水分胁迫对辣椒光合作用及相关生理特性的影响

Effects of Water Stress on Photosynthesis and Associated Physiological Characters of Capsicum annuum L.

【目的】研究水分胁迫对辣椒光合作用及相关生理特性的影响,揭示水分胁迫与辣椒光合作用及生理指标之间的关系,为辣椒栽培管理,抗性筛选提供理论参考。【方法】采用盆栽的方式,分别在正常供水和水分胁迫条件下,研究辣椒生长形态及相关生理指标,光合参数,叶绿素荧光参数,叶片气孔特征及叶绿体超微结构的变化。【结果】水分胁迫显著抑制了辣椒的生长,植株总的干物质含量下降,并且干物质含量向根的分配比例增加,向茎叶的分配比例减少。叶片水势(Ψ)、叶片相对含水量(RWC)、叶绿素(Chl.)及类胡萝卜素(Car.)的含量显著下降,叶片中丙二醛(MDA)含量,游离脯氨酸(Pro)的含量,超氧化物歧化酶(SOD),过氧化物酶(POD)的活性均有所提高。叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)、PSⅡ光化学量子效率(ΦPSⅡ)、光化学猝灭系数(qP)及光合电子传递速率(ETR)均下降,非光化学猝灭系数(NPQ)和水分利用效率(WUE)提高。水分胁迫后叶片气孔密度、气孔长度、气孔宽度均有所下降,大部分气孔关闭深陷。叶绿体变圆,基粒片层和基质片层弯曲排列紊乱,淀粉粒减少或消失。【结论】水分胁迫下辣椒光合速率的下降主要是由气孔限制引起的。光合参数、叶绿素荧光参数、叶片气孔特征以及叶绿体超微结构的变化与品种的抗性密切相关。

[Objective] The effects of water stress on photosynthesis and associated physiological characters of capsicum were studied, the aims were to reveal the relationship between photosynthetic traits and drought tolerance of two cultivars. [Method] The experiment was conducted under two water levels： no stress （75%-80% of field capacity） and stress （30%-40% of field capacity）. The responses of plants growth, physiological changes, photosynthetic parameters, chlorophyll fluorescence, stomatal characters, ultrastructure of chloroplast were investigated. [Result] The results showed that, under the water stress condition, the growth of the plants was inhibited, the total plant dry weight declined significantly, and root/shoot increased. Leaf water potential, leaf relative water content and leaf pigment decreased, the contents of malondialdehyde, the proline as well as the activities of superoxide dismutase and peroxidase increased. The Pn, Gs, Tr, Ci, ФPSII, ETR and qP decreased, but the NPQ and WUE increased. The stomata became smaller and the density decreased, and most of them closed. The chloroplasts became round in shape, the lamellae arranged disorderly and the number of starch grain decreased or disappeared. [Conclusion] The decrease of net photosynthetic rate was considered as a result of stomatal restriction. The changes of photosynthetic parameters, chlorophyll fluorescence, stomata characters and the ultrastructure of chloroplast correlated significantly to drought resistance.