Effects of Shading on Leaf Morphology, Photosynthetic Characteristics, and Growth of Ilex asprella

Abstract:

In order to explore the adaptability of Ilex asprella under shading environment, the growth, photosynthetic parameters, and biomass of I. asprella were studied under three light environments, including 85% shading, 56% shading, and full sunlight. The results showed that the contents of chlorophyll a, b, and a+b of I. asprella leaves significantly increased with shading intensity increment, while the content of carotene decreased significantly after one year shading. Compared with control, 56% shading significantly increased the maximum net photosynthetic rate by 17.6% and light saturation point by 25.2%, whereas 85% shading decreased the maximum net photosynthetic rate by 18.2% and light saturation point by 24.1%. The light compensation points significantly decreased under both 85% and 56% shading. The length, width, area, and water content of leaves, specific leaf area increased significantly under shading, but the leaf thickness reduced. The individual biomass and root shoot ratio significantly decreased under shading, but the response of plant height, crown area, and radial growth varied with the shading duration. Therefore, Ilex asprella is shade-tolerant and heliophilous species, it is critical to adjust the light transmittance of the canopy layer when planting in understory layer. Generally, the light transmittance of canopy should be greater than 44%.

Key words:Ilex asprella;Shade;Photosynthetic characteristics;Biomass