植物生态学报 ›› 2017, Vol. 41 ›› Issue (3): 369-377.doi: 10.17521/cjpe.2016.0098

• 研究论文 • 上一篇    下一篇

杨树根压昼夜周期性及其影响因子

郭建荣, 万贤崇*()   

  1. 中国林业科学研究院林业新技术研究所, 北京 100091
  • 出版日期:2017-03-10 发布日期:2017-04-12
  • 通讯作者: 万贤崇 E-mail:wxc@caf.ac.cn
  • 作者简介:

    * 通信作者Author for correspondence (E-mail:sunzhiqiang1956@sina.com)

  • 基金资助:
    国家自然科学基金(31270648)

Circadian rhythm of root pressure in popular and its driving factors

Jian-Rong GUO, Xian-Chong WAN*()   

  1. Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing 100091, China
  • Online:2017-03-10 Published:2017-04-12
  • Contact: Xian-Chong WAN E-mail:wxc@caf.ac.cn
  • About author:

    KANG Jing-yao(1991-), E-mail: kangjingyao_nj@163.com

摘要:

为研究土壤盆栽和溶液培养的‘84K’ (Populus alba × P. glandulosa)离体根系的根压及根压昼夜节律, 系统探讨影响根压的因素及它们与根压的关系, 深入了解根压的产生机制及其节律调控, 采用压力转换器法对‘84K’离体根系的根压进行了研究。该研究采用不同时间取样、摘叶、环割等试验处理, 不同土壤温度、昼夜温差/恒温等测定条件研究了离体根压的节律, 并进一步运用化学抑制剂研究根系呼吸代谢、根系导水率对根压的影响, 并测定伤流液的渗透强度及其无机离子和可溶性糖含量日变化以探讨它们和根压昼夜节律的关系。研究发现, ‘84K’离体根系的根压具有昼高夜低的周期节律, 在上午至正午达到峰值, 在20:00达到谷值。不同取样时间、不同培养介质对根压周期性有一定的影响, 但总体昼高夜低没有改变。摘叶、环割、呼吸抑制剂或细胞膜水导抑制剂影响根压峰值的大小, 但对根压的昼夜节律没有明显影响。摘叶、环割或呼吸抑制剂显著地降低了根压峰值, 而水导抑制剂对根压峰值影响不大, 说明根压峰值的大小主要受呼吸作用, 包括呼吸底物的影响, 而根系水导率对根压峰值的影响不大。根压峰值随土壤温度下降而下降、土壤温度还改变根压的昼夜节律。随温度的变化, 最大根压和呼吸速率同步变化, 意味着根压随温度的变化也是呼吸代谢在起作用。根系伤流液渗透强度白天高晚上低。伤流液无机离子含量以及可溶性糖含量的日变化和渗透强度变化一致, 其中无机离子扮演更主要的角色。昼夜温差条件下的根压峰值显著大于昼夜常温条件下的根压峰值。总之, ‘84K’根压呈现较稳定的昼夜周期性, 昼高夜低。根压峰值大小主要受呼吸代谢的调控, 呼吸抑制剂、呼吸代谢底物、影响呼吸作用的温度等都影响‘84K’根压峰值的大小。根系导水率对根压有一定的影响, 但不显著。

关键词: 根压, 离体根系, 日周期, 影响因素

Abstract:
Aims Our main purposes were to investigate root pressure and its circadian rhythm of excised roots in ‘84K’ popular (Populus alba × P. glandulosa) cultured in soil and solution, to explore the influencing factors and their relationships with root pressure systematically and to understand the generation and rhythm regulation of root pressure. Methods We investigated the root pressure of excised roots in ‘84K’ popular using the method of digital pressure transducer. The diurnal rhythm of excised roots was conducted through different experimental treatments including sampling in different time, defoliation and girdling, together with ambient condition like soil temperature, differential or consistant temperature during day and night. Then we discussed the effects of root respiration and hydraulic conductivity on root pressure by further using chemical inhibitor. Furthermore, diurnal variation of osmotic potential and ions content as well as soluble sugar content of exudation was determined in order to explore their relationships with root pressure rhythm. Important findings Root pressure of excised roots in popular had diurnal rhythm which was higher during daytime and lower overnight. It reached its peak value in the morning to noon and valley value at 20:00. Root pressure of excised roots sampled at different time and cultured in different medium had influence on the rhythm of root pressure to some degrees, but did not the general rhythm of high in daytime and low overnight. Defoliation, girdling and the inhibitors for root respiration or cytomembrane hydraulic conductivity could affect the maximum value of root pressure while have no significant influence on the daily rhythm. Defoliation, girdling and respiration inhibitor reduced the maximum value of root pressure, whereas the hydraulic conductivity inhibitor had little influence on root pressure. The maximum value of root pressure declined with the decrease in soil temperature which could change the rhythm of root pressure. The synchronous change in the maximum value of root pressure and root respiration rate with temperature indicated that root respiration contributed to the change of root pressure along with temperature. Osmotic potential of root exudation was higher during the daytime and lower at night. Diurnal variations of ions and soluble sugar content of exudation were consistant with that of osmotic potential. The peak of root pressure measured under the condition of differential temperature during day and night was significant higher than that measured under constant temperature. In conclusion, root pressure of the poplar ‘84K’ showed significant diurnal rhythm, i.e. higher during the daytime and lower at night. The maximum value of root pressure was mainly regulated by root respiration metabolism. The factors such as respiration inhibitor, respiration substrate and temperature influence the value of the maximum root pressure of poplar ‘84K’. Root hydraulic conductivity had no significant influence on root pressure.

Key words: root pressure, excised roots, diurnal rhythm, influencing factors