Research On Heterosis Of New Lines Of The Flue-cured Tobacco With High-potassium

Heterosis can be found in most quantitative traits of the tobacco. Content of potassium is an important indicator of the quality of tobacco. In order to research the heterosis for potassium content, quality traits, agronomic traits and resistance to diseases, six new lines and eight common varieties of the flue-cured tobacco was selected as materials. Based on the conditions described in the test, the following results:Heterosis to potassium content of F1had different proforment in variable field stages. Heterosis that compared to parent preformed best in rosette stage, to1.49%,but bad in seeding stage and maturity, was-6.90%and-8.34%. Compared with the better parent, heterosis of F1in potassium content mainly was negative, in fast growing stage especially, average was-15.09%, and there is no one of combinations had significantly advantage, but17.65%and29.41%of combinations have significantly advantage in rosette stage and budding stage respectively. Compared with K326, heterosis of Fl was significantly, especially in seeding stage and maturity, average was35.34%and23.32%respectively, and all of combinations had significantly advantage.The heterosis was different in variable compositions and parts of plants, and preformed in upper leaf> bottom leaf> middle leaf,8.45%,7.59%and5.64%respectively. And compared with K326in upper leaf, bottom leaf and middle leaf was17.81%,4.06%and1.12%respectively. Compared to the better parent, F1had no significantly advantage in all leaves, average was-0.48%,-0.43%and0.05%in upper, middle and bottom leaf respectively.The GCA of different lines varied significantly. Variances due to SCA and GCA in K content of all leaves were (significantly) different. It indicated that that the character of K content of tobacco was mainly controlled by non-additive genes. GK2have greater GCA effect in K content of all leaves; GK7preformed good at GCA effect to K content in middle and bottom leaf, but badly in upper leaf. GK9preformed good in upper leaf, but badly in bottom leaf. SCA effect of MSChangbohuang×GK5, MSYunyan85×GK2, MSYunyan85×GK8and MSYunyan87×GK9preformed good in all leaves.Plant height, pitch, stem circumference and leaf width of F1had a significant advantage, to5.89%,21.31%,4.31%and4.29%respectively. While the leaf length and leaf number was mainly negative advantages, was-2.55%and-9.43%respectively. Heterosis of different agronomic traits was changed significantly in different periods, but changes occurred mainly at the4th to5th week after transplanted.As to quality traits, main chemical constituents of F1in different leaves were significantly different from parents and K326. Compared with average of parents, total sugar and reducing sugar of F1in upper leaves increased significantly with3.42%and5.74%respectively; Total nitrogen, protein, nicotine and chlorine content reduced significantly with-6.15%,-5.00%,-10.36%and-17.45%respectively; and potassium content increased with1.33%. Compared with the K326, sugar content of Fl was little; nitrogen compounds and potassium content increased obviously. Compared with the average of parents and K326, sugar substances and nitrogen compounds of F1increased in trend, potassium content had little changes, chlorine content decreased in middle leaf. Indicators in bottom leaf are closer to the average of parents, except the K/Cl increased with43.09%, that was higher than average; while compared with K326, Indicators increased significantly, except the chlorine content and the sugar/protein decreased.In the aspects of resistance, six new lines with high-K susceptible rate higher, with an average of41.69%, significantly higher than the control variety K326,27.50%, which GK7is relatively low,30.67%, but GK2is highest,57.50%. Hybrids of tobacco had heterosis to resistant to black shank and bacterial wilt disease, the average susceptibility rate of29.64%, lower than41.69%of the male parent, female parent,30.81%, but higher than K326,27.50%.MSYunyan85×GK2, MSYunyan87×GK2, MSYunyan87×GK7, MS101×GK8, MSK326×GK3and MSK326×GK9have good overall performance in the initial screening.