In wheat and barley, grain yield is strongly affected by waterlogging, especially during the period immediately previous to anthesis. Although waterlogging reduces grain yield mainly by reductions in grain number, mean grain weight (MGW) is also frequently reduced. The aim of this work was to determine whether increases in the source-sink ratio produces smaller reductions in MGW due to waterlogging in wheat and barley. Two experiments were carried out combining a waterlogging condition 20 days pre-anthesis, two soil N conditions at sowing and source-sink manipulations during grain-filling (untrimmed or 50% trimmed spikes). Waterlogging reduced MGW in both species up to 35% in wheat and 44% in barley. The negative effect of waterlogging on MGW was intensified with warmer temperatures and higher atmospheric demand. Increases in the source-sink ratio during the grain-filling period (by trimming treatments) showed a positive impact on MGW in wheat (up to 40%) and barley (up to 20%) under waterlogging conditions. For both species, grain weight response to increases in source-sink ratio was higher at lower grain weight and/or spike hierarchies (i.e. spikes from tillers). Our results showed that waterlogging during pre-anthesis affected grain weight through a reduction in the source during grain-filling and a possible impact on potential grain weight, depending on the intensity of the stress.

中文翻译：

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涝渍条件下小麦和大麦开花前粒重的源库限制

在小麦和大麦中，粮食产量受涝渍的影响很大，尤其是在开花前的时期。虽然涝渍主要通过减少粒数来降低粮食产量，但平均粒重（MGW）也经常降低。这项工作的目的是确定由于小麦和大麦的涝渍，源库比的增加是否会产生较小的 MGW 减少。结合开花前 20 天的涝渍条件、播种时的两种土壤 N 条件和灌浆期间的源库操作（未修剪或修剪 50% 的穗状花序）进行了两个实验。涝渍使小麦和大麦这两个品种的 MGW 降低了 35% 和 44%。随着气温升高和大气需求增加，内涝对 MGW 的负面影响加剧。灌浆期源库比的增加（通过修剪处理）对涝渍条件下小麦（高达 40%）和大麦（高达 20%）的 MGW 有积极影响。对于这两个物种，粒重对源库比增加的响应在较低的粒重和/或穗等级（即分蘖的穗）下较高。我们的研究结果表明，开花前的涝渍通过减少灌浆过程中的水源来影响粒重，并可能影响潜在的粒重，具体取决于压力的强度。粒重对源库比增加的响应在较低粒重和/或穗层级（即来自分蘖的穗）下较高。我们的研究结果表明，开花前的涝渍通过减少灌浆过程中的水源来影响粒重，并可能影响潜在的粒重，具体取决于压力的强度。粒重对源库比增加的响应在较低粒重和/或穗层级（即来自分蘖的穗）下较高。我们的研究结果表明，开花前的涝渍通过减少灌浆过程中的水源来影响粒重，并可能影响潜在的粒重，具体取决于压力的强度。