Effects Of Rocky Desertification On The Growth And Main Medicinal Components Of Uncaria Rhynchophylla In Karst Plateau

In this paper,the three-year-old Uncaria rhynchophylla was used as the experimental material,we compared the indexes related to growth and development of planting materials in the rocky of the karst plateau and non rocky environments to reveal the effects of rocky desertification on U.rhynchophylla growth and its main medicinal components.The main results were as follows:1.To clarify the effects of rocky desertification on the growth of U.rhynchophylla.Comparing rocky desertification area of karst plateau with four non rocky cultivation areas,the phenological period of U.rhynchophylla in the rocky desertification area showed as follows:bud expansion period,bud opening period and leaf unfolding period were advanced,new shoot growth period,hook growth period and peak period were delayed,etc.;the morphological indexes of U.rhynchophylla were as follows:growth was slow,plant height was reduced,stem diameter was shortened,number of leaves,area of leaves,number of primary branches,length of branches,spacing of lateral branches and number of hooks were significantly reduced.In a word,in the rocky desertification area of karst plateau,the plant of U.rhynchophylla was short and compact,and it could resist the adversity through the adaptive change of morphology.2.To clarify the physiological response of U.rhynchophylla to rocky desertification in karst plateau.Comparing rocky desertification area of karst plateau with four non rocky cultivation areas,the photosynthetic characteristics of U.rhynchophylla in the rocky desertification area showed as follows:Gs in leaves decreased,Tr decreased,WUE increased,CI in leaves increased to a great extent,and high concentration of CO₂promoted the increase of Pn;the physiological indexes of resistance in leaves of U.rhynchophylla showed as follows:membrane lipid peroxidation increased,MDA content increased,SP,SS and Pro content of osmotic substances increased,and the increase was SP>Pro>SS,CAT,POD and SOD activities of antioxidant enzymes were lower,the scavenging capacity of active oxygen was weaker,the content of chlorophyll a and chlorophyll b decreased,but the content of carotenoids increased.In a word,in rocky desertification area of karst plateau,U.rhynchophylla could adapt to the adversity by reducing stomatal conductance,reducing water loss,increasing osmoregulation substance content and improving water holding capacity.In addition,high concentration of intercellular CO₂could promote photosynthetic rate and other physiological responses.3.To clarify the effects of rocky desertification on the accumulation of effective components in U.rhynchophyll.Comparing rocky desertification area of karst plateau with four non rocky cultivation areas,the contents of RIN and IRN in the four parts of U.rhynchophylla in the rocky desertification area showed as follows:in the vigorous growth period,the contents of RIN and IRN in the main stem increased,in the harvesting period,in the three parts of leaves,stems with hooks and lateral branches without hooks increased,and the effect of promoting the contents of IRN was stronger.In a word,rock desertification in karst plateau could promote the accumulation of RIN and IRN in U.rhynchophylla.4.To clarify the effects of different levels of rocky desertification on the growth,physiology and main medicinal components of U.rhynchophylla.The higher level of rocky desertification,the worse growth of U.rhynchophylla and the formation of hook.Meanwhile the plant height,stem diameter and branch number changed obviously with the increase of rocky desertification level;With the increase of rocky desertification level,the MDA content in leaves increased gradually,SS content increased first and then decreased,SP content increased gradually,CAT activity decreased first and then increased,Pod and SOD activity increased first and then decreased;chlorophyll a,chlorophyll b and carotenoid content all of them increased first and then decreased;Moderate rocky desertification had the strongest effect on the accumulation of RIN and IRN in U.rhynchophylla.