Interrelationships between water use efficiency and light use efficiency in four row crop canopies

Abstract

Quantitative evidence of light use efficiency (LUE) controls on water use efficiency (WUE) is lacking, especially comparatively across row crops. Field research experiments (2016-2018) were set up for maize (Zea mays L.), soybean [Glycine max (L.) Merr.], sorghum [Sorghum bicolor (L.) Moench], and winter wheat (Triticum aestivum L.), under optimal growth conditions in dry sub-humid conditions. Overall, LUE was able to explain 52% of variance in WUE, and were related as WUE = 1.73 LUE, although crop-specific variation was observed. Highest sensitivity of WUE to changes in LUE was found in sorghum, followed by soybean, winter wheat, and maize. Evapotranspiration per unit light absorbed by crop canopy, which is a measure of canopy conductance (g c) ranged from a minimum of 0.45 kg H 2 O MJ −1 in sorghum to a maximum of 0.68 kg H 2 O MJ −1 in maize. Slopes of WUE vs. LUE relationship were limited by energy-limited upper ceiling of latent heat of vaporization and characterized distribution of absorbed energy into latent heat of vaporization and sensible heat. Vapor pressure deficit (VPD) accounted for 41% of variability in the WUE vs. LUE relationship, and the relationship was subject to change with VPD conditions higher or lower than 0.85 kPa. Seasonal evolution of crop-specific g c was modeled and communicated as a function of heat accumulation during the growing season. The research findings contribute to quantification of critical parameters that bridge water and light use efficiency, and better understanding of the resource use in C 3 and C 4 agricultural row crops.

Enhanced coupling of light use efficiency and water use efficiency in arid and semi‐arid environments

“…Higher LUE could lead to an increase of GPP , which would relieve carbon starvation and facilitate water transport. The R 2 between WUE and GPP was higher in drylands than in fields (Kukal & Irmak, 2020), and the R 2 between LUE and WUE increased when water stress was high. Drought thus seemed to enhance the correlation between LUE and WUE .…”

“…The variation of r indicated that the relationship would enhance with increasing water stress (Huang et al, 2017). The relationship between LUE and WUE of irrigated crops is controlled by VPD (Kukal & Irmak, 2020). However, VPD also significantly affects LUE of irrigated crops, particularly under moist conditions (Yuan et al, 2019).…”

“…However, most studies have focused separately on changes of LUE and WUE as well as their driving factors (Fei et al, 2019; Liu et al, 2019; Lu & Wang, 2019; Sun et al, 2016). In irrigated agriculture, the coefficient of determination ( R 2 ) between LUE and WUE achieved 50% (Kukal & Irmak, 2020), indicating that LUE has a significant effect on WUE . In a temperate deciduous broadleaf forest, changes of gross primary production (GPP) significantly affected WUE (Jin et al, 2017).…”

The Interrelationship Between Water Use Efficiency and Radiation Use Efficiency Under Progressive Soil Drying in Maize

“…High WUE was proved to be related to low RUE under probable drought (Dercas and Liakatas, 2006). In contrast, WUE and RUE are directly proportional under optimal growth conditions (Ullah et al, 2019;Kukal and Irmak, 2020). However, little is known about the interrelationships of radiation and water use processes at both leaf and canopy levels in agricultural ecosystems.…”

“…In addition, the connection between WUE and RUE response to progressive soil drying at different growth stages remains unclear. WUE and RUE are inversely related to canopy conductance (gc) (Sadras et al, 1991;Hernández et al, 2021), which may be suitable to distinguish and communicate the WUE and RUE relations (Kukal and Irmak, 2020). In addition, changes in canopy structure [e.g., leaf angle, plant height, leaf area index (LAI)] reflect both in light transmittance, and reflectance under water stress conditions (Holmes and Keiller, 2002;Onoda et al, 2014).…”