摘要
【目的】通过对2种树龄的巴山榧光合作用特性的研究,初步探讨光照条件对不同树龄巴山榧的影响,为深入揭示巴山榧濒危机制提供科学依据。【方法】本研究选址重庆市南川金佛山周家石窖次生林地,随机选取样地中生长良好的3年生和15年生巴山榧各3株,做好标记并测定其光合参数日变化、光响应曲线、CO_2响应曲线以及叶绿素含量。【结果】15年生巴山榧的叶绿素a、叶绿素b、类胡萝卜素含量均大于3年生巴山榧,其中叶绿素a和b的差异显著;3年生巴山榧的叶绿素a/b大于15年生巴山榧,差异不显著。15年生巴山榧净光合速率(Pn)、蒸腾速率(Tr)日均值显著大于3年生日均值;胞间CO_2浓度(Ci)日均值显著低于3年生日均值。15年生巴山榧光饱和时最大净光合速率(Pnmax)大于3年生;表观量子效率(AQY)、暗呼吸收速率(Rd)、光补偿点(LCP)小于3年生,光饱和点(LSP)大于3年生;3年生巴山榧CO_2饱和时Pnmax、羧化效率(CE)、光呼吸速率(Rp)、CO_2补偿点(CCP)、CO_2饱和点(CSP)小于15年生。【结论】3年生巴山榧光合系统结构完整,已具备较好的光合能力,在温度高、光照强的环境中,能及时启动"午休现象"以此来保护光合机构免于被破坏;但其不适应强光照射,在光合作用过程中能通过提高光呼吸速率以及对弱光较强的利用能力,以保持较高的光能转化效率。15年生巴山榧则对光照、CO_2利用幅度较宽,尤其在强光照射下,能及时启动"午休现象",增大蒸腾速率来使叶片免于灼伤;在弱光环境中还能通过降低暗呼吸作用的消耗以积累更多的有机物质,表现出对周围环境变化更强的适应性。
[Objective]This paper aims to provide a scientific basis for endangered mechanism of Torreya fargesii by studying its photosynthetic characteristics at different tree ages and discussing the effects of light conditions on the photosynthetic characteristics of T. fargesii. [Method]Three well-growing 3-yearold and 15-year-old T. fargesii,each of which was randomly selected and marked for testing in secondary woodland in Zhoujiashijiao of Jinfo Mountains in Chongqing Nanchuan of southwestern China. The daily photosynthetic parameters,light response curve,carbon dioxide response curve and chlorophyll content were measured in the sample plot. [Result]The results showed that the content of chlorophyll-a,chlorophyll-b and carotenoids of 15-year-old T. fargesii were higher than that of 3-year-old,and the difference of chlorophyll-a and chlorophyll-b was significant. The chlorophyll a/b of 3-year-old T.fargesii was higher than that of 15-year-old T. fargesii,with no significant difference. The mean daily values of Pnand Trof 15-year-old T. fargesii were significantly higher than that of 3-year-old T. fargesii,and the daily average of intercellular CO2 concentration was significantly lower than that of the 3-year-old T. fargesii. Pnmaxof 15-year-old T. fargesii when light saturation was higher than that of 3-year-old T.fargesii,while AQY,Rdand light compensation point were less than that of 3-year-old T. fargesii. Light saturation point of 15-year-old T. fargesii was higher than that of 3-year-old T. fargesii. The Pnmaxwhen CO2 was saturated,CE,Rp,the CO2 compensation points and the CO2 saturation point of 15-year-old T.fargesii were higher than that of 3-year-old T. fargesii. [Conclusion] 3-year-old T. fargesii has a complete photosynthetic system and good photosynthetic capacity. In an environment with high temperature and high light intensity,the"photosynthetic midday depression phenomena"can be activated in time to protect the photosynthetic apparatus from being damaged. However,it is not suitable with strong light,and it can maintain high light energy by increasing the photorespiration rate and utilizing the weak light during the photosynthesis process. 15-year-old T. fargesii has a wider range in light and CO2 utilization ability,especially in bright light. It can promptly start the "photosynthetic midday depression phenomena" to increase the transpiration rate to prevent the leaves from burning. In low light environments, it can also accumulate more organic matter by reducing the consumption of dark respiration,showing a greater adaptability to changes in the surrounding environment.
作者
高岚
乐佳兴
张文
吴焦焦
田秋玲
刘芸
Gao Lan;Yue Jiaxing;Zhang Wen;Wu Jiaojiao;Tian Qiuling;Liu Yun(College of Resources and Environment,Southwest University,Chongqing 400715,China)
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2018年第10期34-42,共9页
Journal of Beijing Forestry University
基金
重庆市林业重点科技攻关项目(渝林科研2016-7)
国家自然科学基金项目(31370602)
关键词
濒危植物
巴山榧
光合日变化
光响应曲线
CO2响应曲线
endangered plant
Torreya fargesii
diurnal variation of photosynthesis
photosynthetic lightresponse curve
photosynthetic C02 response curve