The Analysis Of Heterosis And Correlation On Main Agronomic Traits And Chemical Qualities Of Flue-cured Tobacco

There is a strong contradiction between the yield and qualities of flue-cured tobacco, but the main goal of breeding of flue-cured tobacco is the balance in pursuit of yield and quality. The varieties rarely has a balance on yield with quality balance, in add to cultivars’ eing not diversifying, so the existing varieties can not meet the need of tobacco production. Through sexual hybridization, making full use of the existing germplasm resources, breed strong hybrid varieties from Hybrid Fl and separate the offspring to breed the excellent pure varieties. That’s always an important way for improving the breeding and production level. The performance of yield and quality traits in producing hybrids depends not only on their own, more important is the combining ability of yield and quality traits. In order to improve the breeding efficiency, accelerate the breeding process, reduce the chance, enhance predictability.the genetic study on the yield and quality characters of flue-cured tobacco, and the analysis on the combining ability,heterosis and correlation of main agronomic traits and chemical qualities,both can provide a scientific basis for tobacco parent breeding selection and progeny selection. There have ten Flue-cured tobacco varieties for the test materials in the study. Using diallel cross method Griffing Ⅱ. there prepared for45F1combination.The combining ability, heterosis and correlation of Flue-cured tobacco’s main traits were analyzed,which including agronomic traits(plant height, effective leaf number, stem girth and maximum leaf length, width, production of per unit area, rate of first class, pper-middle rate), and chemical quality traits (potassium, nicotine, reducible carbohydrate, total nitrogen content, chlorine content and the evaluation value,chemical components of coordination). The main results are as follows:(1)The agronomic traits and chemical qualities in combinations, reached significant difference, andthe variance of general combining ability (GCA) and specific combining ability (SCA) of the main characters reached a significant level. The additive effect and non-additive effect both have important influence on the expression of characters. The variance ratio of effective leaf number, leaf length, stem girth and potassium content in tobacco leaves GCA/SCA is larger than3when it’s in squaring period.while the narrow sense heritability is more than40%. Additive genetic effects dominate quite in these characters. Influence of parents was even larger on offspring, which can has genetic stability, so it’s suitable for selection in the early generations.The narrow sense heritability of these characteristics is less than25%, of which the additive genetic effect is smaller, while dominant effect and epistatic effect are larger. The leaf width, rate of first class, pper-middle rate, production of per unit area, nicotine, chlorine, total nitrogen content, nicotine included. The broad sense heritability of main traits were all above70%.To improve these traits, potential of genetic breeding is larger in some degree.(2)GCA of the same trait between different parents and different traits between the same parent are larger.Considering the main agronomic traits and chemical quality of flue-cured tobacco, general combining ability of the parental variety Qinyan96is more prominent, of which the overall effect is better. General combining ability in chemical coordination and main agronomic’s yield characters of the variety DianjiangYaZhong is more outstanding. General combining ability in chemical coordination and main agronomic traits whose except yield of the variety Honghuadajinyuan is more outstanding. All of them have the larger potential use in improvement of yield and quality collaborative traits, so they can be used as an ideal parent. The hybrid combination Dianjiang sprout×K358can be used as an ideal material in the research improving the coordination of chemical components, main economic traits and main agronomic traits.Heterosis except for in addition to rate of first class, pper-middle rate are obvious, and the general combining ability of parent has an outstanding performance.(3) The mid-parent heterosis between the agronomic traits and hemical quality of hybrid combination is widespread, but between the combinations significantly different.Heterosis rate of effective leaf number,rate of first class, pper-middle rate, potassium content, plant height, maximum leaf width is low. The mid-parent heterosis of the yield per unit area is obvious.(4)Chemical compatibility showed a highly significant positive correlation on reducible carbohydrate content, carbohydrate-nicotine ratio,rate of first class, pper-middle rate,while showed a highly significantly negative correlation on the content of total nitrogen, the ratio of nitrogen-nicotine.Among them, respectively, chemical compatibility related to the yield per unit area and reducible carbohydrate content significantly or in some extremely significant level.