| Loquat(Eriobotrya japonica Lindl.)is the special fruit tree in Southern China.The photosynthesis is very important for the growth,flowering,yield and quality of fruiting of fruit trees.We choose loquat trees at their vigorous growth stage as materials to study the effect of shading and boostering light on the photosynthesis,physiology and biochemistry,expression level of photosynthetic genes during fruit development,and fruit quality of loquat during the period of fruits development,and the main results are as follows:1.During the period of fruit development,shading by bilayer-net and monolayer-net decreased value of P_n,G_s,T_r and WUE,but C_i increased.On the whole,the greater the intensity of shading,the greater the impact is.There is no significant effect on the photosynthesis of booster-light group.2.The lasting shading stress has great influence on the content of mineral elements in loquat leaves,performing as improving content of N,Ca,K,Mg and Cu,increased firstly and then decreased the content of Fe,having little effect on the content of P;the effect of boostering light on P content in the leaves are obscure,perform as decreasing the content of N,K,Mg and Fe,increasing the Mn content,but having no siginificant effect on content of P,Ca and Zn.The lasting shading stress obviously increased 24.97%of the content of ursolic acid in loquat leaves,decreased the content of corosolic,but both shading and boostering light treatments had no siginificant effect on the content of maslinic acid in leaves.3.Under lasting shading stress,the defoliation rate of loquat tree is fairly high,and the accumulation of dry matter in leaves decreased greatly,especially the defoliation rate of bilayer-net group reached 97.275%,while the effect of booster-light treatement is not significant on the accumulation of dry matter in leaves and the defoliation rate.4.Lasting shading stress of monolayer-nets increases the expression level of psaB and psbA in the leaves,inhibits the expression of psaA and psb D,and expression level of psbC was fairly low,and due to the high-intensity of shading stress,the expression level of psaA,psbC and psaA of bilayer-net group are closed to 0,decreased the expression leavel of psaB and psbA in leaves;and booster-light treatment decreased the expression level of psaA and psbC,promote the expression of psbD,but has little effect on the expression level of psaB and psbA.5.Lasting shading stress during the period of fruit development greatly decreased the single loquat fruit weight,fruit size and soluble solids content,while booster-light treatment has little effect on the fruit quality. |
