盐碱洼地水稻直播栽培技术开发研究报告

STUDIES ON CROSS—BREEDING IN MILLET: Ⅱ. THE INHERITACE AND EFFICIENCY OF SELECTION FOR SOME TRAITS IN F2POPULATIONS

摘要:

本文分析了8个组合6个性状的F₂代遗传变异及各性状间的遗传相关、表型相关、遗传力和遗传进度。结果表明:F₂代的粒重、码数、千粒重、株高等性状分离均呈单峰曲线,近似于正态分布,虽然组合不同各性状的表现各异,但总体趋势一致。F₂群体普遍存在着超亲遗传现象。各性状遗传相关与表型相关的方向基本趋于一致,而且遗传相关系数的绝对值略高于表型相关的绝对值。通过株高、穗长、码数、粒数间接的提高选择产量的效率,通过码数、穗长达到粒多、大穗的目的。遗传力以千粒重最高,依次呈码数、粒数、粒重、株高、穗长。利用遗传力可确定谷子的育种规模。在5%的选择压力下,码数F₂群体的遗传获得量最大;码数、粒数对粒重的相关遗传增值最大,因此F₂群体应特别注重优良变异个体的选择,遗传力较高的千粒重可在F₂开始选择,粒数、注重后F₃、F₄代选拔,单株产量高代严格选择。

Abstract:

Genetical variability,heritability and genetic gain for 6 traits were analyzed and correlation coefficients between the traits were estimated from 8 crosses of millet. The results showed that the distributions of F₂s segregation for the traits, as such grain yield, numbers of spikes, 1000—kernel weight and plant height tended to be in normal curve with a peak, although varied with crosses. Transgressive phonmenon of the segregation occured widespreadly in F₂s. It was indicated that the absolute values for each of the genotypic correlation coefficients were higher than those for phenotypic ones, and both of the coefficients, generally, had the same direction. Selection efficiency for grain yield could be improved through indirectly selecting plant height,earhead length,and numbers of spikes and grains. An objective of large earhead could also be reached by improving numbers of spikes and earhead length. Heritability was highest for 1000—kernel weight,followed by numbers and of spikes grains, grain weight, plant height and earhead length. The highest genetic gain was observed for numbers of spikes in F₂ populations at 5% selection intensity and the correlated genetic gain of grain weight was highest in numbers of spikes and grains. It was concluded that considerable attention should be paid to single plant selection in F₂ populations,selection for 1000—kernel weight may start in F₂ due to its higher heritability,numbers of grains may selected in F₃ or F₄, and grain yield/plant in advanced generations.