Responses of plants exposed to drought and rewatering have been well documented; however, little is known concerning strategies of psammophyte to drought and rewatering under different soil nutrient regimes. For this study, Pennisetum centrasiaticum under two soil nutrient regimes was subjected to progressive drought and subsequent rewatering. Soil water status, gas exchange characteristics, chlorophyll a fluorescence characteristics as well as biomass traits were measured to investigate ecophysiological responses. Net photosynthesis rate ( P _n), stomatal conductance ( g _s), water use efficiency, maximum quantum efficiency of photosynthesis system II (PSII, F _V/ F _M), electron transport flux per cross section (ET₀/CS₀), and performance index on cross section basis (PI_CS) were suppressed during drought periods for both nutrient regimes. Meanwhile, leaf intercellular CO₂ concentration ( C _i ), minimal fluorescence intensity ( F ₀), and dissipated energy flux per cross section (DI₀/CS₀) increased. Reversible downregulation of PSII photochemistry and enhanced thermal dissipation of excess excitation energy (DI₀/CS₀) contributed to enhanced photo-protection in drought-stressed plants. Thus, the results indicate that P. centrasiaticum is capable of withstanding and surviving extreme drought events, and the recovery pattern of stressed P. centrasiaticum under both nutrient regimes was similar. However, fertilization increased the biomass and the variation in gas exchange and chlorophyll a fluorescence characteristics during drought periods. Additionally, fertilization accelerated the process of drought and aggravated stress under extreme drought events. Thus, the fertilization strategy used in P. centrasiaticum restoration should be carefully selected—fertilization may not always be beneficial.

中文翻译：

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不同土壤养分状况下干旱和复水的 白草的 光合性能和生长性状。

干旱和补水对植物的反应已得到充分证明；然而，关于在不同土壤养分条件下沙生植物抗旱和补水的策略知之甚少。在本研究中， 在两种土壤养分制度下的 白草狼尾草 都受到了持续干旱和随后的补水。测量了土壤水分状况，气体交换特征，叶绿素 a 荧光特征以及生物量特征，以研究生态生理响应。净光合作用率（ P _n），气孔导度（ g _s），水分利用效率，光合作用系统II（PSII， F _V）的最大量子效率 / F _M），两种横截面的养分模式都抑制了干旱期间每个横截面的电子传输通量（ET ₀ / CS ₀）和横截面性能指数（PI _CS）。同时，叶片的细胞间CO ₂浓度（ C _i ），最小荧光强度（ F ₀）和每个截面的耗散能量通量（DI ₀ / CS ₀）增加。PSII光化学的可逆下调和过量激发能（DI ₀ / CS _0的增强的散热） ）有助于增强干旱胁迫植物的光保护作用。因此，结果表明 P. centrasiaticum 能够抵御和生存极端干旱事件，并且在两种营养体系下应激 P. centrasiaticum 的恢复模式 都相似。但是，在干旱时期，施肥增加了生物量，气体交换和叶绿素 a 荧光特性也发生了变化 。此外，在极端干旱事件下，施肥加速了干旱进程并加剧了压力。因此，应该仔细选择在 百日草 修复中使用的施肥策略 -施肥可能并不总是有益的。