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Submitted to: Cereal Research Communications
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/20/2004 Publication Date: 12/10/2004 Citation: Zeng, L. 2004. Response and correlated response to salt tolerance selection in rice by yield parameters. Cereal Research Communications. 32(4):477-484. Interpretive Summary: One of the major reasons for the limited success in salt tolerance breeding is the lack of reliable selection criteria in the screening for salt tolerance and understanding genetic basis of salt tolerance. This study was designed to determine the responses of yield parameters in rice plants to the selection for salt tolerance. Genetic populations were developed from crosses between 'M-202' (salt-sensitive) and 'Agami' (moderately salt-tolerant) and grown in the greenhouse under salt stress (NaCl and CaCl2, 5:1 molar concentration) in 2001. Selections were made in the crossing populations for salt tolerance. The progenies of the selected plants were evaluated for salt tolerance in 2002. The genetic basis was determined for salt tolerance among yield parameters. Tiller number was identified with the best selection efficiency among the parameters analyzed. Different genes may control grain yield under saline and non-saline conditions. Low genetic correlation between tiller number and panicle weight was identified. The low genetic correlation indicates the low compensatory relationship between these two yield parameters in rice plants under salt stress. It was concluded that salt tolerance in rice could be improved by selection of either tiller number of panicle weight. Technical Abstract: One of the major reasons for the limited success in salt tolerance breeding is the lack of reliable selection criteria in the screening for salt tolerance. This study was designed to determine the responses of yield parameters in rice plants to the selection for salt tolerance. F2 populations were developed from crosses between 'M-202' (salt-sensitive) and 'Agami' (moderately salt-tolerant) and grown in the greenhouse under salt stress (NaCl and CaCl2, 5:1 molar concentration). Selections were made in the F2 plants for the highest values of grain weight per plant, tillers per plant, and panicle weight under salt stress. The F3 populations of the selected F2 plants and unselected F2 plants, and their parental plants were evaluated for salt tolerance. Broad-sense heritability and realized heritability of grain eight per plant were determined to be 0.40-0.45 and 0.25, respectively. Higher broad-sense heritability (0.45 to 0.65) and realized heritability (0.42) of tillers per plant suggest this trait is genetically controlled. Moderately high realized heritability of tillers per plant indicates the effectiveness of early selection for salt tolerance if tiller number is used as selection criterion. Selection responses were dramatically different when both selection of F2 plants and evaluation of their F3 populations were made under non-saline condition or the F3 populations of the F2 plants selected under non-saline condition were evaluated for grain yield under saline condition. The direct effects of tiller number and panicle weight on grain yield under salt stress were identified as primary based on path-coefficient analysis. Low genetic correlation between tiller number and panicle weight was identified in F3 populations derived from the selected F2 plants. The low genetic correlation indicates the low compensatory relationship between these two yield parameters in equal spaced rice plants under salt stress. |
