Genetic Analysis For Several Aromatic Substance Contents Of Cucumber (Cucumis Sativus L.) Fruit

Cucumber (Cucumis sativus L.) is one of Cucubitaceae, which collectively belongs to a group of vegetables known as cucurbits and stands the fourth place followed by tomato, Chinese cabbage and onion. Cumuber was favorited all over the word. It has some characteristics, such as high yield, nutrient-rich and cost-effective. It is not only as raw, cooked, pickled vegetables, but also as fresh fruit. Unique flavor is one of the important characteristics of cucumber, on the one hand, it depends on the flavor quality of cucumber sugar, Vc, organic acids, tannins and so on, on the other hand, it is closely related to the aromatic substances.Enhancing flavor of cucumber is one of important goals in cucumber breeding and production. The flavor is one of quality characters which is not easy to be studied. Because of restrictions on the means of test analysis, its inheritance is not clearly. Cucumber aromatic substance content is an important factor that affects the quality of cucumber flavor. At present, the research of aromatic substances limited to determination, material composition, the cultivation conditions, and so on. In my study, Genetic analysis for the main aroma substances of cucumber fruits has been carried out with the method of diallel analysis and quantitive traits heredity mode by using the commix model of main gene and multiple genes. Exploring the genetic mechanism of aromatic substances, it will be provide the important informations for quality breeding of cucumber.Analysis of cluster and principal component on six quality traits was carried out with 40 varieties of the cucumber.Six varieties were choosed as the cross parents, we got 15 hybrid combinations with the method of Griffing 2. Six parents and fifteen F1 hybrids were used for the analysis of the genetics of aromatic substances in cucumber by genetic models which including additive-dominance effects and their interaction effects with environments. Genetic analysis for the content of 2E, 6Z-nondienal in cucumber fruit has been carried out with the method of quantitive traits heredity mode by using of the mixed major gene and polygene inheritance model with EP326(the higher content of 2E, 6Z-nondienal) and DE843(the lower content of 2E, 6Z-nondienal) as the parents. The main results are as follows.1 Analysis of cluster and main compound on six quality traits was carried out with 40 varieties of the cucumber. The results showed that 40 varieties were divided into six principal components, and of which, the contribution rate of yield, flavor and diameter of fruit is 88.61%. Based on the cluster analysis, at the genetic distance of 0.18, the 40 varieites could be divided into two types, the content of 2E, 6Z-nondienal is low in the first category and the second category is high. It could be divided into four categories at the genetic distance of 0.10. The 2E-nonenal contents of cucumber in the first category is lower, the weight is lighter and the figure is smaller; cucumber is more weighty and longer in the second category; the third category has three varieites, in which Carmen and Cixi are small figure; the 2E-nonenal contents of cucumber in the fourth category is higher, length and weight are medium.2 Six parents (EP326, Xiu yan, Ri jiecheng, Xian feng, DE843 and Burpee) and fifteen F1 hybrids under two environments were used for the analysis of the genetics of aromatic substances of cucumber by genetic models including additive-dominance effects and their interaction effects with environments. The results showed that 2E-nonenal, octanol and 2E, 6Z-nondienal of cucumber were controlled by both additive and dominant effects and, nonanal and 6Z-nonenal were mainly controlled by the additive effect. The additive×environment interaction effects of 2E, 6Z-nondienal were best significant. Both general heritability of narrow sense and general heritability of broad sense of five aromatic substances were significant at 1% level probability,it indicated that the selection might be more effective in early generations. The extremely significant genetic correlation existed among the five aromatic substances in cucumber. And predicted F1 heterosis genetic performance of the five kinds of aromatic substances under two environments in part of the combinations.3 Six generations of P1, P2, F1, BC1, BC2 and F2 from the cross of cucumber cultivar EP326 and DE843 were employed to analyze the genetic effects of the characteristic aromatic substance 2E, 6Z-nondienal by using of the mixed major gene and polygene inheritance model B-1model,the additive-dominance-epistasis genetic model, which was controlled by two pairs of major genes, was the best one for genetic analysis of the characteristic aromatic substance 2E, 6Z-nondienal in cucumber. The genetics of the characteristic aromatic substance 2E, 6Z-nondienal in cucumber could be explained mainly by additive effects. Therefore, the strategy of cross breeding could be effective for increasing the characteristic aromatic substance 2E, 6Z-nondienal content of cucumber.