When water resources are limited, cotton (Gossypium hirsutum L.) plants adapt in part through adjustments in carbon allocation strategies, often evident in the leaves within the canopy. The dynamics of leaf carbon accumulation provide insights into how the plant partitions and uses carbon resources, a key aspect of optimizing crop productivity. In this study, we investigated the dynamics of leaf carbon accumulation in two cotton cultivars (Phytogen [PHY] 350 and Stoneville [ST] 5707) across spatial and temporal scales under two different levels of irrigation (low: 178 mm year⁻¹, high: 356 mm year⁻¹) in 2020 and 2021. For each cultivar and irrigation treatment, an increase in leaf mass occurred primarily at the bottom of the canopy early in the season, followed by additional leaf production in the middle of the plant as the season progressed. Irrigation reduction resulted in a canopy with reduced radiation interception, less leaf shading in the lower canopy, and thicker leaves. In contrast, more irrigation created canopies with a larger effective leaf area, increasing total light interception despite increased shading at the canopy base. Additionally, leaf carbon allocation is synchronized with fruit carbon demand at the onset of the first bloom stage for an early-maturing cultivar. Overall, this study provides valuable insights into the complex relationship between water availability, radiation intensity within the canopy, and leaf carbon dynamics, contributing to a more comprehensive understanding of the plant's overall performance in resource-constrained environments.

中文翻译：

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树冠内碳分配响应灌溉而与棉花叶片


当水资源有限时，棉花 （Gossypium hirsutum L.） 植物部分通过调整碳分配策略来适应，这在树冠内的叶子中通常很明显。叶片碳积累的动力学提供了关于植物如何分配和利用碳资源的见解，这是优化作物生产力的一个关键方面。在这项研究中，我们研究了 2020 年和 2021 年两种不同灌溉水平（低温：178 毫米年^-1，高：356 毫米年^-1）下两个棉花品种（Phytogen [PHY] 350 和 Stoneville [ST] 5707）在空间和时间尺度上的叶片碳积累动态。对于每个栽培品种和灌溉处理，叶量的增加主要发生在季节早期的树冠底部，然后随着季节的进行，植物中期的叶子产量增加。减少灌溉导致树冠的辐射拦截减少，下树冠的叶子阴影减少，叶子更厚。相比之下，更多的灌溉创造了具有更大有效叶面积的树冠，尽管树冠基部的阴影增加了，但增加了总光拦截。此外，对于早熟品种，叶片碳分配与初开花阶段开始时的果实碳需求同步。总体而言，这项研究为水的可用性、冠层内的辐射强度和叶片碳动力学之间的复杂关系提供了有价值的见解，有助于更全面地了解植物在资源受限环境中的整体性能。