Substantial Nighttime Evapotranspiration in Lettuce Grown Under Controlled-Environment Conditions

Authors

• Claudia Garrido-Ruiz, Utah State UniversityFollow
• Juan D. González-Teruel, Utah State University
• Scott B. Jones, Utah State University
• Bruce Bugbee, Utah State University

Document Type

Article

Journal/Book Title/Conference

Smart Agricultural Technology

Author ORCID Identifier

Claudia Garrido-Ruiz https://orcid.org/0000-0003-1539-4842

Juan D. González-Teruel https://orcid.org/0000-0001-6746-2961

Scott B. Jones https://orcid.org/0000-0002-3804-8785

Volume

14

Publisher

Elsevier BV

Publication Date

6-16-2026

Journal Article Version

Version of Record

First Page

1

Last Page

10

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.

Abstract

Nighttime evapotranspiration (ET_n) has been widely reported across plant species, yet its magnitude and physiological significance in controlled-environment crop production remain poorly understood. This study quantified ET_n in lettuce (Lactuca sativa L. cv. Outredgeous) grown under controlled-environment conditions and evaluated nighttime-to-daytime ET dynamics under contrasting surface cover conditions. Plants were grown in peat-based root modules operated as zero-drainage systems, allowing ET to be quantified from continuous mass loss of individual nutrient reservoirs. Two surface treatments were compared: uncovered growth media and growth media covered with flexible silicone-rubber sheets incorporated as part of the evaluated growth-system configuration, which also suppressed evaporation (E). ET was partitioned into modeled E and modeled transpiration (T) components using the fraction of canopy cover derived from digital image analysis. During early development, modeled E was reduced by 87% in covered modules, enabling evaluation of ET_n under minimized E conditions. After canopy closure, when T accounted for nearly all measured ET, the hourly nighttime-to-daytime ET ratio (ET_n/ET_d) averaged 0.46 for the uncovered treatment and 0.42 for the covered treatment (p < 0.001), indicating that substantial nighttime water loss persisted primarily through T in both treatments. However, these ET_n/ET_d ratios were only approximately half of the estimated apparent nighttime-to-daytime canopy stomatal conductance ratios (g_sn/g_sd), which averaged 0.82 and 0.75 in the uncovered and covered treatments, respectively. This difference indicates that nighttime ET was limited mainly by reduced evaporative demand, even though apparent canopy gs remained relatively close to daytime levels. Overall, silicone-rubber covers reduced cumulative water use by 32% without affecting biomass production, increasing water-use efficiency (WUE) from 2.5 to 3.8 g dry matter L^-1 nutrient solution. These results demonstrate that substantial ET_n persisted after canopy closure and was consistent with sustained nocturnal stomatal conductance under controlled-environment conditions, indicating that ET_n can represent a major non-productive component of crop water use when E is minimized. Accounting for ET_n may therefore improve ET estimates, water-use assessments, and environmental control strategies in controlled-environment agricultural systems.

Recommended Citation

Garrido-Ruiz, C.; González-Teruel, J.D.; Jones, S.B.; Bugbee, B. Substantial Nighttime Evapotranspiration in Lettuce Grown under Controlled-Environment Conditions. Smart Agric. Technol. 2026, 14, 102326, doi:10.1016/j.atech.2026.102326.