Department of Civil and Environmental Engineering, Portland State University, Portland, OR, USA.
Stantec, New York, NY, USA.
Plant Cell Environ. 2021 Jan;44(1):34-48. doi: 10.1111/pce.13918. Epub 2020 Oct 31.
Crassulacean acid metabolism (CAM) crops are important agricultural commodities in water-limited environments across the globe, yet modelling of CAM productivity lacks the sophistication of widely used C3 and C4 crop models, in part due to the complex responses of the CAM cycle to environmental conditions. This work builds on recent advances in CAM modelling to provide a framework for estimating CAM biomass yield and water use efficiency from basic principles. These advances, which integrate the CAM circadian rhythm with established models of carbon fixation, stomatal conductance and the soil-plant-atmosphere continuum, are coupled to models of light attenuation, plant respiration and biomass partitioning. Resulting biomass yield and transpiration for Opuntia ficus-indica and Agave tequilana are validated against field data and compared with predictions of CAM productivity obtained using the empirically based environmental productivity index. By representing regulation of the circadian state as a nonlinear oscillator, the modelling approach captures the diurnal dynamics of CAM stomatal conductance, allowing the prediction of CAM transpiration and water use efficiency for the first time at the plot scale. This approach may improve estimates of CAM productivity under light-limiting conditions when compared with previous methods.
景天酸代谢（CAM）作物在全球水资源有限的环境中是重要的农业商品，但 CAM 生产力的建模缺乏广泛使用的 C3 和 C4 作物模型的精细程度，部分原因是 CAM 循环对环境条件的复杂反应。这项工作基于 CAM 建模的最新进展，从基本原理出发，为估计 CAM 生物量产量和水分利用效率提供了一个框架。这些进展将 CAM 昼夜节律与已建立的碳固定、气孔导度和土壤-植物-大气连续体模型相结合，并与光衰减、植物呼吸和生物量分配模型相结合。针对仙人掌和龙舌兰的生物量产量和蒸腾作用进行了验证，并与使用基于经验的环境生产力指数获得的 CAM 生产力预测进行了比较。通过将昼夜节律状态的调节表示为非线性振荡器，该建模方法捕获了 CAM 气孔导度的日动态，首次能够在田间尺度上预测 CAM 蒸腾作用和水分利用效率。与以前的方法相比，这种方法可能会提高在光限制条件下对 CAM 生产力的估计。
