Sugarbeets are largely produced without irrigation, making drought stress inevitable when rainfall is insufficient. Whether drought stress impacts root storage, however, is currently unknown. Research was conducted to determine the effect of preharvest water stress on postharvest sugarbeet root respiration rate and susceptibility to storage rots as these traits are the primary determinants for sucrose loss and quality deterioration. Greenhouse‐grown plants were subjected to four levels of water deficit by discontinuing watering for 0, 7, 14 or 21 days prior to harvest. Plants receiving water‐restrictive treatments displayed physiological stress by leaf epinasty, reductions in net photosynthetic rate and leaf relative water content and increases in leaf temperature, whereas the water content of roots harvested from these plants progressively decreased with the severity of the preharvest water‐deficit treatment. Harvested roots from all watering treatments were stored at 10°C and 95% relative humidity for up to 12 weeks and evaluated for respiration rate and susceptibility to storage rot. Root respiration rate during storage was inversely related to root water content at harvest by second‐order equations, such that respiration was not significantly affected by minor reductions in root water content but increased exponentially for roots obtained from severely drought‐stressed plants with water contents at harvest of ≤75%. Similarly, roots with water contents ≤75% had elevated levels of electrolyte leakage, a measure of cellular membrane damage, and were more susceptible to dehydration and fungal infection during storage. In separate experiments, roots harvested from water‐stressed plants were inoculated with Botrytis cinerea or Penicillium vulpinum, two causal agents for storage rots. In these experiments, preharvest water stress quantitatively increased root rot and qualitatively altered symptoms of their infection. Overall, these results demonstrate that severe preharvest drought stress is likely to significantly increase sugarbeet root storage losses caused by root respiration and storage rots and that storage losses are likely to accelerate with time in storage. However, mild‐to‐moderate drought conditions prior to harvest are expected to have no or minimal effect on storage losses from root respiration or storage rots.

中文翻译：

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严重的采前干旱会加剧采后甜菜根的呼吸和贮藏腐烂


甜菜的生产大部分不需要灌溉，因此当降雨不足时，干旱胁迫不可避免。然而，干旱胁迫是否影响根系储存目前尚不清楚。进行研究以确定收获前水分胁迫对收获后甜菜根系呼吸速率和对储存腐烂的敏感性的影响，因为这些性状是蔗糖损失和品质恶化的主要决定因素。通过在收获前 0、7、14 或 21 天停止浇水，温室种植的植物会遭受四种程度的缺水。接受限水处理的植物表现出叶片上侧的生理应激、净光合速率和叶片相对含水量的降低以及叶片温度的升高，而从这些植物收获的根部的含水量随着收获前缺水的严重程度而逐渐降低治疗。将所有浇水处理收获的根在 10°C 和 95% 相对湿度下储存长达 12 周，并评估呼吸速率和对储存腐烂的敏感性。通过二阶方程，储存期间的根系呼吸速率与收获时的根系含水量成反比，因此，根系含水量的轻微降低不会显着影响呼吸作用，但对于从严重干旱胁迫的植物中获得的根系，其含水量为收获率≤75%。同样，含水量≤75%的根部电解质渗漏水平升高（细胞膜损伤的衡量标准），并且在储存过程中更容易脱水和真菌感染。 在单独的实验中，从缺水植物中收获的根部接种了灰葡萄孢（Botrytis cinerea）或狐青霉（Penicillium v​​ulpinum），这是两种引起贮藏腐烂的病原体。在这些实验中，收获前的水分胁迫在数量上增加了根腐病，并在质量上改变了感染症状。总体而言，这些结果表明，严重的收获前干旱胁迫可能会显着增加由根呼吸和贮藏腐烂引起的甜菜根贮藏损失，并且贮藏损失可能会随着贮藏时间的延长而加速。然而，收获前的轻度至中度干旱条件预计对根系呼吸或贮藏腐烂引起的贮藏损失没有影响或影响很小。