Effects of Shading on Photosynthetic Physiological Characteristics and Growth of Cunninghamia lanceolata Seedlings

In order to explore the characteristics of photosynthetic gas exchange parameters, non-structural carbohydrates, and nutrient accumulation in the leaves of Cunninghamia lanceolata seedlings under different shading environments, this study aimed to elucidate the light adaptation mechanism of C.lanceolata.6-month-old superior seedlings of C.lanceolata grown from seeds were subjected to five shading intensities: 0%（Z₀）,30%（Z₁）,50%（Z₂）,70%（Z₃）,90%（Z₄）.The growth, characteristics of photosynthetic gas exchange parameters, Rubisco enzyme activity, non-structural carbohydrate content in leaves, as well as mineral nutrient content in seedlings and soil were investigated.The results showed that the overall trend of seedling height increment, P_n,T_r,G_s and C_i increased at first and then decreased with the increase of shading intensity, whereas the increment of ground diameter decreased gradually with the increase of shading intensity, and the activity of Rubisco increased with the increase of shading intensity; under Z₂ treatment（50% shading）,the non-structural carbohydrate content in the leaves was the highest, which was significantly higher than that of full light and 90% shading, with increases of 7.7% and 76.9%,respectively; shading treatment increased the contents of phosphorus, manganese, magnesium, calcium, and potassium in seedlings, while decreased iron content.However it had no significant effect on soil mineral nutrient contents.In conclusion, light intensity significantly affected the growth of seedling height and ground diameter of C.lanceolata,and moderate shading（50%）enhanced the photosynthetic capacity and improved the growth of C.lanceolata seedlings, thereby improving seedling quality.