ABSTRACT

Introduction.

We hypothesised that a prehydration period (exposure to humid air) should mitigate the damaging effects of short or long periods of desiccation in a desert moss, Syntrichia ruralis.

Methods.

Cultured uniclonal shoots of S. ruralis were dried rapidly, equilibrated at 42% relative humidity (RH), allowed to remain at this RH for 1–50 days, and either (1) prehydrated (24 h at 100% RH) then rehydrated with liquid water, or (2) rehydrated directly using liquid water without a prehydration treatment, and assessed using chlorophyll fluorescence and visual damage.

Key results.

At both 20 min and 24 h postrehydration, all chlorophyll fluorescence measures (F_m, F_v/F_m, Φ_PSII, qP) were higher in shoots that were prehydrated. Prehydrated S. ruralis shoots also had less visual leaf damage 7 d postrehydration. Duration-dry (DD) had an overall negative effect for all fluorescence measures on shoots immediately after rehydration, an effect that dissipated at 24 h postrehydration in three of the four fluorescence measures (F_m, F_v/F_m, Φ_PSII). Leaf damage was not influenced by Duration-dry. Although no interaction was detected between Prehydration and Duration-dry treatments, the benefits of prehydration were accentuated based on fluorescence metrics F_v/F_m and Φ_PSII, when shoots are exposed to longer drying periods.

Conclusions.

A prehydration treatment implemented just prior to hydration with liquid water significantly mitigated shoot damage accrued from a prior rapid drying event and DDs of up to 50 d at 42% RH. Based on photosynthetic efficiency, prehydration conferred greater effects at longer DDs. Experiencing humid conditions prior to rainwater mitigates damage incurred during prolonged desiccation.

中文翻译：

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预水化可减轻因长时间干燥而对 Syntrichia 乡村植物的茎尖造成的损害

摘要

介绍。

我们假设预水合期（暴露于潮湿空气中）应减轻沙漠苔藓（Syntrichia乡村）中短期或长期干燥的破坏性影响。

方法。

的培养的枝条uniclonal S.螟迅速干燥，在42％相对湿度（RH），允许保持在该RH下1-50天平衡，或者（1）预水合（在100％RH 24小时），然后用再水合液态水，或 (2) 直接使用液态水再水化而不进行预水化处理，并使用叶绿素荧光和视觉损伤进行评估。

关键结果。

在再水化后 20 分钟和 24 小时，所有叶绿素荧光测量值（F _m、F _v / F _m、Φ _PSII、qP）在预水化的枝条中都较高。预水化的S. countryis枝条在再水化后 7 天也具有较少的可见叶损伤。Duration-dry ( DD ) 对复水后立即对枝条的所有荧光测量有总体负面影响，这种影响在复水后 24 小时在四个荧光测量中的三个（F _m，F _v / F _m，Φ _PSII）中消散）。叶片损伤不受 Duration-dry 的影响。尽管未检测到预水化和持续干燥处理之间的相互作用，但当枝条暴露于更长的干燥期时，根据荧光指标F _v / F _m和 Φ _PSII，预水化的好处得到了加强。

结论。

在用液态水水化之前实施的预水化处理显着减轻了先前快速干燥事件和42% RH 下长达 50 天的DD产生的枝条损伤。基于光合效率，预水化在更长的DD 下产生更大的效果。在雨水之前经历潮湿的环境可以减轻长时间干燥造成的损害。