Plantarray是一款基于称重的高通量、多传感器生理表型平台以及植物逆境生物学研究通用平台。 该系统可持续、实时测量位于不同环境条件下、阵列中每个植株的土壤-植物-空气（SPAC）中的即时水流动。 直接测量根系和茎叶系统水平衡和生物量增加，计算植物生理参数以及植物对动态环境的反馈。 系统以有效、易用、无损的方式针对植物对不同处理的反应、预测植物生长和生产力进行定量比较，广泛应用于生物胁迫和非生物胁迫以及植物栽培加速育种研究等，胁迫研究涵盖干旱胁迫、盐胁迫、重金属胁迫、热、冷胁迫、光胁迫以及灌溉/养分、CO2指示、植物健康等领域的研究。

培育抗旱作物需要了解植物对不同干旱模式的生理反应机制，以及这些反应在物种内是如何变化的。文献中区分了两种主要的植物用水策略，称为“冒险”（异水性）和“保存”（等水性）。在水分充足的条件下，与气孔控制更严格的保护植物相比，冒险者表现出更高的蒸腾速率（TR），这与更高的CO2同化速率有关，因此干物质产量更高。根据根系特征，具有相似地上部特征的植物之间的蒸腾极限土壤水分水平（θcrit）可能不同。高θcrit（例如，由于浅根）导致气孔提前闭合。本研究旨在检验四个被认为表现出不同反应行为的高产欧洲春大麦品种的干旱反应。

我们使用高通量功能表型平台（Plantrarray®，plant Ditech）收集了详细的植物生理数据，并分析了最终的产量参数。在开花前后，Chanelle（CHAN）、RGT Planet（RGT）、Formula（FORM）和Baroness（BAR）遭受了12天的干旱。基于较高的TR、较高的生物量和粮食产量，以及在水分充足的条件下更快的TR降低到θcrit以下，与保存FORM和非常保存BAR相比，CHAN被列为非常冒险，RGT被列为冒风险。

干旱对最终产量的影响与植物恢复潜力密切相关，即在重新灌溉时增加TR以控制植物水平的能力。在充足的供水条件下，产量最高的品种CHAN表现出显著的恢复潜力受损，并在干旱条件下遭受显著的产量损失（24%）。BAR非常保守的响应行为导致了良好的回收率、最小的产量损失（-2%的产量）和几乎与非常冒险的CHAN（Δ5g/盆）相似的最终谷物产量。在控制和胁迫条件下，FORM的产量最低，但没有受到干旱引起的产量损失，这可能是由于根系更适应。FORM较低的θ标准延迟了气孔闭合和同化作用的破坏。FORM和RGT的回收率相似。

RGT在水分充足的条件下产量排第二，干旱没有造成任何产量损失。在充足的供水条件下，RGT表现得像一个冒险者，因此高TR使其比保护品种更有生产力。在干旱条件下，RGT转变为更具保护性的行为，它只是逐渐（与FORM相同的斜率）将TR降低到θcrit以下，因此比非常冒险的CHAN更具生产力。这种相当动态的用水行为使RGT成为在这里检查的干旱情况下表现最好的品种。

在干旱条件下观察到的FORM和RGT中，每穗种子数量的增加（以及粒径的减小）可能有助于产量的稳定，其确切的生理机制仍需要更多的研究。前瞻性研究将检查不同的干旱模式和持续时间，并将所获得的知识应用到作物模拟模型中，以扩大规模。

关键词：水反应行为，等氢；各向异性；春大麦、干旱

Drought response behavior of risk-taking  and conserving spring barley cultivars

Breeding drought resilient  crops requires  understanding the mechanisms underlying  plant physiological responses to different drought patterns and how these vary within species.Two main plant water use strategies are distinguished in the literature, referred to as “risk – taking” (anisohydric)  and “conserving”  (isohydric).  Under  well-watered conditions,  risk takers  exhibit  a higher transpiration rate (TR) associated with a greater CO2 assimilation  rate, and hence, greater dry matter production than conserving plants which have a tighter stomatal control. Depending on the root  traits  the transpiration-limiting soil moisture level (θcrit) can differ  between  plants  with similar shoot traits. A high θcrit (e.g. due to shallow roots) entails early stomata closure. This study aimed at examining  the drought response of four  high-yielding European spring barley cultivars considered to exhibit different response behavior.

We collected  detailed  plant  physiological  data with  a high- throughput functional phenotyping platform (Plantarray®,  Plant-Ditech)  and analyzed final  yield parameters.  Around  flowering  cv. Chanelle (CHAN), RGT Planet (RGT), Formula (FORM), and Baroness (BAR) were exposed to 12 days of drought.  Based on higher TR, higher biomass and grain yield under well-watered conditions and the faster  TR reduction below  θcrit,CHAN ranked  as very risk taking  and RGT as risk taking  in contrast to conserving FORM and very conserving BAR.

Drought  effects on final yield are closely linked to the plants recovery potential,  i.e. the ability to increase TR to control  plant  levels upon  re-irrigation. The highest  yielding  cultivar  under  ample water supply, CHAN, showed a significantly impaired recovery potential and suffered notable yield penalties  under  drought (24%). The very conserving response behavior  of BAR resulted  in good recovery, minimal yield loss (-2% yield) and a final grain yield that was almost similar to very risk taking CHAN (Δ 5g/pot). FORM produced  the lowest yields under control  and stress conditions  yet suffered  no drought induced yield penalties, probably  due to a better  adapted root  system. The lower θcritof  FORM delayed stomata  closure and the breakdown of assimilation.  FORM and RGT had similar recovery rates.

RGT produced  the second highest yield under well-watered conditions  and drought did not cause any yield losses. Under ample water supply, RGT behaved like a risk taker, whereby  the high TR allowed it to be more productive than the conserving cultivars. RGT switched to a more conserving behavior  under  drought where it only gradually  (same slope as FORM) decreased TR below θcrit and was thereby  more  productive than  very risk taking  CHAN. This rather  dynamic  water  use behavior made RGT the best performing cultivar in the here examined drought scenario.

A higher number of seeds per spike (along with reduced kernel size) likely contributed to the yield stability  observed under drought in FORM and RGT the exact physiological mechanisms of which still require  more investigation. Prospective studies will examine different drought patterns  and durations and implement the gained knowledge into crop simulation models for upscaling.

Keywords: water-response behavior, isohydric; anisohydric; spring barley,drought