Breeding Potential Of Six Domestic Flue-cured Tobacco Germplasm Resources

Cultivated varieties of flue-cured tobacco production in China, although the quality is good, there is serious phenomenon of varieties simplification. Narrow genetic basis of tobacco germplasm resources has become one of the important factors that limit domestic tobacco production. In order to explore the breeding potential of domestic tobacco materials, and then create new germplasm and cultivate better hybrid tobacco, it is an important way to broade the n genetic basis of tobacco germplasm resources and breed new varieties of tobacco. Use SSR molecular marker in this test to analysis genetic differences of 13 flue-cured tobacco material, and clustering analysis based on molecular genetic distance of the selected materials genome DNA; six domestic materials including Yunyan 2, Honghuadajinyuan, Liuyejian 2017, Xiaohuangjin, E'shan tobacco, and Yunyan 87 compared with seven foreign materials including Dixie Bright 101, K394, Oxford 26, Ti448A, Hicks 55, Special 55, and NC2326, according to the NCI design, which is also called nested design, genetic analysis and multiple comparison of the main agronomic traits and the main chemical compositions were studied. The results of the study are as follows:1. Major growth periods and the main botany properties compared between 23 hybridized combinations and control Yunyan 87, all the hybrid combinations using Yunyan 2 and E'shan tobacco as male parent were all one week late to mature relative to the control, and their early maturities are good; in the field, the offspring using Yunyan 2 and Honghuadajinyuan as male parent presented better.2. The results of SSR molecular markers showed in 13 parents, the average genetic distance was 0.202, of which the average genetic distance of domestic parents was 0.207, the average genetic distance of foreign parents between was 0.203, and the average genetic distance between domestic parents and foreign parent was 0.201. Yang Benchao et al.[64] using ISSR analysis for 24 flue-cured tobacco materials obtained tobacco genetic distance in the distance of 0.15-0.34, and the average genetic distance was 0.24, which showed the low flue-cured tobacco germplasm genetic diversity. Clustering analysis:six domestic germplasm resources in accordance with the geographical distribution were divided into four subclasses, which indicated a certain value of hybridization and breeding potential between tobacco germplasm resources in different regions.3. Variance analysis for the major agronomic traits and the main chemical components of 23 materials, the results showed that only the estimated average of middle effective leaf numbers has reached the significant level of 10 agronomic traits in the tested six germplasm resources; effective leaf number, the lower effective leaf number, middle effective leaf number, the upper leaf number, pitch, stem thickness, plant height, waist leaf area and parietal leaf area reached extremely significant level, but the difference of foot leaf area was not significant; 10 agronomic traits of genotype variance in 23 hybrid combinations reached the extremely significant difference, which explained effective leaf number, the lower effective leaf number, middle effective leaf number, the upper effective leaf number, pitch, stem thickness, plant height, foot leaf area, waist leaf area and parietal leaf area of the ten traits in all combinations had real genetic differences, and also these parents have larger breeding value on these traits. In 23 hybrid combinations, in the middle leaves, total sugar, reducing sugar and chlorine reached significant difference, but no significant difference in nicotine, potassium, total nitrogen; in the upper leaves, total sugar, nicotine, reducing sugar, chlorine and total nitrogen reached extremely significant difference, but no significant difference in potassium. In the middle leaves of male parent, reducing sugar reached extremely significant difference, but total sugar, nicotine, chloride and potassium were no significant difference; in the upper leaves of male parent, total sugar and reducing sugar reached significant difference, and total nitrogen reached extremely significant difference. In the middle leaves of female parent, total sugar, reducing sugar and chlorine reached extremely significant difference, but nicotine, potassium and total nitrogen were no significant difference; in the upper leaves of female parent, total nitrogen reached significant difference, and nicotine and chlorine reached extremely significant difference.4. Multiple comparisons of the main chemical compositions estimated average showed that the reducing sugar of middle leaves reached extremely significant difference, but total sugar, nicotine, chloride, potassium and total nitrogen were no significant difference; total sugar and reducing sugar of the upper leaves reached significant difference, and total nitrogen reached extremely significant difference. Estimated average of total sugar, reducing sugar and chlorine in the middle leaves reached extremely significant difference, but no significant difference in nicotine, potassium and total nitrogen; estimated average of total nitrogen in the upper leaves reached significant difference, and nicotine and chloride reached extremely significant difference. In the same female parent, the multiple comparisons between different male parents hybrid combinations showed that the offspring using Yunyan 2 as male parent, in the middle leaves, total sugar, total nitrogen, potassium, chloride and nitrogen these five indicators presented better, and reducing sugar and potassium of the upper leaves were basically in the range of good flue-cured tobacco quality content. Total sugar content, nicotine content and total nitrogen content of the middle leaves, and nicotine content, chlorine content and total nitrogen content of the upper leaves had a certain significant difference. The offspring using Honghuadajinyuan as male parent, reducing sugar and chloride of the middle leaves were basically in the range of good flue-cured tobacco quality content, and total sugar, nicotine and reducing sugar had a certain significant difference. The offspring using Liuyejian 2017 as male parent, reducing sugar of the middle leaves and the upper leaves, and total nitrogen and potassium content were basically in the range of good flue-cured tobacco quality content. However, sugar/nicotine ratio, sugar/nitrogen ratio and chloride/potassium ratio presented good only in few hybrid combinations. Total sugar, reducing sugar, chloride, potassium and nitrogen had a certain genetic difference. The hybrid combinations using Xiaohuangjin as female parent, total sugar and nicotine of the middle leaves had a certain significant difference, and total sugar, nicotine, reducing sugar, chloride and total nitrogen of the upper leaves had a certain significant difference. The hybrid combinations using E'shan tobacco as female parent, chloride of the upper leaves had a certain significant difference. The hybrid combinations using Yunyan 87 as female parent, chloride of the upper leaves had a certain significant difference.