Effects Of N, P Nutrition And Pruning On The Growth And Development Of Glycyrrhiza And Its Active Ingredients Content

Field experiments were conducted in Jingtai County and Yongdeng County of Gansu Province,from April 2007 to October 2008,to study the effects of pruning frequency and strength,levels of nitrogen and phosphate fertilizer on the growth and active ingredients content of Glycyrrhiza,an imporment traditional medicinal plant.The main results are as follows:1.In the second year of Glycyrrhiza's growth,different pruning had different effects on the growth of leaves,root of Glycyrrhiza and its active ingredients content.In the mid-period of slow growth phase,when cutting 1/4 height of the plant,weight of stem and leaves,Glycyrrhiza acid and liquiritin in roots were higher than that of CK,which increased by 34%,48%,16%and 65%respectively.When cutting 1/2 height of the plant at the same time,weight of stem and leaves,Glycyrrhiza acid and liquiritin in roots were higher than that of CK,which increased by 23%,30%,12%and 28%respectively.Above mentioned pruning didn't affect root length,root diameter and root weight.Pruning in the period of the slow growth could lead to over compensation on the growth of stem and leaves,and active ingredients content,and equal compensation on roots of Glycyrrhiza.2.Fertilization treatments affected the growth of leaves,root of Glycyrrhiza and its active ingredients content.Single application of nitrogen fertilizer could increase plant height and the number of leaves of Glycyrrhiza,and single application of a higher level of phosphate fertilizer could promote the growth of leaves and roots greatly.Single application of a higher level of phosphate fertilizer was beneficial to the occurrence of root nodules and increased root nodules weight.Lower level of nitrogen(75kgN/hm²),or combined with phosphate fertilizer,could increase the growth of Glycyrrhiza,as well as the accumulation of its Glycyrrhiza acid in roots.Combined application had better effects. With the increase of nitrogen dose,even combined with phosphate fertilization,the promoting role on the growth and dry matter accumulation were not obvious. Comprehensive analysis of the impact of different nitrogen and phosphate fertilizer application levels on the growth of leaves,roots of Glycyrrhiza and active ingredients content showed that the best amount of fertilization was 75 kgN/hm² and 240 kgP₂O₅/hm². 3.Cutting 1/2 height of three-year-old Glycyrrhiza at the middle of rapid growth phase,root length,root diameter,dry-root weight and the Glycyrrhiza acid content were examined.The plant without pruning was CK.Under the condition of without fertilizer, compared with CK,above mentioned index were decreased by 4.38%,13.78%,8.95%and 6.05%respectively.Therefore,lack of fertilizer,pruning had negative compensation. Compared with the corresponding fertilization treatments,except of single application of higher N or P,pruning in other fertilization treatments had equal compensation on roots growth and its Glycyrrhiza acid content.4.Among the pruning treatments,effects of pruning varied with the level of fertilization.Application of lower level of nitrogen or nitrogen combined with phosphate had overcompensation on main root length,root diameter and its dry matter accumulation after pruning,which increased by 14%～21%,25%～45%,14%～23%respectively. Pruning increased Glycyrrhiza acid content by 10%～23%under N application condition, and N fertilizer had overcompensation on pruned Glycyrrhiza.