山栀子幼苗表型可塑性对不同光环境的响应

通过遮荫设置5个光照强度(100%、52%、33%、15%和6%),研究不同光环境下山栀子幼苗形态、生物量积累及其分配,以及叶绿素含量和光合特性的响应。结果表明,随遮荫程度增加,叶长、叶宽和叶长/叶宽变化幅度较小,单株总叶面积显著减少,比叶面积则随光照有效性降低逐渐增大;叶绿素a、总叶绿素和类胡萝卜素含量在遮荫处理(除33%相对光照处理)中显著增加,但叶绿素b含量和叶绿素a/b在不同光环境中没有显著差异;最大净光合速率、光饱和点、光补偿点也随光照有效性降低显著减小。山栀子叶、枝、干、根及总生物量均显著降低,但地上、地下生物量的分配格局并不随光环境的变化发生显著改变。总体上,山栀子叶性状(叶面积和光合参数)具有较高的表型可塑性,而结构性状(生物量分配)可塑性较低。适度遮荫(52%相对光照)不会显著影响山栀子幼苗的生长,这对今后山栀子的复合经营和栽培提供了参考依据。

Effects of Light Intensity on Phenotypic Plasticity of Gardenia jasminoides Seedlings

The morphology,biomass accumulation and allocation,leaf chlorophyll content and photosynthe-sis of Gardenia jasminoides seedlings were compared under five controlled light conditions( 100%,52%,33%, 15%and 6%) using artificial shade houses.The results showed that leaf length,leaf width and leaf length/leaf width varied not so much with increasing shade level,total leaf area significantly decreased with the reduction of light efficiency,and specific leaf area increased gradually.The contents of chlorophyll a,total chlorophyll and carotenoid significantly increased in shade treatments( except 33%relative light treatment) compared with the 100%light treatment,the chlorophyll b content and chlorophyll a/b were not significantly different in the five light environments.The maximum net photosynthetic rate,light saturation point and light compensation point significantly decreased with the reduction of light efficiency.Leaf,branch,stem,root and total biomass of G.jas-minoides also had similar change trend with photosynthetic variables,but the pattern of the aboveground,un-derground biomass allocation varied not so much with the light environment.On the whole,leaf traits( especially leaf area and photosynthetic variables) of G.jasminoides had a higher phenotypic plasticity,and structural plas-ticity( biomass allocation) was lower.These results showed that moderate shade ( 52%relative light) did not affect the growth of G.jasminoides,which will be useful to management and cultivation of G.jasminoides in the future.