Study On The Effect Of Growth On Loropetalum Chinense Var.rubrum Under Weak-Light Condition

Loropetalum chinense var.rubrum belongs to Loropetalum genus,Hamamelidaceae, which is rare bonsai plant and landscape gardening plant.To date,it hasn't studied systemically on the L.chinese var.rubrum shade-tolerance in domestic and abroad.This paper studied on the variation of shape and physiology characteristic under low light stress of the L.chinese var.rubrum,to explore the shading-tolerance limit of the L.chinense var.rubrum on the premise of keeping its ornamental value.The results showed:According to the light intensity reduced,the average length of fresh shoots increased first and then reduced.The average area of mature leaves reduced first and then increased. The stomata density of leaves and the specific leaf weight(SLW) dropped.The fresh leaf water content increased,the difference reached the extremely remarkable level,the difference between mature leaves was not remarkable.After the net photosynthetic rate(Pn) enhanced first reduced.Transpiration speed(Tr),stomata conductance(Cond) and intercellular CO₂ density(Ci) rised obviously.The chlorophyll a content,the chlorophyll b content presented the trend of increase,a/b reduced first and then increased;the content of kind of carrot element undulation was obviously,under the high light level,increased along with the stress time increased,under the low light level,raised first and then reduced along with the stress time increased.In the mature leaves the anthocyanin content was reduced with the stress time increased under illumination condition below 200μmolm^-2s^-1,in the fresh leaves the anthocyanin content changed a little.The conductivity of mature leaves increased, the conductivity of fresh leaves change was small.The SOD active of leaves elevated first and then dropped.The Malondialdehyde(MDA) content micro reduced first and then increased,change scope of fresh leaves was small when compared to mature.The proline (Pro) content of fresh leaves raised,the proline(Pro) content of mature leaves felled first and then raised.In the mature leaves the sugar content slightly raised first,latter reduced,and then raised,in the fresh leaves sugar content increased first and then reduced.According to the light intensity reduced,the average leaf area,proline content, intercellular CO₂ density(Ci) of mature leaves of Dayehong was bigger than Qiaoyehong.The conductivity change scope and the MDA change scope of Qiaoyehong were bigger than Dayehong;Dayehong had bigger ability of weak light toleration than Qiaoyehong.Under weak light condition,the stomata conductance,chlorophyll content,MDA content could respond the growth condition of fresh leaf;the conductivity,MDA,proline, anthocyanin,water content could respond the growth condition of the mature leaf.