, OM5240, BP5478-2F-KN-11-2-B, Inpari 10, Inpari 1, Silugonggo, dan Dodokan) were tested. The experiment was arranged in a randomized block design with three replications. The treatments were: (a) fully irrigated (100% irrigated); (b) half-dry (75% irrigated), irrigation water was given until one month after planting, followed with weekly irrigation until crop harvest, and (c) dry (50% irrigated), irrigation water was given until one month after planting, then no more irrigation was given until harvest. The plant characters observed were: percentage of empty grain per panicle, grain weight per unit area, drought sensitivity index (S), and genotype superiority index (Pi). The screenhouse experiment was conducted in pots at the Rice Research Institute, Sukamandi, from July to October 2009, arranged in a completely randomized block design with three replications. The rice genotypes tested were the same as those in the field trial, The treatments wer three categories of water supply, namely minimum (4,000 m3/ha/season), optimal (5,500 m3/ha/season) and excessive (7,000 m3/ha/season). The plant characters observed were: grain weight (g/pot), percentage of filled grains/panicle, plant height, and age of flowering. The results showed that water stress during flowering stage increased percentage of empty grains from 25.6% to 34.3% and decreased grain yields from 11.3% to 23.2%. Genotypes AS996, OM5240, and BP5478-2F-KN-11-2-B were tolerant to drought, and gave higher yields than Inpari 10, Inpari 1, Silugonggo, and Dodokan. Under drought stress conditions, when the drought conditions were not extreme with soil moistures of 41.3% to 51.7%, yields of the three genotypes were not significantly tolerances from those under the normal condition (6.66 to 7.27 t/ha). Besides drought tolerant, genotypes AS996 and OM5240 were also efficient in using water during the crop growth.
