Responses of the Morphological and Photosynthetic Characteristics of Impatiens oxyanthera to Light Intensity and Evaluation of its Shade-tolerance

Evaluating shade-tolerance of wild flower plants contributed to effective introduction and cultivation as well as reasonable utilization of plant resources.In this study,the wild ornamental plant (Impatiens oxyanthera) was grown in two different light environments (unshading and shading at (26.242±1.029)% with black shading net) in E'mei Mountain for about 4 months.The morphological,and gaseous exchange characteristics were measured and photosynthetic-light curve parameters were calculated.The results showed that shading significantly promoted the growth of I.oxyanthera,which increased plant height,base diameter,branch number,crown width,single leaf area,leaf length and width.Shading significantly reduced net photosynthetic rate due to the decrease of the transpiration rates and stomatal conductance,but had no obvious effect on the other gas exchange traits,such as intercellular CO₂ concentration,water use efficiency and stomatal limit.In addition,shading significantly increased apparent quantum yield by 69.841%.The comprehensive evaluation of shade-tolerance of I.oxyanthera showed that average comprehensive evaluation value was 0.407 by principal component analysis and subordinate function method.This suggested that I.oxyanthera had a good resistance to shade,and could adapt to low light environment through improving single leaf area to make up for the reduction of net photosynthetic rate per unit area and increasing apparent quantum yield.Higher shade-tolerance would have an important application value for garden-plant scenery and greening at the shading areas of buildings.