Root system architecture (RSA) plays an important role in soil water uptake and plant growth. However, there is a lack of understanding regarding the connection between the changes in RSA characteristics under drought stress in cotton plants and their drought tolerance and yield. This study aims to evaluate the RSA variations in different drought-tolerant cotton cultivars under drought stress, and to assess the correlation between RSA, drought tolerance, and yield. Three drought-tolerant cotton cultivars and three drought-sensitive cotton cultivars were grown in a field equipped with rain shelters to prevent interference from rainfall. Drought stress was initiated at the three-leaf stage, maintaining the soil relative water content at 50 ± 5%, while control plants were irrigated normally at 75 ± 5% soil water content. Multiple parameters, including leaf water potential, relative water content, seed cotton yield, and RSA traits, were assessed. Notable variations in drought tolerance were observed among different cultivars when exposed to drought stress. Specifically, drought-tolerant cultivars exhibited a 34% increase in the average length of all lateral roots and a 15% increase in maximum root depth under drought stress. In contrast, seed cotton yield experienced a reduction of 22.34% in such conditions. Interestingly, there were significant differences in several RSA traits under drought stress, which were not evident under well-watered. Leaf water potential and relative water content were positively correlated with specific root length, dry root weight, average length of all lateral roots and maximum depth, and negatively correlated with average lateral root emergence angle and width/depth ratio. These results underscore the close association between RSA traits and plant drought tolerance. There was also a strong correlation between the seed cotton yield and RSA traits. Specifically, seed cotton yield increased linearly with specific root length, average lengths of lateral roots, and maximum depth, but decreased linearly with root tissue density, and average lateral root emergence angle and width/depth ratio. Optimizing RSA improves drought tolerance and reduces yield loss in drought-tolerant cotton cultivars. Understanding of the role of RSA in plant adaptation to drought stress is important for selecting and developing high-yielding cultivars with superior drought tolerance. This knowledge holds great significance in improving cotton resilience and facilitating adapting to abiotic stress through genetic improvement or agronomic measures.

中文翻译：

---

优化根系结构以提高棉花的耐旱性并最大限度地减少轻度干旱胁迫期间的产量损失

根系结构（RSA）在土壤水分吸收和植物生长中发挥着重要作用。然而，对于干旱胁迫下棉花植株RSA特性的变化与其耐旱性和产量之间的关系还缺乏了解。本研究旨在评估不同耐旱棉花品种在干旱胁迫下RSA的变化，并评估RSA与耐旱性和产量之间的相关性。在配备避雨棚以防止降雨干扰的田地中种植了三个耐旱棉花品种和三个干旱敏感棉花品种。干旱胁迫在三叶期开始，保持土壤相对含水量在50±5%，而对照植物在75±5%土壤含水量下正常灌溉。评估了多个参数，包括叶片水势、相对含水量、籽棉产量和 RSA 性状。当暴露于干旱胁迫时，不同品种的耐旱性存在显着差异。具体而言，耐旱品种在干旱胁迫下所有侧根的平均长度增加了 34%，最大根深度增加了 15%。相比之下，籽棉产量下降了22.34%。有趣的是，在干旱胁迫下，一些 RSA 性状存在显着差异，而在浇水良好的情况下则不明显。叶水势和相对含水量与比根长、干根重、所有侧根平均长度和最大深度呈正相关，与平均侧根出苗角度和宽深比呈负相关。这些结果强调了 RSA 性状与植物耐旱性之间的密切联系。籽棉产量和 RSA 性状之间也存在很强的相关性。具体而言，籽棉产量随比根长度、平均侧根长度和最大深度线性增加，但随根组织密度、平均侧根出苗角和宽深比线性降低。优化 RSA 可提高耐旱棉花品种的耐旱性并减少产量损失。了解RSA在植物适应干旱胁迫中的作用对于选择和开发具有优异耐旱性的高产品种非常重要。这些知识对于通过遗传改良或农艺措施提高棉花的恢复力和促进适应非生物胁迫具有重要意义。