Effects Of Different Potassium Application Levels And Methods On The Growth And Quality Of Sun-cured Red Tobacco

Pot and field experiments were carried out to study the effects of different potassium application levels and methods on the growth and quality of sun-cured red tobacco with Xiao Huaqing variety in Xiangxi of Hunan province from 2003 to 2004.The results were as follows:1 Effects of different potassium application levels on physiological characteristics of Sun-cured red Tobacco leavesAt the rosette and vigorous growing stages, the activity of invertase was improved with increasing of potassium fertilizer application levels, which was the highest when K2O applied amounts were 375kg/hm2. The activity of invertase descended at the floral bud emergence and mature stages. The activity of amylase was the lowest among 40 days after transplanting, then reached the highest level at the 55th day after transplanting and had significant difference among treatments. Potassium fertilizer had no significant influence on the regulation of the endopeptidase activity, but it favored to the increasing of the soluble protein contents. With increasing of potassium application rates, NR activity reduced gradually, when potassium application rates increased more, NR activity decreased more. The potassium fertilizer could raise ATPase activity of tobacco root.There was close relationship between potassium and growth, development, aging of sun-cured red tobacco. With the advance of growing period, ABA contents in sun-cured red tobacco leaves increased. During the period of 75~90days after transplanting, ABA contents descended gradually with increasing of potassium application rates. Insignificant change was observed during the whole growth period. Potassium- applied could increase the IAA contents, but oversupplying potassium could inhibit the synthesis of IAA and reduced its content. Adding the application of potassium fertilization could promote the ability of chlorophyll's synthesis in the early growing stage; the photosynthetic rate and function of tobacco plant was improved. Fv / Fm and Fv /Fo could be regulated and controlled significantly.2 Effects of different potassium application levels on the growth of sun-cured red tobaccoDifferent potassium application levels had no obvious influence on botanical characteristics of sun-cured red tobacco. Appropriate potassium application rates could improve botanical characteristics to a certain extend. Improving potassium...