遮阴对红松苗木生长及光合生理的影响OA

[Objective]Broad leaved Korean pine forest,as a zonal top vegetation,can maintain ecological balance and other functions.Korean pine,as a constructive species,is very sensitive to the light environment in the process of regeneration.Therefore,study was carried out to explore the optimal light environment for the growth of Korean pine seedlings,to provide a theoretical basis for the construction and maintenance of natural and artificial broad-leaved Korean pine forests.[Methods]This study took the biennial seedlings of Pinus koraiensis in the nursery of Caohekou Experimental Forest Farm as the research object,different shading treatments(CK,and L1-L4,with light transmittance of 100%,76.4%,62.3%,39.8%,19.8%,respectively)were artificially constructed,and the growth and photosynthetic characteristics of Pinus koraiensis were measured,to investigate the effects of different shading environments on seedling growth and photosynthetic physiology,to screen the optimal light environment for seedling growth.[Results]From 2021 to 2024,under L4 treatment,the seedling height,ground diameter and annual increment of Korean pine seedlings were consistently significantly lower than those of other treatments.Seedlings under the L1 treatment had the highest survival rate(96.7%),the stem biomass and total biomass were significantly higher than those of L4 by 238.8%and 194.4%,respectively.The leaf biomass and root biomass of L2 were higher than those under the L4 treatment by 184.4%and 162%,respectively.The quality index of L1 was higher than that of CK and L4 by 126.4%and 134.2%,respectively.Under non-full sunlight treatment,the chlorophyll content of Korean pine needles increased with increasing shading intensity,and the chlorophyll a,chlorophyll b,and total chlorophyll content of L4 were at the highest level.In June,the starch content of L1 treatment was significantly higher than that of CK and L4 by 19.9%and 51.3%,respectively.In October,the soluble sugar content of L1 treatment was higher than that of other treatments(CK,L2-L4)by 11.0%,21.1%,14.0%,and 11.6%,respectively.The trend of soluble sugar content in needles under L1 and L2 treatments showed an"N"shape;both Fo and Fm decreased first and then increased with increasing shading intensity.During the phase I of the chlorophyll fast-phase fluorescence parameter curve,the Vt value under L1 treatment was higher than that of CK by 1.16%,and the maximum photochemical efficiency of PSII(FV/Fm)and the potential activity of PSII(Fv/F0)reached their maximum under weak shading conditions(L2).[Conclusion]Two-year-old Pinus koraiensis seedlings exhibit the best comprehensive performance under a light environment with a transmittance of 62.3%to 76.4%.Within this range,their growth conditions are optimal,with annual growth,biomass accumulation,photosynthetic product allocation,and photosynthetic organ function all in their best states.They are able to fully utilize light energy and allocate photosynthetic products reasonably during the growing season.In the process of Pinus koraiensis regeneration,measures such as regulating forest gaps or thinning can be taken to change the light environment and optimize seedling growth conditions.