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以236份云南地方粳稻核心种质和云南主栽粳稻Oryza satica品种合系35配制的杂种F5、BC1F4、BC2F3和BC3F2为材料,在昆明自然低温平均17.8℃(冷害)条件下,对亲本及其后代进行孕穗期耐冷性研究。结果表明:①亲本耐冷性状间的相关性明显高于其杂种后代,不同世代间总体趋势为随着回交世代增加其性状间相关性减弱。在亲本及其杂种后代间耐冷指标性状穗颈长、穗下节长、每穗实粒数、每穗秕粒数与结实率均呈较高的(≥0.370)极显著(n=236,R0.01=0.181)相关。②株高、穗颈长、穗下节长等耐冷性状在亲本强弱耐冷系统群间的差异明显,表现为亲本耐冷性强的材料秆和穗较长、穗粒数较多,同一性状变异程度减小。但随着回交代数的增加,这些性状的平均值逐渐趋同于轮回亲本,差异减小。③穗颈长、穗下节长、每穗实粒数、每穗秕粒数与结实率在5个稻作区间的变化规律呈现一致性,亲本和F5的差异较大,而BC1F4、BC2F3和BC3F2的差异较小,且趋同于轮回亲本。通过连续回交,在BC3F1即可获得耐冷性状表现良好的材料。
The hybrids F5, BC1F4, BC2F3 and BC3F2 were prepared from 236 core japonica rice varieties from Yunnan and Oryza satica cultivars from Yunnan, respectively. Under the condition of average low temperature of 17.8 ℃ (cold damage) in Kunming, Offspring bumper cold tolerance study. The results showed that: (1) The correlations between cold tolerance traits of parents were significantly higher than those of their hybrid offspring. The overall trend between generations was that the correlation between the traits was weakened with the increase of backcross generation. Cold tolerant traits such as panicle neck length, ear length, ear number per panicle, grain number per panicle and seed setting rate were all significantly higher (≥0.370) (n = 236, R0 .01 = 0.181). ② The cold tolerance traits such as plant height, panicle neck length, panicle length and ear length were significantly different among the cold-resistant and cold-tolerant parental systems. The results showed that the parental cold-tolerant material had longer stalks and spikes, Reduced. However, with the increase of backcrossed algebra, the average of these traits gradually converged with the recurrent parent, the difference decreased. (3) The variation law of panicle neck length, ear length, spikelets per panicle, grain number per spike and seed setting rate in five rice cultivars showed the same pattern of variation, while the differences between BC1F4, BC2F3 and BC3F2 is less divergent and converges with the recurrent parent. By continuous backcrossing, a material that performs well in cold tolerance can be obtained at BC3F1.