The Influence Of Shade On The Growth Of Seedlings And Physiological-biochemical Characteristics Of Three Ground Cover Plants

This thesis is a study on shade tolerance of three ground cover plants--Echinops sphaerocephalus L, Orychopeagmus violaceus L and Viola philippica Car, whose seedlings are identified by the growth index, physiological index and photosynthetic index through five levels of shade( separately the shade of 0%, 30%, 50%, 70% and 90%). With an analysis of subordination function, the author makes a comprehensive assessment of shade tolerance of ground cover plants as well as screens the identification indexes in order to make the future study more efficient and convenient. The experimental results are as follows:(1) By studying the shading effects on growth index: in general, under different light conditions, the leaf length, width, area and plant height increase with the shade.(2) By studying the shading effects on physiological index:the content of a+b and the relative plasma membrane permeability of chlorophyll increase with the shade and its duration: while the POD takes on a "V" shape trend, and the shade has relative less influence on soluble protein and MDA.(3) By studying the shading effects on the Diurnal change of photosynthetic :Net photosynthetic rate, Stomatal conductance, Intercellular CO2 concentration,and Transpiration rate all take on a single-peak curve, and the top or bottom of the peak appears at 13: 00, all of which are closely related with shade tolerance.(4) Determined the growth range of the three ground cover plants: Orychophragmus violaceus L. Can grow large range of illumination than Viola philippica Car., Viola philippica Car. Can grow large range of illumination than Echinops sphaerocephalus L.Orychophragmus violaceus L. from all optical illumination to 90% shade degree can be normal growth. The most optimal illumination is 70% shade degree. Viola philippica Car. all optical illumination to 70% shading can be normal growth. The most optimal illumination is 70% shade degree. 50% shading is the most optimal illumination, In 0%/30% and 70% shading is the extent of Echinops sphaerocephalus L. could bear.(5) The author ranks the three tested ground cover plants through the subordination function analysis of the three indexes mentioned above, and shade tolerance decreases on Orychophragmus violaceus L, Viola philippica Car. and Echinops sphaerocephalus L in order. The author screens shade tolerance research indexes about the three ground cover plants.