Abstract: In the process of soil natural continuous drought, the photosynthetic characteristics, chlorophyll fluorescence parameters and corresponding soil moisture content of Zizania latifolia and Phragmites australis leaves were investigated to explore the photosynthetic physiological response of Z. latifolia and P. australis leaves to soil continuous drought stress. Pn, Tr, Gs of Z. latifolia leaves were first increasing and then decreasing, and those of P. australis leaves were gradually decreasing. Ci, Fv/Fm, NPQ, WUE, Yield, ETR and qP of Z. latifolia and P. australis leaves were the same change trend, Ci was gradually increasing, Fv/Fm, NPQ and WUE were first increasing and then decreasing, Yield, ETR and qP were gradually decreasing, with the soil moisture content gradually decreasing. It was showed that non-stomatal limitation was responsible for Pn reduction of Z. latifolia and P. australis leaves, confronting with severe drought stress. Drought stress threshold of Z. latifolia was between (2.17 ? 0.18)% and (1.66 ? 0.23)% of soil water content, that of P. australis was between (1.84 ? 0.17)% and (0.25 ? 0.07)% of soil water content, with 19% field capacity of growth substrate, available nitrogen, phosphorus and potassium of 28.14, 2.25 and 25.76 mg穔g-1 respectively, and pH 7.2.

Key words: soil continuous drought, Zizania latifolia, Phragmites australi, photosynthetic characteristics parameters, chlorophyll fluorescence parameters

摘要： 对茭草Zizania latifolia和芦苇Phragmites australi进行自然持续干旱处理，测定植物叶片光合作用特征参数和叶绿素荧光参数及相应的土壤水分含量，探讨茭草、芦苇叶片对土壤持续干旱胁迫的光合生理响应。随着土壤水分逐渐减少，茭草叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)均先增大后减小，芦苇叶片的Pn、Tr、Gs均逐渐减小；茭草和芦苇叶片的胞间二氧化碳浓度(Ci)、光化学最大量子效率(Fv/Fm)、非光化学猝灭系数(NPQ)、水分利用率(WUE)、有效荧光产量(Yield)、电子传递速率(ETR)、光化学猝灭系数(qP)变化趋势一致，其中Ci逐渐增大，Fv/Fm、NPQ、WUE先增大后减小，Yield、ETR、qP逐渐减小。分析表明，当茭草和芦苇遭遇较严重干旱时，叶片Pn下降主要是非气孔限制因素导致；当生长基质(沙土)的田间持水量为19%，速效氮、磷、钾分别为28.14、2.25、25.76 mg·kg-1，pH 7.2时，茭草的干旱胁迫阈值在土壤含水量(2.17 ± 0.18)%和(1.66 ± 0.23)%之间，芦苇的干旱胁迫阈值在土壤含水量(1.84 ± 0.17)%和(0.25 ± 0.07)%之间。

关键词: 土壤持续干旱, 茭草, 芦苇, 光合作用特征参数, 叶绿素荧光参数