遮荫对彩叶植物矾根夏季适应性表型的影响

以彩叶植物矾根(Heuchera micrantha)‘蜜桃’(‘Georgia Peach’)、‘小珍珠’(‘Petite pearl fairy’)、‘花毯’ (‘Tapestry’)为材料，研究不同遮荫处理对矾根观赏特征、高温半致死温度以及成活率的影响。结果表明，在遮荫条件下，三个矾根品种株高增加、叶面积变大、花序变长、开花推迟，‘蜜桃’和‘小珍珠’花期延长，‘花毯’花期缩短。遮荫引起‘蜜桃’和‘小珍珠’叶绿素含量、类胡萝卜素含量显著上升，花色素苷含量明显下降，叶色由红、紫色向灰绿色转变，叶片彩化度下降；‘花毯’的叶绿素、类胡萝卜素和花青素含量均随遮荫度增加显著上升，其叶色由浅绿转为深绿，叶脉紫红色加重，彩化度提高，观赏性增强。随着遮荫度提高，三个矾根品种的高温半致死温度明显升高，成活率显著上升。相关性分析表明，三个矾根品种的成活率与最高气温、最大光强、气温、光强分别存在极显著负相关关系，与相对湿度以及该品种的高温半致死温度分别存在极显著正相关关系。多元逐步回归分析表明，高光强是引起‘蜜桃’成活率下降的关键因素，‘小珍珠’的成活率主要取决于高温半致死温度，‘花毯’的成活率主要受极端高温的影响。

Effect of Shading on Adaptive Phenotype of Color-leafed Heuchera micrantha in Summer

Three Heuchera micrantha cultivars, ‘Georgia Peach’, ‘Petite pearl fairy’, ‘Tapestry’, were used to investigate the influence of shading on ornamental characteristics, semi-lethal high temperature and survival rate. Results showed that shading resulted in increase of the height, leaf area and inflorescence length, but delay of flowering of the three cultivars to varying degrees. The flowering period of ‘Georgia Peach’ and ‘Petite pearl fairy’ lengthened while that of ‘Tapestry’ shortened in response to shading treatment. With the increase of shading degree, the contents of chlorophyll and carotenoid in ‘Georgia Peach’ and ‘Petite pearl fairy’ increased significantly but the anthocyanin content declined evidently. Accordingly, the leaf color turned from red or purple to grey and green. In a different way, the contents of chlorophyll, carotenoid and anthocyanin in ‘Tapestry’ rose obviously under shading condition and the leaf developed into dark green with crimson leaf vein. The semi-lethal high temperature and survival rate of the three cultivars increased remarkably with the promotion of shading degree. Correlation analysis revealed that there were extremely significant negative correlations between survival rate and extreme high temperature, extreme high light intensity, air temperature and light intensity, respectively. Instead, there were extremely significant positive correlations between survival rate and relative humidity and semi-lethal temperature, respectively. Multiple linear regression analysis showed that high light intensity was the key factor for the decrease of survival rate in ‘Georgia Peach’ whereas the survival rate of ‘Petite pearl fairy’ and ‘Tapestry’ in summer mainly depended on the semi-lethal high temperature and extreme high temperature, respectively.