Effects Of Shading Treatment On Growth And Photosynthetic Characteristics Of Spuriopinella Brachycarpa (Kom.) Kitag.

In order to study the effect of shading on the growth,development,and quality of large leaf Spuriopinella brachycarpa（Kom.）Kitag.,this experiment was conducted at Jilin Agricultural University in Nanguan District,Changchun City,Jilin Province.Using large leaf Spuriopinella brachycarpa（Kom.）Kitag.as the experimental material,four shading treatments were set up,with one non shading control:non shading（CK）,20%shading（T1）,40%shading（T2）,60%shading（T3）,and 80%shading（T4）.The effects of different shading treatments on the growth and development,physiological indicators,photosynthetic indicators,yield and quality of large leaf Spuriopinella brachycarpa（Kom.）Kitag.were studied.Clarify the impact of shading on the cultivation and quality of large leaf Spuriopinella brachycarpa（Kom.）Kitag.,and provide theoretical basis and technical guidance for artificial cultivation techniques of large leaf Spuriopinella brachycarpa（Kom.）Kitag..The main research findings are as follows:（1）The experimental results showed that under shading treatment,the plant height,stem diameter,aboveground and underground dry and fresh weight of large-leaved Spuriopinella brachycarpa（Kom.）Kitag.increased to varying degrees compared to the control group.The plant height,stem diameter,leaf area,and aboveground and underground dry and fresh weight of large leaf Spuriopinella brachycarpa（Kom.）Kitag.showed a trend of first increasing and then decreasing with the increase of shading.Shading significantly increased the size of leaf area.After 65 days of planting,there was a significant difference in aboveground dry weight between 40%shading and the control.Overall,under 40%shading,the morphological indicators of large leaf Spuriopinella brachycarpa（Kom.）Kitag.are the best,with the highest plant height,stem diameter,and leaf area.It can be seen that shading has a certain promoting effect on the growth of Spuriopinella brachycarpa（Kom.）Kitag..（2）In terms of yield and quality,shading can significantly increase the yield of Spuriopinella brachycarpa（Kom.）Kitag.and improve its quality.The yield of 40%shading is the highest,reaching 1456.53kg·667m^-2.The yield of each treatment can be increased by 3.94%-71.87%compared to the control;In terms of quality,the soluble sugar content under 40%shading significantly increased by 60.78%compared to the control;The content of total flavonoids and total phenols in the 40%shade treatment was the highest,at 11.57mg·g^-1and 3.21mg·g^-1,respectively,significantly higher than the control treatment;The minimum cellulose content is 21.99mg·g^-1.Overall,40%shading has the highest yield and best quality.（3）In terms of photosynthetic characteristics,the research results show that all treatments can significantly increase the net photosynthetic rate of Spuriopinella brachycarpa（Kom.）Kitag.,with the net photosynthetic rate of 40%shading being the most significant,which is the most significant improvement compared to the control treatment.The results of diurnal changes in photosynthesis indicate that with the passage of time,the net photosynthetic rate,transpiration rate,and stomatal conductance all show a downward trend.In the morning,under 40%shading,they are significantly higher than other treatments,and the difference is not significant in the afternoon.The net photosynthetic rate is a single peak curve,and there is no phenomenon of“photosynthetic lunch break”;The intercellular carbon dioxide concentration shows a decrease followed by an increase over time;The transpiration rate is a bimodal curve;The stomatal conductance is a single peak curve;The water use efficiency is a bimodal curve.In summary,shading treatment can significantly improve the net photosynthetic rate,water use efficiency,reduce intercellular carbon dioxide concentration,and increase dry matter accumulation of large leaf Spuriopinella brachycarpa（Kom.）Kitag..Among them,40%shading is the most significant in improving photosynthesis.（4）As the growth period progresses,the chlorophyll content of each treatment increases;The activities of peroxidase（POD）and catalase（CAT）always showed a trend of first increasing and then decreasing with the increase of shading degree,with the most significant difference between 40%shading and the control;The control group had the highest levels of malondialdehyde（MDA）and proline（PRO）.Overall,the antioxidant enzyme activity is highest under 40%shading,with the lowest levels of MDA and PRO,and the plant has the best stress resistance.