Studies On The Differences And Physiological Mechanisms In Potassium Absorption Of Different Tobacco Genotypes

The potassium content level of tobacco leaf has a direct impact on the quality of tobacco leaf. In recent decades, we have done large numbers of work on increasing the potassium content level of tobacco leaf, but it is hard to increase the potassium content level of tobacco leaf depend on increasing potash fertilizer application or improving the fertilization skills. The potassium resource of our country is so scarce that most of the potash fertilizer depends on importation, therefore, initiating the study on the difference and mechanism in potassium absorption of tobacco genotypes, not only can enrich the plant nutrition theory of our country, but also have a great application value on increasing the quality of high grade tobacco leaf in our country. Using hydroponic condition, we compared the difference of root system morphology, physiologic characteristic among four flue-cured tobacco varieties Nongda 202, RG17, NC89 and Jingyehuang. The results are as follows:1. These four cultivates had significant difference in root system and physiologic characteristic. Nongda 202 and RG17, containing higher potassium, had remarkably bigger root system volume, stronger root restore vigor and total vigor, larger root system active absorption surface than the cultivates NC89 and Jingyehuang.2. During the developmental period, Nongda 202 and RG17 with higher potassium possessed a lower ability of proton secretion when they were treated using lower concentration potassium than the other two cultivates, while being treated using higher concentration potassium both of them had a higher ability. During the vigorous growing stage, Nongda 202 and RG17 secreted more protons when the concentration of potassium was much higher in the environment.3. Along with the development of tobacco, their amount of exchangeable cations were increasing. The CEC and the capacity of potassium had a significant positive correlation. The absorption of potassium in the root was affected by the CEC. When the potassium concentration was higher in the culture, the root CECs of Nongda 202 and RG17 were higher than of the other two cultivates, while in the lower potassium culture, the difference of root CEC among these four cultivates was not significant.4. Along with the development of tobacco, the amount of soluble proteins and the ATPase changed significantly among these four cultivates. The activity of ATPase decreased significantly, while the amount of soluble proteins remarkably increased. Nongda 202 and RG17 had a higher amount of soluble proteins and ATPase than Jingyehuang and NC89. Cultivates with higher ATPase activity possessed a much more potassium and a higher accumulation capacity.