水分胁迫对极小种群东兴金花茶幼苗光合特性的影响

Effests of water stress on photosynthetic characteristics of Camellia tunghinensis seedlings

关键词:  东兴金花茶, 不同控水时间, 光合作用, 叶绿素荧光参数, 种群扩散

Key words:  Camellia tunghinensis, different water control time, photosynthesis, chlorophyll fluorescence parameters, population dispersion

摘要:

为了解东兴金花茶幼苗对水分胁迫的适应能力和响应机制,该文以东兴金花茶1年生实生苗为材料,采用盆栽控水试验,研究不同控水时间处理对东兴金花茶幼苗的生理生态特性的影响。结果表明:随着控水时间的延长,水分胁迫的程度不断加剧,东兴金花茶叶片净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)呈现显著下降趋势; 胞间CO₂浓度(C_i)呈现先低后高的变化趋势,水分利用效率(WUE)呈现先高后低的变化趋势。土壤含水率和叶片相对含水量均呈现不断下降的趋势,丙二醛呈现先降后升的变化趋势; 东兴金花茶幼苗的荧光参数F_v/F_m和F_v/F_o呈现先增加后不断下降趋势,分别从0.806下降至0.754和4.17下降至3.08,表明水分胁迫降低了PS Ⅱ原初光能转化效率,光合作用原初反应过程受到抑制。基于水分胁迫的生理生态指标和叶片生物性状的变化表明,控水时间在4 d情况下东兴金花茶可以提高自身水分利用效率来抵抗干旱,说明东兴金花茶幼苗对水分胁迫具有一定的适应性和响应机制。控水8～12 d,东兴金花茶的光合指标下降显著,土壤含水率下降至14.157%～15.065%,其叶片萎蔫、打卷,低于此水平东兴金花茶幼苗会因过度干旱而死亡,表明东兴金花茶幼苗对水分胁迫的耐受极限土壤含水率为14.157%～15.065%。研究结果有助于营建适宜的环境以保证东兴金花茶的正常生长和繁殖,对东兴金花茶迁地保护、引种培育和回归自然具有重要的科学指导意义。

Abstract:

In order to understand the adaptability and response mechanism of Camellia tunghinensis seedlings to water stress, a pot experiment was conducted to study the effects of different water control time on the physiological and ecological characteristics of C. tunghinensis seedlings. The results were as follows: Net photosynthetic rate(P_n), stomatal conductance(G_s)and transpiration rate(T_r)decreased significantly with the extension of water control time and the aggravation of water stress; The variation trend of intercellular CO₂ concentration(C_i)was low first and then high, and water use efficiency(WUE)was high first and then low. Soil water content and leaf relative water content showed a decreasing trend, malondialdehyde first decreased and then increased; The fluorescence parameters F_v/F_m and F_v/F_o of C. tunghinensis seedlings first increased and then decreased continuously, from 0.806 to 0.754 and 4.17 to 3.08, respectively, which showed that water stress reduced PS Ⅱprimary light energy conversion efficiency, impaired the potential activity of PS Ⅱ, and inhibited the primary reaction process of photosynthesis. Based on the above changes of physiological and ecological indexes of water stress and biological characters of leaves,C. tunghinensis could improve its own water use efficiency to resist drought in the case of water control time of 4 d, indicating that seedlings had certain adaptability and response mechanism to water stress. In 8-12 d, the photosynthetic indexes of C. tunghinensis decreased significantly, and soil water content decreased to 14.157%-15.065%, which leaf wilting, curl, and lower than this level seedlings will die due to excessive drought, indicating that the tolerance limit of C. tunghinensis seedlings to water stress was 14.157%-15.065% of soil water content. The results of the study are helpful to the establishment of a suitable environment to ensure the normal growth and reproduction of C. tunghinensis, which is of important scientific significance to the conservation, cultivation and return to nature.