This article presents findings from a field research study conducted in the San Joaquin Valley of California in 2016–2018 to appraise the effects of soil salinity and sodicity on evapotranspiration and energy balance components of micro-irrigated pistachio orchards. Actual evapotranspiration (ETa) and tree physiologic parameters were measured during consecutive growing seasons in mature orchards grown on non-saline and saline/sodic soils. Salinity and sodicity decreased pistachio water use by about 30%, with ETa reductions varying along the growing season. Accurate information on the dynamics of ETa and energy balance components along the growing season can improve water management for nut orchards exposed to long-term saline-sodic conditions. Results show that the main driver of ETa was the net radiation (Rn), which supplied most of the energy to vaporize water, irrespective of the growth period and level of salinity/sodicity. Field observations revealed that Rn was lower for salt-affected trees due to smaller canopies, which intercepted less light than non-saline trees. Secondarily, the exchange of sensible heat (H) between the ambient air and tree canopies was affected by the interaction between salinity–sodicity and seasonality. Early in the season, salinity and sodicity affected ETa mainly through the reduced canopy growth, which decreased the available energy (Rn–G) for ETa and reduced the water uptake as a result of the lower soil water potential. Late in the season, an increase in H and a decrease in the contribution of the aerodynamic component (β coefficient) to the latent heat flux (LE) occurred, which determined a further reduction of ETa due to a physiological response. The decrease in the β coefficient during the late season was associated with a direct impact of ion accumulation on leaf functionality. Collecting data on the contribution of the aerodynamic component to LE offers a low-cost method to detect and quantify physiological stress, while providing useful information for managing irrigation in salt-affected orchards. The results presented in this article provide insights to improve irrigation management of salt-affected pistachio through integration of weather measurements, energy balance components, and plant-based parameters.

中文翻译：

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盐度和碱度对成熟微灌开心果园实际蒸散量季节动态和表面能平衡成分的影响

本文介绍了 2016 年至 2018 年在加利福尼亚州圣华金河谷进行的实地研究的结果，以评估土壤盐度和碱度对微灌开心果园蒸散和能量平衡成分的影响。在非盐分和盐分/钠盐土壤上生长的成熟果园中，在连续生长季节期间测量实际蒸散量 (ETa) 和树木生理参数。盐度和碱度使开心果用水量减少了约 30%，ETa 减少量随生长季节而变化。关于 ETa 动态和生长季节能量平衡成分的准确信息可以改善长期暴露在盐碱条件下的坚果园的水分管理。结果表明，ETa 的主要驱动因素是净辐射 (Rn)，无论生长期和盐度/碱度如何，它都提供了大部分能量来蒸发水。实地观察表明，受盐分影响的树木的 Rn 较低，因为树冠较小，比非盐分树木拦截的光线更少。其次，环境空气和树冠之间的显热 (H) 交换受盐度-碱度和季节性之间的相互作用的影响。在季节早期，盐度和碱度主要通过减少冠层生长来影响 ETa，这降低了 ETa 的可用能量 (Rn-G) 并由于较低的土壤水势而减少了吸水量。在季节后期，H 增加，空气动力分量（β 系数）对潜热通量（LE）的贡献减少，这确定了由于生理反应导致的 ETa 进一步减少。后期β系数的降低与离子积累对叶片功能的直接影响有关。收集空气动力学组件对 LE 的贡献的数据提供了一种检测和量化生理压力的低成本方法，同时为管理受盐分影响的果园灌溉提供了有用的信息。本文中的结果提供了见解，通过整合天气测量、能量平衡组件和基于植物的参数来改善受盐影响的开心果的灌溉管理。收集空气动力学组件对 LE 的贡献的数据提供了一种检测和量化生理压力的低成本方法，同时为管理受盐分影响的果园灌溉提供了有用的信息。本文中的结果提供了见解，通过整合天气测量、能量平衡组件和基于植物的参数来改善受盐影响的开心果的灌溉管理。收集空气动力学组件对 LE 的贡献的数据提供了一种检测和量化生理压力的低成本方法，同时为管理受盐分影响的果园灌溉提供了有用的信息。本文中的结果提供了见解，通过整合天气测量、能量平衡组件和基于植物的参数来改善受盐影响的开心果的灌溉管理。