Department of Civil and Environmental Engineering and High Meadows Environmental Institute, Princeton University, Princeton, NJ, 08540, USA.
Department of Civil and Environmental Engineering, Duke University, Durham, NC, 27708, USA.
New Phytol. 2024 Oct;244(2):426-435. doi: 10.1111/nph.20035. Epub 2024 Aug 19.
Plant response to water stress involves multiple timescales. In the short term, stomatal adjustments optimize some fitness function commonly related to carbon uptake, while in the long term, traits including xylem resilience are adjusted. These optimizations are usually considered independently, the former involving stomatal aperture and the latter carbon allocation. However, short- and long-term adjustments are interdependent, as 'optimal' in the short term depends on traits set in the longer term. An economics framework is used to optimize long-term traits that impact short-term stomatal behavior. Two traits analyzed here are the resilience of xylem and the resilience of nonstomatal limitations (NSLs) to photosynthesis at low-water potentials. Results show that optimality requires xylem resilience to increase with climatic aridity. Results also suggest that the point at which xylem reach 50% conductance and the point at which NSLs reach 50% capacity are constrained to approximately a 2 : 1 linear ratio; however, this awaits further experimental verification. The model demonstrates how trait coordination arises mathematically, and it can be extended to many other traits that cross timescales. With further verification, these results could be used in plant modelling when information on plant traits is limited.
植物对水分胁迫的响应涉及多个时间尺度。在短期内，气孔调节优化了一些与碳吸收有关的适应值函数，而在长期内，包括木质部弹性在内的特征被调整。这些优化通常被独立考虑，前者涉及气孔开度，后者涉及碳分配。然而，短期和长期的调整是相互依存的，因为短期的“最优”取决于长期设定的特征。本文使用经济学框架来优化影响短期气孔行为的长期特征。这里分析的两个特征是木质部弹性和光合作用在低水分势下非气孔限制（NSLs）的弹性。结果表明，最优性要求木质部弹性随气候干旱度的增加而增加。结果还表明，木质部达到 50%导度的点和 NSL 达到 50%容量的点被约束在大约 2：1 的线性比例；然而，这需要进一步的实验验证。该模型展示了特征协调如何在数学上出现，并且它可以扩展到许多其他跨越时间尺度的特征。随着进一步的验证，当植物特征信息有限时，这些结果可以用于植物模型。
