Breeding cool rice lines for got climes
2011
Laza, M.A. | Redona, E.D. | Sierra, S.N., International Rice Research Inst., DAPO Box 7777, Metro Manila (Philippines). Plant Breeding, Genetics and Biochemistry Div. | Manigbas, N.L., Philippine Rice Research Inst,, Science City of Muñoz, Nueva Ecija (Philippines)
High daytime and nighttime temperatures threaten world rice productivity. Daytime temperatures greater than 35 deg C during flowering increases grain sterility leading to low yield. Breeding rice varieties tolerant to high daytime temperature is essential for future rice production under a climate change scenario. At the International Rice Research Institute (IRRI), development of heat-tolerant rice was initiated in the 2007 dry season (DS). Varieties reported to be tolerant to heat, including those from hot countries, were used as parents in the initial crosses and analyzed for genetic diversity using molecular markers. In 2008 DS, 34 F2 populations were planted at the IRRI pedigree nursery and during 2009 DS about 1800 lines were selected for high temperature screening during flowering in Tamil Nadu, India and Ahwaz, Iran using a modified shuttle breeding strategy. Plants with the least grain sterilities were selected from those lines in Iran and India. At the same time, plant selections and generation advance were simultaneously done at IRRI. Based on the information on the best lines selected in the hot sites, sister lines at IRRI were advanced and tested under controlled conditions in the phytotron (38 deg C during flowering stage) at the F6 generation. During 2010 wet season (WS), the best F7 lines were entered in an Observational Yield Trial (OYT) at IRRI. Estimated yields of these lines were as high as 7.5 tons/ha. The elite line 1R 10C145 yielded higher than the check varieties PSB RC82 and 1R6 (heat tolerant selection from Pakistan). All lines are being screened again during the 2011 DS at IRRI and at the Philippine Rice Research Institute (PhilRice) under field condition and again in the phytotron at IRRI for heat tolerance reconfirmation. The best lines will nominated to IRRI's new Multi environment Varietal Testing (MET) program beginning 2012 DS.
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