Root morphology and anatomy are important plant traits that could potentially influence seedling vigour, resource acquisition and susceptibility to early-season stress. Therefore, the objective of the current experiment was to evaluate the effects of cultivar and growth temperature on seedling root growth and anatomical characteristics in cotton. To address this objective, experiments were conducted with six modern cotton cultivars, expected to have differences in seedling vigour, grown under optimal (30/20°C) and suboptimal (20/15°C) day/night temperature regimes. Root morphology and taproot cross-sectional anatomy were evaluated two weeks after planting. Cultivars with the most vigorously growing root systems produced 73% more secondary roots, 68% more total root length, 74% more surface area and 72% higher total root volume than the least vigorous cultivars. The cultivar with the greatest production of secondary roots also exhibited a somewhat uncommon hexarch arrangement of vascular bundles in taproot cross sections. Thus, we suggest that this difference in root anatomy may be a determinant of genotypic differences in lateral root development. In response to low temperature, taproot length, total root length, secondary root formation, root surface area and root volume declined substantially relative to optimal temperature conditions (35%–75% declines). This reinforces the need to ensure optimal temperature conditions at planting or to identify cultivars with improved performance under suboptimal early-season conditions. Conversely, root diameter responded positively to low growth temperatures, and cold-induced increases in root thickness were associated with increases in the number and cross-sectional area of root cells.

中文翻译：

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次优温度下棉花幼苗根系生长及解剖

根的形态和解剖学是重要的植物性状，可能会影响幼苗活力、资源获取和对早季胁迫的敏感性。因此，本实验的目的是评估品种和生长温度对棉花幼苗根系生长和解剖特征的影响。为了实现这一目标，对六种现代棉花品种进行了实验，这些品种预计在幼苗活力方面存在差异，在最佳 (30/20°C) 和次佳 (20/15°C) 日/夜温度条件下生长。种植后两周评估根形态和主根横截面解剖结构。根系生长最旺盛的品种产生的次生根增加了 73%，总根长增加了 68%，与最不旺盛的品种相比，表面积增加 74%，总根体积增加 72%。次生根产量最高的品种在主根横截面中也表现出不常见的维管束六角排列。因此，我们认为这种根解剖结构的差异可能是侧根发育基因型差异的决定因素。响应低温，主根长度、总根长度、次生根形成、根表面积和根体积相对于最佳温度条件显着下降（下降 35%–75%）。这加强了确保种植时的最佳温度条件或确定在次优早季条件下具有改进性能的品种的必要性。相反，根直径对低生长温度有积极反应，