Purpose To study the selection effects of environmental temperature change caused by altitude on F1 gamete genotype under the cytoplasmic background of indica and japonica rice and its effects on genetic selection of cold tolerance at booting stage in segregation population, providing reference for rice cold tolerant breeding.
Methods The correlation of biological characters were analyzed in F2 populations generated from reciprocal hybrids at three different altitudes planted at 2 200 m altitude. The material parents were Xiaomagu, japonica rice landrace that had strong cold tolerance, and Nan 34, an improved japonica variety that cytoplasm donated by indica rice. On this basis, regression analysis and path analysis were conducted on spikelet fertility, which was a main index of cold tolerance at booting stage.
Results The altitude of the F2 population had a significant effect on the correlation among the traits in the F2 population, and this effect was affected by the cytoplasmic background of indica and japonica. The number of filled grains and the total number of grains in all F2 populations had a significant contribution to spikelet fertility, among which the number of filled grains had a positive contribution and the contribution was the largest, and the total number of grains had a negative contribution. Factors such as plant height, panicle length and grain density also showed certain contribution values in different F2 populations.
Conclusion F2-generated altitude and cytoplasmic background have obviously effects on genetic selection of cold tolerance at booting stage of F2 population in rice. In rice cold tolerance breeding, parents with strong cold tolerance can be selected for hybridization. The F1 hybrids are planted under different environmental conditions with large altitude or temperature differences, and then the segregating populations are planted under low temperature conditions for screening.
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