Exploiting rice heterosis for rainfed drought prone environments
2012
Rebong, A.T.I.O. | Ordonio, J.L. | Medrano, Y.D., Philippine Rice Research Inst. Isabela, Malasin, San Mateo, Isabela (Philippines)
Rainfed lowland rice has recently received the attention it deserves from the rice scientific community. The yield in rainfed lowland areas is lower compared to yields in irrigated areas since they are very prone to drought during the dry season, hence cultivated only during the wet season when rains are predominant. However, rains are sometimes still limiting during the wet season. Heterosis which exists in hybrid rice offers yield advantage of at least 15%, thus growing hybrid rice under rainfed conditions could give a major contribution to the increasing demand for more rice. In 2011 dry season, the authors have screened 277 test hybrids, 32 RxR recombinants for drought stress and produced 116 F1 testcrosses. From the 277 test hybrids, the authors have identified 66 partial maintainers, 27 partial restorers and 9 restorers based on correlated results of pollen and spikelet fertility test. The 9 identified restorers will be used in the on-going hybrid rice project for rainfed. The authors have selected 10 RxR entries from the 32 RxR crosses based on desired traits under drought stress and advanced them to the next generation for further evaluation. In 2011 wet season, yield performance evaluation of newly released and promising hybrids was conducted in three rainfed drought-prone sites within Isabela. Results had PhilRice-bred Mestiso 19 with the highest yield at 2726 kg/ha followed by PhilSCAT 6-1 H, Mestiso 1, PhilSCAT 6-1 H and Mestiso 20. Performance evaluation for newly released and promising hybrids, stage 1 trial for drought and selection for good recombinants in the advance generation of RxR crosses will be continued in 2012 dry season.
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