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光强对三种喀斯特植物幼苗生长和光合特性的影响

王满莲,韦霄,唐辉,梁惠凌**,邹蓉   

  1. (广西壮族自治区中国科学院广西植物研究所, 广西桂林 541006)
  • 出版日期:2015-03-10 发布日期:2015-03-10

Effects of light intensity on growth and photosynthesis of three karst plant seedlings.

WANG Man-lian, WEI Xiao, TANG Hui, LIANG Hui-ling**, ZOU Rong   

  1. (Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and Chinese Academy of Sciences, Guilin 541006, Guangxi, China)
  • Online:2015-03-10 Published:2015-03-10

摘要:

以块根紫金牛、地枫皮和秀丽海桐的2年生幼苗为材料,通过搭建遮阴棚设置3个光照强度,对其不同光强下的形态结构、生物量分配以及光合特性进行了比较研究,以探讨光强对喀斯特植物幼苗生长和光合特性的影响。结果表明:遮阴促进了3种喀斯特植物幼苗株高、总叶面积和冠面积等形态指标的增长。总体而言,3种植物幼苗的根生物量比和根冠比均随光强的增大而显著增大,叶生物量比、叶面积比和比叶面积均随光强的增大而显著降低。强光显著降低了地枫皮与块根紫金牛的净光合速率(Pn),非气孔限制是其Pn下降的主要因素;秀丽海桐的Pn随光强的升高而显著增大。遮阴显著增加了地枫皮和秀丽海桐的单位面积叶绿素含量,强光显著增加了块根紫金牛的单位面积类胡萝卜素含量、叶绿素a/b和类胡萝卜素/叶绿素比。地枫皮和块根紫金牛在50%遮阴强度下的总生物量最大,秀丽海桐总生物量随光强增大而显著增大。3种喀斯特植物幼苗对不同的光环境表现出较强的适应性,但强光不利于地枫皮和块根紫金牛幼苗的生长,而秀丽海桐幼苗对光的适应性很强。
 
 

关键词: 水分利用效率, 光合日变化, 含水率, 光合特性, 断根

Abstract: In order to explore the effects of light intensity on the growth and photosynthesis of species distributed in the karst area, the morphology, biomass allocation and photosynthesis physiological characteristics of Ardisia corymbifera, Illicicum difengpi and Pittosporum pulchrum two-year-old seedlings were compared under 100%, 50% and 25% light levels. The results showed that shading environment facilitated the height, total leaf area and crown area of the three plant seedlings. Overall, the root mass fraction and root mass/crown mass ratio of the three species increased significantly, and leaf mass fraction, leaf area ratio and specific leaf area decreased significantly with the increase of light intensity. The net photosynthetic rate (Pn) of A. corymbifera and I. difengpi was significantly lower under full light than under shading environment, implying that stomatal restriction was the main factor leading to the decline of Pn. The Pn of P. pulchrum increased significantly with the increase of light intensity. With the increase of light, chlorophyll content per unit area of I. difengpi and P. pulchrum decreased significantly, while the carotenoid content per unit area, chlorophyll a/b and carotenoid/chlorophyll ratios of A. corymbifera increased significantly. The total biomass of A. corymbifera and I. difengpi seedlings reached the maxima under 50% shading, and the total biomass of P. pulchrum significantly increased with the increase of light intensity. These three karst plant seedlings adapted to different light conditions by different plant morphology and characteristics of photosynthesis. P. pulchrum preferred to strong light, while the seedlings of A. corymbifera and I. difengpi inclined to the shading environment.

Key words: photosynthetic characteristics, diurnal photosynthetic variation, root excision, moisture content, water use efficiency