Relationship Between The Photosynthetic Rate Of Salix Psammophila And Chlorophyll Fluorescence Parameters In Mu Us Sandy Land

In order to explore the relationship between photosynthetic rate and chlorophyll fluorescence parameters of Salix psammophila plants in the Mu Us Sandy Land.The net photosynthetic rate and chlorophyll fluorescence parameters of Salix psammophila were measured over growing season in 2019.We examined the effects of environmental factors?such as temperature,humidity,light intensity,etc.?on net photosynthetic rate,and the relationship between the photosynthetic rate of Salix psammophila and chlorophyll fluorescence parameters,it is of great significance to study the photosynthesis ability of plants in arid and semi-arid areas,and to provide a basis for the prediction of photosynthetic rate of plants and aimed to create a fluorescence parameter-based model of photosynthesis prediction.The main results are as follows:?1?The net photosynthetic rate increased with the increase of relative air humidity when relative humidity was in the range of 20%-80%,showing a logarithmic function.Photosynthesis-temperature curve showed a parabolic function,reaching the maximum when the leaf temperature was 28?,and the optimal temperature for photosynthetic was between 25-30?.Tthe maximum net photosynthetic rate of12.4?mol?m^-2?s^-1and the optimal light intensity of about 1144?mol?m^-2?s^-1.CO₂also affected the net photosynthetic rate of Salix psammophila,The photosynthetic rate peaked when CO₂concentration reached 1126.3?mol?mol^-1.?2?Chlorophyll content?SPAD?was in the range of 35-60 SPAD,the fluorescence parameters of Salix psammophila showing a single-peak curve throughout the growing season.The daily average value of each fluorescence parameter during the full leaf stage was relatively large.The chlorophyll content?SPAD value?of Salix psammophila had a certain correlation with the growing season changes of fluorescence parameters,but there was no significant correlation between them.?3?Net photosynthetic rate?P_n?was positively correlated with heat dissipation rate?K_v?and the non-photochemical quenching parameter?NPQ?,was negatively correlated with and the photochemical quenching parameter?q P?,but none of which had a significant correlation?P>0.05?;and significant positive correlation with relative electron transfer rate?ETR??P<0.05?,and had a significant correlation with the photosynthetic rate?P<0.05?.Thus,the photosynthesis prediction model on the basis of fluorescence parameters was P _prediction=0.1?PS?*PAR*0.5*X?The X factor represents the preset light energy absorption rate of the phenology?,The prediction model verification coefficient R²of different months is greater than 0.8,with model performance of experimental group set correlation coefficient R²=0.99 through the RBF neural model evaluation.