Genetic Studies On Heterosis Of Economic Characters In Flue-cured Tobacco

The heterosis utility of flue-cured tobacco,introduced earlier in China,develop slowly and lag much behind America and Brazil.At present,the varieties of flue-cured tobacco hybrid never attains its rightful position in Chinese tobacco production.Therefore it is necessary to strengthen the studies on heterosis utility of flue-cured tobacco.In the experiment,12 hybrids crossed among 3 cytoplasmic male sterile lines,bred in Central-South Agricultural Experiment station,CNTC,and 4 varieties of flue-cured tobacco popularized in China were used to determine the heterosis and its genetic effect in economic.Results were as following:1.The heterosis for economic was found in most crosses,which indicated that improvement of economic traits by heterosis utility was possible.Perfect Crosses of MsYZ206-9×Yunyan87 and MsYZ216-Yunyan87 showed big potentiality in tobacco production.2.Flue-cured tobacco's economic characters were controlled by several genetic effects.Yield,top-class tobacco and high-class tobacco were mainly controlled by dominance effects,which had more potency on the utilization of heterosis.Average price,production value and class index were highly controlled by dominance effects and additive effects at the same time.Not only can economic characters' dominant effects' potency be exhumed with the utilization of hybrid superior,but also they can be accumulated and fixed by selection in routine cross-breeding.Dom.Evn.effects of economic characters showed significantly different at 0.05 or 0.01 levels,and the environments,the Mshybrids of flue-cured tobacco growing in,might have great influence on hybrids heterosis.In order to give a comprehensive evaluation on crosses and their value of utilization,it is necessary to make an on-the-spot investigation on the crosses under different envionment.