Center Agriculture Food Environment (C3A), University of Trento, via Mach 1, San Michele all'Adige, TN, 38098, Italy.
Research and Innovation Centre, Fondazione Edmund Mach, via Mach 1, San Michele all'Adige, TN, 38098, Italy.
Physiol Plant. 2023 Mar;175(2):e13906. doi: 10.1111/ppl.13906.
Transpiration per unit of leaf area is the end-product of the root-to-leaf water transport within the plant, and it is regulated by a series of morpho-physiological resistances and hierarchical signals. The rate of water transpired sustains a series of processes such as nutrient absorption and leaf evaporative cooling, with stomata being the end-valves that maintain the optimal water loss under specific degrees of evaporative demand and soil moisture conditions. Previous work provided evidence of a partial modulation of water flux following nitrogen availability linking high nitrate availability with tight stomatal control of transpiration in several species. In this work, we tested the hypothesis that stomatal control of transpiration, among others signals, is partially modulated by soil nitrate ( ) availability in grapevine, with reduced availability (alkaline soil pH, reduced fertilization, and distancing source) associated with decreased water-use efficiency and higher transpiration. We observed a general trend when was limiting with plants increasing either stomatal conductance or root-shoot ratio in four independent experiments with strong associations between leaf water status, stomatal behavior, root aquaporins expression, and xylem sap pH. Carbon and oxygen isotopic signatures confirm the proximal measurements, suggesting the robustness of the signal that persists over weeks and under different gradients of availability and leaf nitrogen content. Nighttime stomatal conductance was unaffected by manipulation treatments, while application of high vapor pressure deficit conditions nullifies the differences between treatments. Genotypic variation for transpiration increase under limited availability was observed between rootstocks indicating that breeding (e.g., for high soil pH tolerance) unintentionally selected for enhanced mass flow nutrient acquisition under restrictive or nutrient-buffered conditions. We provide evidence of a series of specific traits modulated by availability and suggest that fertilization is a potential candidate for optimizing grapevine water-use efficiency and root exploration under the climate-change scenario.
单位叶面积蒸腾量是植物根系到叶片内水分运输的最终产物，它受到一系列形态生理阻力和层次信号的调节。蒸腾速率维持着一系列过程，如养分吸收和叶片蒸发冷却，而气孔是在特定蒸发需求和土壤水分条件下维持最佳水分损失的终末阀门。先前的工作提供了证据表明，氮素供应会部分调节水分通量，高硝酸盐供应与几种物种中蒸腾的紧密气孔控制有关。在这项工作中，我们检验了以下假设：除其他信号外，气孔对蒸腾的控制在葡萄中也部分受到土壤硝酸盐（ ）可用性的调节，减少 可用性（碱性土壤 pH 值、减少施肥和远离氮源）与降低水分利用效率和增加蒸腾有关。当 受到限制时，我们观察到了一个普遍趋势，植物通过增加气孔导度或根冠比来适应，这在四个独立的实验中得到了证实，其中叶片水分状况、气孔行为、根系 aquaporin 表达和木质部汁液 pH 值之间存在强烈关联。碳和氧同位素特征证实了近端测量，表明该信号具有稳健性，可在数周内持续存在，并在不同的 可用性和叶片氮含量梯度下保持不变。夜间气孔导度不受 处理的影响，而高蒸气压亏缺条件的应用则消除了处理之间的差异。在受限制的 可用性下，砧木之间观察到蒸腾增加的基因型变异，这表明在限制或营养缓冲条件下，通过选育（例如，对高土壤 pH 值的耐受性）无意中选择了增强的质量流养分获取。我们提供了一系列受 可用性调节的特定特征的证据，并表明 施肥是优化葡萄水分利用效率和根系探索的潜在候选方案。
