Transpiration response to soil drying versus increasing vapor pressure deficit in crops: physical and physiological mechanisms and key plant traits

Abstract

The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit, VPD) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil-plant hydraulic framework. In both cases of drying, stomatal closure is triggered by limitations in soil-plant hydraulic conductance. However, traits impacting the transpiration response differ between the two drying processes and act at different time scales. A low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing VPD. During soil drying, the impact of the plant hydraulic conductance is less obvious. It is rather a decrease in the belowground hydraulic conductance (related to soil hydraulic properties and root length density) that is involved in transpiration downregulation. The transpiration response to increasing VPD has a daily time scale. In the case of soil drying, it acts on a seasonal scale. Varieties that are conservative in water use on a daily scale may not be conservative over larger time scales (e.g. during soil drying). This potential independency of strategies needs to be considered in environmental-specific breeding for yield-based drought tolerance.

Water Uptake by Mountain Big Sagebrush (Artemisia tridentata subsp. vaseyana) and Environmental Variables Affecting Water Availability in Semiarid Rangeland Ecosystems

“…Under low SM conditions, a decrease in VPD likely led to a decrease in stomatal conductance, thereby reducing sagebrush transpiration. This aligns with various studies investigating vegetation water use in response to low VPD and water availability [43][44][45]. Stomatal conductance helps minimize plant water loss [46].…”

The optimized Maxent model reveals the pattern of distribution and changes in the suitable cultivation areas for Reaumuria songarica being driven by climate change

“…Plants in arid and semi‐arid regions typically exhibit strong drought tolerance, yet water remains a crucial limiting factor for their growth and distribution (D'Odorico & Bhattachan, 2012 ; Wang et al., 2020 ). Precipitation influences various physiological processes and metabolic reactions in plants by regulating soil moisture, including carbon fixation (Matthews et al., 2017 ), transpiration (Koehler et al., 2023 ), photosynthesis (Oliver et al., 2023 ), and the synthesis of key metabolites (Herrera, 2009 ). Consequently, precipitation significantly impacts biomass accumulation, reproduction, and distribution of R. songarica .…”

“…The Precipitation influences various physiological processes and metabolic reactions in plants by regulating soil moisture, including carbon fixation (Matthews et al, 2017), transpiration (Koehler et al, 2023), photosynthesis (Oliver et al, 2023), and the synthesis of key metabolites (Herrera, 2009). Consequently, precipitation significantly impacts biomass accumulation, reproduction, and distribution of R. songarica.…”

The Advancement and Prospects of the Tree Trunk Injection Technique in the Prevention and Control of Diseases and Pests

“…According to the theory of hydraulic conductivity, plants absorb water and nutrients from underground and convert them into organic matter, which then moves into the vascular bundle through intercellular spaces. The movement of these substances is regulated by two pressures within the plant: root pressure generated at the root and vapor pressure created by transpiration in the aboveground leaves [28,29]. Transpiration in leaves leads to significant water loss, creating a negative pressure region between the leaves and the air.…”