黄叶银杏叶色发育及光合特性研究

目的]研究黄叶银杏的叶色发育及光合特性。方法]以1年生嫁接黄叶银杏为材料,研究了叶色表达期叶色,叶中叶绿素（Chl）、类胡萝卜素（x.c）含量及其比值变化,以及全光照和遮阴下光合特性。结果]黄叶银杏新生芽浅黄色,4月为橙黄色至金黄色,5月为浅黄绿色,6~10月黄绿色,11月为黄色。黄叶中Chla、Chlb和x.c含量明显低于绿叶中对应色素含量,Chla/x.c、Chlb/x.c明显低于绿叶中对应色素含量比值。在叶色发育过程中,黄叶Chla、Chlb和x.c含量升高,Chla/x.c、Chlb/x.c比值增大。自然光下银杏叶片饱和光强高于遮阴的叶片。黄叶最大净光合速率、光补偿点和暗呼吸速率均明显高于绿叶。遮阴黄叶Chla/x.c、Chlb/x.c、Chla＋b/x.c高于自然光下叶中对应色素间的比值。结论]黄叶银杏的最佳观赏期是4、5月。黄叶Chla/x.c、Chlb/x.c明显低于绿叶是其呈现黄色的主要原因。在叶色发育过程中,Chla/x.c、Chlb/x.c比值增大是黄叶转为黄绿色的原因。遮阴黄叶中Chlb含量高于自然光下的叶片,是对遮阴的一种适应性反应。遮阴黄叶Chla/x.c、Chlb/x.c、Chla＋b/x.c较高,是遮阴黄叶较绿的原因之一。

Preliminary Study on Leaf Color Development and Photosynthetic Characteristics of Golden-leaf Ginkgo

Objective] The aim of this study is to research leaf color development and photosynthetic characteristics of golden-leaf ginkgo.Method] With one-year-old grafted seedlings of golden-leaf ginkgo as the materials,the changes of leaf color,chlorophyll content(Chl),carotenoid(x.c) content and rate of chlorophyll and carotenoid content,as well as photosynthetic characteristics under full sunlight and overshadowing were all investigated in this study.Result] Sprouts of golden-leaf ginkgo were pale-yellow,and changed from orange to golden in April,to light yellow-green in May,to yellow-green from June to October,to yellow in November.The chlorophyll and carotenoid contents and the rates of chlorophyll and carotenoid contents of yellow-leaf were significantly lower than that of green-leaf,while the rate of Chla/x.c and Chlb/x.c was obviously lower than the corresponding pigment content of green-leaf.During the leaf color development,Chla,Chlb and x.c content as well as the rate of Chla/x.c and Chlb/x.c of yellow-leaf ginkgo all increased.The saturation light intensity of ginkgo leaf under natural light was higher than that under overshadowing.Maximum net photosynthetic rate,light compensation point and dark respiration rate of yellow leaf were all significantly higher than that of green leaf.Chla/x.c,Chlb/x.c and Chla+b/x.c of yellow-leaf ginkgo under overshadowing were higher than the corresponding pigment rate of leaf under natural light.Conclusion] The best ornamental duration of golden-leaf ginkgo is April and May.The major reason for showing yellow leaf is that Chla/x.c and Chlb/x.c of yellow-leaf is obviously lower than that of green-leaf.During the leaf color development,the major reason for yellow-leaf turning to yellow-green is that the rate of Chla/x.c and Chlb/x.c increases.Chlb content of yellow-leaf under overshadowing is higher than that under natural light,which is an adaptive response to overshadowing.Chla/x.c,Chlb/x.c and Chla+b/x.c of yellow-leaf under overshadowing are relatively higher,which is one of the reasons why yellow-leaf under overshadowing becomes yellow-green or green.