Comparing The Potassium Nutrition Of Varieties Of Tobaccos

Low content of potassium in the tobacco is a key point which degrades the quality of tobacco in China and how to improve this feature is a hotspot in many research works. Comparison of K⁺ uptake efficiency of four typical tobacco genotypes is demonstrated in this paper by using a solution culture method. Our research puts emphasis on these facets: the relationship between K⁺ uptake and PH value, differences in K⁺ uptake kinetic parameters, potassium accumulate in tobacco and Physiological and morphological indices. The mechanism of K⁺ uptake efficiency difference between genotypes is discussed. Herein is the main results:1. In the solution culture experiment without potassium application(content of potassium is 300μmol·L^-1), four kinds of tobaccos were cultivated in a solution culture of Hoagland with K⁺ concentration 300μmol·L^-1 under the condition of greenhouse nutrient solution. K⁺ uptake kinetic parameters and the pH value were analyzed by using Ion Depletion Technique when tobaccos were at 9 leaves stage. Experiment shows that the changes on K⁺ concentration and pH value of Huanghua 93-1 are least while parameters of Yunyan 85 change most.2. Compared with a potassium-inefficient genotype tobacco, the root of a potassium-efficient one has a significantly higher value of "Imax" and "Km" while "Cmin" is lower and has a prominent difference. So K⁺ uptake kinetic parameters can indicate the different ability in potassium absorbing between genotypes, and Imax, Km, Cmin could be regarded as the peculiarity index used for potassium-efficiency genotype tobacco selection. The ability in potassium absorbing of Yunyan 85 is the strongest in four kinds of types in the experiment which brings Yunyan 85 is fitted with a relatively loose cultivate condition. Huanghua93-1 has relatively a worst K⁺ uptake ability. When cultivated without potassium application, K326 has a stronger appetency between root and K⁺ than Dafu, while in a high concentration condition, Dafu owns much predominance than K326. 3. Under different potassium applications, a potassium-efficient genotype tobacco has a robust roots. Many differences can be observed during the growth. Compared with Dafu and Huanghua93-1, Yunyan 85 and K326 have obvious advantage in infecting leaf potassium deficiency disease slower and having much longer life of leaves and having more individual weight in low potassium application . Photosynthesis of Yunyan 85 is the most prominent, it can self-feed through decreasing the transpiration; while photosynthesis of Huanghua93-1 is the most weak and which in Dafu is a little better than K326.4. The content of potassium in a potassium-efficiency genotype tobacco is much higher than that in a potassium-inefficiency genotype one in the solution of different concentrations. The sequence of the total potassium uptake content in different parts of tobacco is leaf >caudex>root.