Sustainable irrigation based on co-regulation of soil water supply and atmospheric evaporative demand.

Irrigation is an important adaptation to reduce crop yield loss due to water stress from both soil water deficit (low soil moisture) and atmospheric aridity (high vapor pressure deficit, VPD). Traditionally, irrigation has primarily focused on soil water deficit. Observational evidence demonstrates that stomatal conductance is co-regulated by soil moisture and VPD from water supply and demand aspects.

Seasonal responses of photosynthetic parameters in maize and sunflower and their relationship with leaf functional traits.

Estimates of seasonal variation in photosynthetic capacity (P ) are critical for modeling the time course of carbon fluxes. Given the time-intensive nature of calculating P parameters via gas exchange, it is appealing to calculate parameter variation via changes in chlorophyll (Chl) and nitrogen (N) content by assuming that P scales with these variables. Although seasonal changes in P and the relationships between N and P have been evaluated in forest canopies, there is limited data on seasonal parameter values in crops, nor is it clear if seasonal changes in P can be estimated from leaf traits under the high N fertility of managed systems.

Seasonal variability of the parameters of the Ball-Berry model of stomatal conductance in maize (Zea mays L.) and sunflower (Helianthus annuus L.) under well-watered and water-stressed conditions.

The Ball-Berry (BB) model of stomatal conductance (g ) is frequently coupled with a model of assimilation to estimate water and carbon exchanges in plant canopies. The empirical slope (m) and 'residual' g (g ) parameters of the BB model influence transpiration estimates, but the time-intensive nature of measurement limits species-specific data on seasonal and stress responses. We measured m and g seasonally and under different water availability for maize and sunflower.

Estimating the sensitivity of stomatal conductance to photosynthesis: a review.

A common approach for estimating fluxes of CO and water in canopy models is to couple a model of photosynthesis (A ) to a semi-empirical model of stomatal conductance (g ) such as the widely validated and utilized Ball-Berry (BB) model. This coupling provides an effective way of predicting transpiration at multiple scales. However, the designated value of the slope parameter (m) in the BB model impacts transpiration estimates.