几种秋色叶树种秋冬转色期叶色变化的生理特性

Physiological Changes of Leaves of Several Fall Color Trees During Color Changing Period in Autumn and Winter

为了探索秋色叶树种秋冬转色期叶色变化的生理特性,于2011年10月10日到11月11日叶片转色期,对秋季叶色变红的火炬树,叶色变黄的银杏、栾树和叶色变为橙黄色的元宝枫叶片中的质体色素和可溶性糖质量分数进行了连续测定和分析,结果表明:不同树种叶片中叶绿素和类胡萝卜素的变化趋势一致,叶绿素a、叶绿素b及总叶绿素在转色期下降明显,前期下降快,后期变慢;类胡萝卜素质量分数略有上升,变化趋势较平缓;花色素苷质量分数在秋色叶变红的火炬树中显著上升,在秋色叶变黄的银杏、栾树及秋色叶变为橙黄色的元宝枫中均上升不明显。秋色叶树种在秋季转色期叶色的表达决定于不同色素间的比例。当叶片中叶绿素质量分数在60%以上时,叶片呈绿色;当叶绿素比例低于60%时,叶片的色彩决定于类胡萝卜素和花色素苷的比例,若二者之间有一种占有绝对优势,叶片表现为优势色素的色彩,否则,叶片呈现二者的混合色彩。可溶性糖质量分数在各树种中均表现为先升后降的单峰曲线;可溶性糖可能是花色素苷合成的前提物质。

Contents of pigment and soluble sugar in leaves of R.hus typhina L. , Ginkgo biloba L. , Koelreuteria paniculata Laxm. and Acer truncatum Bunge were determined continuously from 10 October to 11 November in order to explore the physiologi- cal changes of leaves of fall color trees during the color changing period in autumn and winter. Results indicated that the contents of ehlomphyU and carotenoid in the leaves of the four species of fall color trees shared the same changing trend. The contents of cldorophyll a, b and a＋b decreased obviously, which exhibited a quick decrease in the early stage and a slow decrease in the late stage. The contents of carotenoid increased slightly and the trend was subdued. The content of an- thoeyanin in R. typhina increased obviously when leaf color turned red in autumn and winter, and that in G. biloba, IC paniculata and A. truncatum did not increase significantly when leaf color turned yellow or orange yellow. Leaf color is de- pendent upon the pementage of different pigments, and the leaf color is green when the chlorophyll content is more than 60%. However, the leaf color is dependent upon the percentage of carotenoid and anthoeyanin when the chlorophyll con- tent is lower than 60%. The leaf color is red if the percentage of anthoeyanin is absolutely high, it is yellow if the percen- tage of carotenoid is absolutely high, and it is orange yellow if the percentage of carotenoid is similar to the percentage of anthoeyanin. In these four species, the contents of soluble sugar increased first and then decreased, which could be de- scribed by a unimodal curve. Soluble sugar might be the precondition for anthoeyanin synthesis.