Effects of soil acidity adjnstment on root growth and chemical compositions of the cured leaves in flue-cured tobacco

The results from pot experiments show that when soil pH value is adjusted to 5.5～6.6 from 5.0，root growth is improved，and the absorption of N，P，K is accelerated，When soil pH value> 7.0，root growth is inhibited．With the increase of the soil pH value，the contents of total nitrogen，nicotine and Ca in cured leaves increase，the contents of total sugar，Mg，Mn，Zn，Cu and B decrease，the content of potassium is nearly not varied．When soil pH value is raised to 5．5～ 6．6 by lime application，the contents of various chemical compositions are rational in cured leaves，the quality of leave is better．It is better for the acid soil to apply lime together with an appropriate amount of magnesium and micro-elements.