分裂交配对棉花育种群体的改良效应研究

Effects of Disruptive Selection and Mating on Improvement of Upland Cotton

从陆地棉育种材料中选择４个组合进行分裂交配。每个组合分别按开花早晚、纤维强度和纤维长度３个指标选择极端类型并杂交，经２轮分裂交配后每个组合产生７个群体。１９９５年对２８个群体进行随机区组比较试验。结果表明，４个组合的平均小区皮棉产量没有显著差异，而不同组合的纤维品质显著不同。１轮长×短、２轮长×短和２轮强×弱的交配方式产量明显高于基础群体和１轮早×晚群体。不同交配方式纤维品质不存在显著差异。分裂交配导致群体内植株若干性状变异程度增加，但降低另一些性状的变异。分裂交配对性状间相关系数变化的影响同样因组合和群体而异。４个基础群体均表现正相关的性状有单株皮棉与麦克隆值、整齐度与纤维长度、整齐度与麦克隆值及纤维强度与麦克隆值；均表现负相关的性状是纤维长度与整齐度。这些相关性不易通过分裂交配改变。

Disruptive selection and mating were carried out in four cross combinations from our cotton breeding program. In each cross combination, the earliest and latest types, the longest and shortest fiber types, and the strongest and weakest fiber types were selected and crosses were made for early × late, long × short, and strong × weak. Seven populations were produced from each cross combination after two cycles of disruptive selection and mating so that the author had a total of 28 populations. These populations were then compared with one another for their lint yield and fiber properties using a completely randomized block design. There was significant difference for fiber traits, but no significant difference existed for lint yield among cross combinations. One cycle of long × short, two cycles of long ×short, and two cycles of strong × weak populations yielded more than base and one cycle of early × late populations, however, base populations and disruptive mating populations did not significantly differ in fiber properties. Disruptive mating may increase variation of some traits within populations but reduce variation of other traits within the same populations, lacking certain trend. Correlation coefficients (r value) varied in different traits of different cross combinations and different treatments(base and/or disruptive mating populations). Positive correlations were found in lint/plant and micronaire, uniformity and length, uniformity and micronaire, and strength and micronaire in all four base populations. These base populations had negative correlation in length and uniformity. The positive or negative correlations described above cannot be changed dramatically by different disruptive mating methods.