不同轮回选择改良轮次玉米群体选系的育种潜势

【目的】研究18个从不同轮回选择改良轮次玉米群体中选育自交系的育种潜势，为玉米群体的有效改良及育种利用提供理论依据。【方法】以2个群体3个不同轮次改良后代中选育的高代自交系为材料，通过农艺性状表型鉴定、配合力测定和SSR分子标记遗传多态性分析的方法，对这些群体高代选系的育种潜势进行研究。【结果】改良群体高代选系产量和主要构成性状及其GCA表现优于基础群体高代选系，但多数改良群体高代选系株高、穗位高及其GCA都较各自的基础群体高代选系有所增加。不同群体高代选系之间，表型及配合力差异较大，来自同一群体不同基本株的选系之间差异也较大。SSR分析结果表明，改良群体高代选系在自交代数少1代的情况下，其纯合的位点比例与基础群体高代选系相当，与基础群体高代选系相比，改良群体高代选系间遗传差异虽有减小的趋势，但仍有较大的遗传差异。改良群体高代选系P4MSC2-1、P4MSC2-2、P5MSC2-2和P5MSC2-3以及基础群体高代选系P5C0-3，自身产量和主要性状及其GCA表现较好，与测验种所配组合产量较高，有较大的育种利用价值。【结论】群体高代选系的表型和配合力差异来源于不同群体及基本株的差异，从经过改良的群体中选育出的自交系表现更好，用改良群体选系纯合速度较快。

Breeding Potentiality of the Inbred Lines Derived From the Maize Populations Developed by Different Cycles of Recurrent Selection

【Objective】The objective of the present study is to estimate the breeding potentiality of 18 lines derived from six improved populations, thus to provide a scientific basis for generating strategies of deriving lines from an improved population.【Method】A total of 18 inbred lines derived from 6 maize populations developed by different cycles of recurrent selection were used as experiment materials. The phenotypes of the 18 lines per se were analyzed, and the combing ability of major traits was tested according to an incomplete diallel model, the genetic diversity of the lines was analyzed by SSR markers. 【Result】 The results showed that the inbred lines derived from different populations, and the inbred lines derived from different basic individuals in a same population varied in the phenotype and combing ability. The inbred lines P4MSC2-1, P4MSC2-2, P5MSC2-2 and P5MSC2-3 derived from the improved population were superior in yield, yield component and their general combing ability (GCA), the hybrids between these lines and the testers were high in yield. In summary, most of the inbred lines derived from the improved population were better than the inbred lines derived from the base population in yield, yield component and their GCA. However, the inbred lines derived from the improved population were taller in plant height and ear height. The number and percentage of homozygote of the lines derived from the improved populations were roughly equivalent to that of the lines derived from the basic populations with one inbred generation less. The genetic diversity of the lines derived from the improved population showed a decrease trend, but the genetic diversity was still rich relatively. 【Conclusion】All the results indicated that the inbred lines derived from an improved population were more superior, and when the individuals of the improved populations were inbred to develop lines, it became homozygous faster than the basic populations.