Study On Early Evaluation Of Anti-abiotic In Different Flue-cured Tobacco Varieties

Variety is the foundation of tobacco production, which is the foundation of tobacco industry development. National Tobacco Monopoly Bureau paid great attention to tobacco breeding in order to meet the demands of Chinese-style cigarette and sustainable development of tobacco production. Nowadays, great progress has been made in the tobacco breeding, but there is still a wide gap with the sustainable development. There is a lack of comprehensive research on inheritance of several important characters (anti-adversity and quality). The seed characteristics and physiology of anti-abiotic stress (drought resistance and cold resistance) were studied through the methods of plate culture technique and regular technology with flue-cured tobacco varieties approved by the national committee as materials. The main conclusions are as follows:1. Based on the results of wet-hot sterilization, it was proved to be the optimal method to sterilize when seeds to be soaked firstly in the aseptic water at 50℃for 10 min, secondly to be immersion in 70% ethanol for 30 s and finally to be soaked in 10% sodium hypochlorite. The method is effective to reduce the ratio of contamination and to improve the germination. The plate culture technique was convenient to get aseptic seedling without restricting of time and the environment was easy to control. So it is not only save the manpower and material resource, but also to keep the integrated roots which are feasible to conduct botanical research. Besides, it is also suitable to be applied to research of early stage screening and comprehensive evaluation on disease resistance, drought resistance and cold resistance of large number of varieties.2. Low potassium stress restrained the root growth, decreased root/shoot ratio and total length of roots, and inhibited the occurrence of lateral root. But no significant influence was found on root diameter. Root hair number was increased and only occurred near by the root tip. The genotypic variation in response to low-potassium stress was also observed. Compared with other varieties, NC82 was affected least by low potassium stress. The results also showed that biomass of flue-cured tobacco seedling with this agar culture system can serve as an earlier selection criterion for tolerance to low soil potassium content, by which large scale screening of flue-cured tobacco germplasm can be carried out rapidly and efficiently.3. low potassium stress restrained the root growth, decreased root/shoot ratio and total length of roots, and inhibited the occurrence of lateral root. But no significant influence was found on root diameter. Root hair number was increased and only occurred near by the root tip. The genotypic variation in response to low-potassium stress was also observed. Compared with other varieties, NC82 was affected least by low potassium stress. The results also showed that biomass of flue-cured tobacco seedling with this agar culture system can serve as an earlier selection criterion for tolerance to low soil potassium content, by which large scale screening of flue-cured tobacco germplasm can be carried out rapidly and efficiently.4. Plant fresh weight, taproot length, total length of lateral root, root system vigor, chlorophyll content and protoplasmic membrane penetrable of a tobacco variety under normal conditions differed remarkably from those of the same variety under osmotic stress treatment. Fresh weight, total length of lateral root and permeability of plasma membrane were the sensitive indexes of drought resistance. In addition, the study indicated that drought resistance in different tobacco varieties was highly variable, and they were in order of NC82>RG11>Hongda> G28>K326. Meanwhile, this plate culture can be applied to screening and evaluation on drought resistance of tobacco germplasm resource.5. The chilling tolerance and its related physiological indexes of several flue-cured tobacco varieties were investigated at low temperature (8℃and 5℃) stress. The results showed that Hongda had the best chilling tolerance, followed by NC82 and RG11, while K326 and V2 had the least chilling tolerance. The analysis of all correlation indexes made it clear that chilling injury indexes had highly significant correlation with the MDA content, the root activity, the chlorophyll content and the cell membrane permeability. These physiological indexes were sensitive to the change of low temperature. They were suitable parameters for evaluating chilling tolerance.