Abdalla Mohanned, Schweiger Andreas H, Berauer Bernd J, McAdam Scott A M, Ahmed Mutez Ali
Department of Land, Air and Water Resources, University of California Davis, Davis, CA, United States.
Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.
Front Plant Sci. 2023 Mar 17;14:1140938. doi: 10.3389/fpls.2023.1140938. eCollection 2023.
Carbon-water trade-offs in plants are adjusted through stomatal regulation. Stomatal opening enables carbon uptake and plant growth, whereas plants circumvent drought by closing stomata. The specific effects of leaf position and age on stomatal behavior remain largely unknown, especially under edaphic and atmospheric drought. Here, we compared stomatal conductance ( ) across the canopy of tomato during soil drying. We measured gas exchange, foliage ABA level and soil-plant hydraulics under increasing vapor pressure deficit (). Our results indicate a strong effect of canopy position on stomatal behavior, especially under hydrated soil conditions and relatively low . In wet soil (soil water potential > -50 kPa), upper canopy leaves had the highest (0.727 ± 0.154 mol m s) and assimilation rate (; 23.4 ± 3.9 µmol m s) compared to the leaves at a medium height of the canopy ( : 0.159 ± 0.060 mol m s; : 15.9 ± 3.8 µmol m s). Under increasing (from 1.8 to 2.6 kPa), , and transpiration were initially impacted by leaf position rather than leaf age. However, under high (2.6 kPa), age effect outweighed position effect. The soil-leaf hydraulic conductance was similar in all leaves. Foliage ABA levels increased with rising in mature leaves at medium height (217.56 ± 85 ng g FW) compared to upper canopy leaves (85.36 ± 34 ng g FW). Under soil drought (< -50 kPa), stomata closed in all leaves resulting in no differences in across the canopy. We conclude that constant hydraulic supply and ABA dynamics facilitate preferential stomatal behavior and carbon-water trade-offs across the canopy. These findings are fundamental in understanding variations within the canopy, which helps in engineering future crops, especially in the face of climate change.
植物中的碳 - 水权衡通过气孔调节来调整。气孔开放促进碳吸收和植物生长，而植物通过关闭气孔来规避干旱。叶片位置和年龄对气孔行为的具体影响在很大程度上仍不清楚，尤其是在土壤和大气干旱条件下。在这里，我们比较了土壤干燥过程中番茄冠层不同位置的气孔导度（ ）。我们在不断增加的蒸汽压亏缺（ ）下测量了气体交换、叶片脱落酸水平和土壤 - 植物水力状况。我们的结果表明冠层位置对气孔行为有强烈影响，尤其是在土壤水分充足和相对较低的 条件下。在湿润土壤（土壤水势 > -50 kPa）中，与冠层中部高度的叶片相比，冠层上部叶片具有最高的 （0.727 ± 0.154 mol m² s⁻¹）和同化速率（ ；23.4 ± 3.9 µmol m² s⁻¹）。冠层中部高度叶片的 为0.159 ± 0.060 mol m² s⁻¹， 为15.9 ± 3.8 µmol m² s⁻¹。在 增加（从1.8到2.6 kPa）时， 、 和蒸腾作用最初受叶片位置而非叶片年龄的影响。然而，在高 （2.6 kPa）下，年龄效应超过了位置效应。所有叶片的土壤 - 叶片水力导度相似。与冠层上部叶片（85.36 ± 34 ng g⁻¹ FW）相比，冠层中部高度成熟叶片中的叶片脱落酸水平随 升高而增加（217.56 ± 85 ng g⁻¹ FW）。在土壤干旱（ < -50 kPa）下，所有叶片的气孔关闭，导致整个冠层的 没有差异。我们得出结论，持续的水力供应和脱落酸动态变化促进了冠层内优先的气孔行为和碳 - 水权衡。这些发现对于理解冠层内的变化至关重要，这有助于设计未来的作物，尤其是在面对气候变化的情况下。
