Effects of Shading Treatments on Growth of Asimina triloba( L. ) Dunal Seedlings

摘要

[Objective] The study was conducted to investigate the effects of shading treatments on growth of Asimina triloba (L) Dunal seedlings and provided the theoretical basis for seedling production. [Method]70 day-old A. triloba seedlings had similar stemdiameter and plant height and good growth vigour were taken as tested materials in 2005. 4 light gradient treatments which were the natural light with 100% light intensity, one-layer, two-layer and three-layer black shading network with the light transmittance rate of 50% , 25% and 12.5% were set up to study the effects of different shading treatments on growth of A. triloba. [ Result] With the shading treatments of one-layer and two-layer net, the plants of A. triloba seedlings grew rapidly. As the intensity of illumination decreased, the contents of chlorophyll a ( Chi. a) , chlorophyll b ( Chi. b) and total chlorophyll increased at first and then reduced. At the same time the chlorophyll a/b value became smaller. Under natural light, the plants tended to consume more water and the soil temperature at 15 ;00 p. m was higher. There was a smaller difference among various treatments. [Conclusion]The suitable shading treatment to the growth of A. triloba seedlings was under the light transmittance rateof 50% and height and stem diameter of trees increased fast. Chlorophyll a ( Chi. a) , chlorophyll b ( Chi. b) content in leaves of A. triloba seedlings were highest comparing with those in other conditions.