洒金柏色素变化及光合作用响应特征

为揭示洒金柏叶色变化生理机制,以期为常色叶园林植物品种选育和推广提供参考依据,以侧柏变种洒金柏优良单株为试材,研究了枝条顶部黄叶和基部绿叶在生长期的叶色动态变化、色素含量及光合作用响应特征。结果表明：3—10月期间,洒金柏黄叶颜色呈现黄—绿—黄的动态变化过程,夏季出现一定程度的返绿现象。相同月份黄叶叶绿素a(Chl a)、叶绿素b(Chl b)、总叶绿素(Chl)、类胡萝卜素(Car)含量均显著低于绿叶,类胡萝卜素与总叶绿素(Car/Chl)含量比值高于绿叶。2种叶片Chl含量呈先升高后降低趋势,Car含量先降低、随后变化平缓、最后急剧上升。另外,黄叶的光饱和点低于绿叶,相同光强下,黄叶的净光合速率(Pn)显著低于绿叶;光合指标随时间基本呈先上升后降低趋势,3—8月黄叶的Pn显著低于绿叶。而且,光合指标与Chl含量呈显著正相关性,与Car/Chl含量比值呈显著负相关性。综合分析得出洒金柏叶片呈现黄色可能是Car/Chl含量比值较绿叶高导致。

Pigment Change and Photosynthetic Response Characteristics of Plantycladus orientalis cv. Semperourescens

To reveal the physiological mechanism of leaf color change in Plantycladus orientalis cv. Semperourescens and to provide reference for the breeding and promotion of evergreen varieties in landscaping, the single individual of P. orientalis cv. Semperourescens, which is varietas of P. orientalis, was used as the test material, and the dynamic changes of leaf color, related pigment content and photosynthetic response characteristics of yellow leaves on the top of branches and green leaves at base during the growth period were studied. The results showed that from March to October, there was a dynamic change process of yellow-green-yellow in the yellow leaves of P. orientalis cv. Semperourescens, and a certain degree of greening in summer. In the same month, chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl) and carotenoid (Car) content in yellow leaves were significantly lower than those in green leaves, while, the ratio of Car to total chlorophyll (Car/Chl) content in yellow leaves was higher than that in green leaves. Chl contents first increased and then decreased both in yellow and green leaves, while Car contents first decreased, followed by a gentle change and then a sharp rise. In addition, the light saturation point of yellow leaves was lower than that of green leaves. The net photosynthetic rate (Pn) of yellow leaves was significantly lower than that of green leaves under the same light intensity. The photosynthetic index showed a trend of first increasing and then decreasing along with the time. Pn of yellow leaves from March to August were significantly lower than that of green leaves. Furthermore, there was a significantly positive correlation between photosynthetic index and Chl content, and a significantly negative correlation between photosynthetic index and Car/Chl content ratio. In conclusion, the yellow color of the leaves of P. orientalis cv. Semperourescens might be caused by the high ratio of Car/Chl content.