外源补光对桐花树光合作用特性及光合固碳释氧能力的影响OA

This study aims to explore the regulatory mechanism of artificial exogenous supplementary lighting technology on the photosynthetic characteristics and carbon sink function of Aegiceras corniculatum,address the problem of mangrove pho-tosynthetic obstruction caused by trestle shading during the construction of the Guangxi Longmen Bridge,and evaluate the ecological restoration effect of supplementary lighting measures under an engineering shading environment.A trestle shading model was constructed,and gradient supplementary lighting experiments were set up(0,220,275,330 μmol·m-2·s-1).A Li-6800 portable photosynthesis system and a TOP-1300 canopy analyzer were used to synchronously determine the diurnal photosynthetic dynamic parameters and leaf area index(LAI),and the differential characteristics of plant photosynthetic car-bon assimilation and oxygen release capacity under different supplementary lighting intensities were systematically analyzed.The results showed that(1)supplementary lighting treatment increased the net photosynthetic rate by improving the light in-tensity in the shaded environment,and the diurnal variation in the net photosynthetic rate(Pn)of A.corniculatum showed a bimodal curve(peaks at 10:00 and 14:00);(2)the carbon fixation and oxygen release per unit leaf area and per unit land area increased with the increasing of supplementary lighting intensity;when the supplementary lighting height was≥4 m,the photosynthetic indicators under medium and high supplementary lighting intensities(≥275 μmol·m-2·s-1)were close to those in the natural light environment(p>0.05);when the supplementary lighting height was<4 m,all photosynthetic indicators were significantly different from those in the natural light environment(p<0.05);and(3)correlation analysis showed that transpiration rate(Tr)and photosynthetically active radiation(PAR)were the main factors affecting carbon fixation and oxy-gen release.When the shading height is above 4 m,artificial supplementary lighting can effectively compensate for the light energy deficit caused by engineering shading,and it is recommended to adopt a supplementary lighting intensity of 275～330 μmol·m-2·s-1 to maintain the carbon fixation function of mangroves.This study can provide a quantitative reference for man-grove protection and restoration.