Screening for heat and drought tolerance of rice mutants
2017
Pautin, L.R. | Braceros, R.C. | Padolina, T.F.
Identifying genotypes that can withstand high temperature during flowering stage (anthesis) by maintaining high pollen viability and grain fertility will help breeders develop varieties with improved levels of thermo-tolerance that could produce economic yield even under high temperature. Diverse mutant lines derived from physical and chemical mutagenesis were initially screened for drought stress and leaf blast and the survived lines further assessed for responses to increased temperature. Traditional varieties Ballatinaw and Azucena and a hybrid PSB RC72 H were exposed to Cobalt 60 (gamma rays) while indica varieties IR58 and PSB Rc 4 were mutagenized with ethyl metyl sulfonade (EMS) at 2mg/ml. Nipponbare mutants derived from a Japonica variety, were selected using anther culture technology. After a series of evaluation and selecting mutants with agronomic value were exposed to high temperature ranging from 27.1 deg C to 34.4 deg C during anthesis in field trial and in screen house ranging from 34 deg C to 38.0 deg C. On this basis, 7 heat tolerant mutant lines with 75-100% pollen viability and grain fertility of 40 to 80% were selected and nominated to the National Cooperative Tests (NCT) in 2016 DS. Ballatinaw 30kR -7-2-1-1, Azucena 30kR -62-52, and PSB Rc 72H- 20kR -6-41 (A), IR58- 1, PSB Rc 4-10 (2mg/ml EMS), Nipponbare 28-1 (0.8 EMS), Nipponbare -20km- AC-29-1-1-2. Only IR58- 1, (2mg/ml EMS), ( with 4737 kg/ha, produced better yield than NSIC Rc 222 (4275 kg/ha), tolerant check variety. However, all lines were for further tests including reactions to pests and grain quality. These mutant lines have the potential to adapt to areas affected by high temperature with 35 deg C and can be used as pre-breeding materials / donor germplasm for further improvement.
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