Drought stress restricts sugar beet growth and yield formation. For the development of adapted varieties, reasons for high water demand in certain growth periods and for genotypic differences in water use efficiency (WUE) were investigated. In 2019 and 2020, different drought stress periods were simulated in pot trials in the greenhouse with four sugar beet genotypes by reducing the water supply to 50% of the water holding capacity. With unlimited water supply, water consumption developed in parallel to the growth rate. This indicates that water demand is driven by growth rate. Therefore, early drought stress in the period with highest growth rate caused strongest yield reductions, which could not be compensated later in the season. Unlike sugar yield, water consumption differed among genotypes, resulting in genotypic differences in WUE. However, no relevant genotype by water supply interaction occurred, giving no indication for drought tolerance of the genotypes with high WUE. WUE is rather determined by the sugar yield potential of a genotype than by water supply. Therefore, sugar beet genotypes should be selected for their sugar yield potential when breeding for environments with varying water supply.

中文翻译：

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甜菜基因型的水分利用效率：生长速率与水分消耗之间的关系

干旱胁迫限制甜菜生长和产量形成。为了开发适应性品种，调查了某些生长时期高需水量和水分利用效率（WUE）的基因型差异的原因。2019年和2020年，通过将供水量减少至持水量的50%，在温室中用四种甜菜基因型进行盆栽试验，模拟了不同的干旱胁迫时期。在无限供水的情况下，用水量与增长率同步发展。这表明需水量是由增长率驱动的。因此，生长速度最快时期的早期干旱胁迫导致最强烈的减产，而这在季节后期无法得到补偿。与糖产量不同，基因型之间的耗水量不同，导致 WUE 的基因型差异。然而，没有发生与供水相互作用的相关基因型，没有表明具有高WUE的基因型具有耐旱性。WUE 是由基因型的糖产量潜力决定的，而不是由供水决定的。因此，在为不同供水环境进行育种时，应根据其产糖潜力选择甜菜基因型。