In this study,we investigated the biochemical mechanisms of red,yellow and green-colored leaves of Zelkova schneideriana in autumn,to provide theoretical foundation for the breeding and cultivation of fine lines.The leaf color index and the pigment composition,contents of chlorophyll,anthocyanin and carotenoid in red,yellow and green-colored leaves from three types of Zelkova schneideriana were investigated,and the correlation between them was analyzed.The results showed that,in autumn,the value of red-colored leaves chroma a* was the highest and reached the peak on October 25.The value of green-colored leaf chroma a* was low and the trend kept stable.In the later stage of autumn,the value of yellow-colored leaves chroma b* was significantly higher than red and green-colored leaves,but there was the phenomenon of returning green.The values of lightness L* and chroma C* had the similar trend to the values of chroma b*.The different colored-leaves all had chlorophyll,anthocyanin and carotenoid,but had different pigment composition.The red-colored leaves had the highest anthocyanin content,and reached 22.1%-44.6%.The green-colored leaves had the highest total chlorophyll content,and reached 73.0%-80.5%.The yellow-colored leaves had the highest carotenoid content,and reached 24.7%-35.4%.The multiple liner regression analysis showed that the contents of anthocyaninand chlorophyll played a decisive role in the three different colored leaves of Zelkova schneideriana.The content of anthocyanin was positively correlated with chroma a*,while negatively correlated with chroma L*,b* and C*.It was showed that increase of the anthocyanin content deepened the red color of leaves,meanwhile the lightness,yellow color and chroma of leaves were reduced.The content of chlorophyll was negatively correlated with chroma L*,a*,b* and C*.It was showed that increase of the chlorophyll content reduced the lightness,red color,yellow color and chroma of leaves.The content of carotenoid had not been introduced to the function,which showed that the carotenoid content was not significantly correlated with the value of leaf color parameters(P>0.05).The results showed that increase of the anthocyanin content and reduction of the chlorophyll content deepened the red color of leaves,reduction of the anthocyanin content and increase of the chlorophyll content kept leaves still green,and reduction of the anthocyanin and chlorophyll content deepened the yellow color of leaves.The content and percentage of chlorophyll,carotenoid and anthocyanin in the leaves were the material foundations and basic reasons for red,yellow and green-colored leaves.%探析红色、黄色、绿色3种不同色系榉树叶色形成的化学机制,为选育、培育榉树优良株系提供理论依据.以秋季转色期叶色表现为红色、黄色、绿色的榉树叶片为材料,分析其叶片的颜色参数及花青素、叶绿素、类胡萝卜素等色素含量的变化特点,并分析叶色与色素组成间的相互关系.结果表明:秋季叶片转色期,红色系榉树的色相a*值最高,在10月25日达到最大值,呈现出最佳观赏效果;绿色系榉树a*值较低,且变化趋势相对平缓;在转色后期,黄色系榉树的b*值显著大于红色和绿色系榉树,但其在秋季变色期存在返绿现象.明度L*值、彩度C*值与色相b*值的变化趋势几乎完全一致.不同色系榉树都含有花青素、叶绿素和类胡萝卜素,但不同色系榉树3种色素的含量不同.红色系榉树花青素含量百分比最高,为22.1%~44.6%;绿色系榉树的总叶绿素含量最高,为73.0%~80.5%;黄色系榉树的类胡萝卜素含量最高,为24.7%~35.4%.回归分析结果表明,榉树叶片中,花青素和叶绿素含量与榉树的叶片呈色密切相关.其中花青素含量与a*值呈正相关,与L*、b*、C*呈负相关,说明花青素含量的增加,使叶片红色度增加,同时明度、黄色度和彩度降低;叶绿素含量与L*、a*、b*、C*均呈负相关,说明叶绿素含量的增加,使叶片的明度、红色度、黄色度以及彩度均降低;类胡萝卜素含量未被引入方程,说明类胡萝卜素含量与叶片颜色参数无显著相关性(P>0.05).分析显示,花青素含量增加,叶绿素含量降低,可以使叶片变红;而花青素含量降低,叶绿素含量增加,叶片将维持绿色;若花青素与叶绿素同时降低,则将使叶片变黄.叶片内叶绿素、类胡萝卜素、花青素的含量及百分比是榉树呈现红色、黄色、绿色3种不同色系的物质基础和根本原因.
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