Skip to main content
ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #407335
Research Project: Improving Crop Performance and Precision Irrigation Management in Semi-Arid Regions through Data-Driven Research, AI, and Integrated Models

Location: Water Management and Systems Research

Title: Diurnal trends of maize canopy cover under water stress

Author
item Dejonge, Kendall
item Zhang, Huihui
item CUMMINS, L - Colorado Division Of Water Resources
item GILKERSON, T - Us National Park Service
item ASCOUGH, K - Wyoming Department Of Transportation
item Pokoski, Tyler

Submitted to: Journal of Natural Resources and Agricultural Ecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2024
Publication Date: 5/7/2024
Citation: DeJonge, K.C., Zhang, H., Cummins, L., Gilkerson, T., Ascough, K., Pokoski, T.C. 2024. Diurnal trends of maize canopy cover under water stress. Journal of Natural Resources and Agricultural Ecosystems. 2(2):77-89. https://doi.org/10.13031/jnrae.15792.
DOI: https://doi.org/10.13031/jnrae.15792

Interpretive Summary: Water stress can cause crops to curl their leaves, which reduces the fractional canopy (fc) and the associated water use (transpiration). This study found that fc can be used to estimate water stress in maize, by measuring fc in the early morning to determine a potential transpiration, and in mid-day to determine water use reduction due to stress. In summary, this study provides a new method for estimating water stress in maize using fractional canopy cover. This method can be used to help farmers manage their irrigation systems and ensure that their crops are getting the water they need.

Technical Abstract: By differentiating green and non-green pixels of RGB images of crop canopy, the fractional canopy cover (fc, %) can be estimated, and can subsequently be used to estimate crop transpiration demand (e.g. Kcb, basal crop coefficient, following FAO-56 methodology). While unstressed crops maintain consistent fc through the day, leaves of heat or water stressed crops will curl, thereby reducing the instantaneous fc and the associated transpiration. This paper studies the effects of diurnal leaf curl on full and limited water treatments of irrigated maize, and suggests that fc images for the purpose of FAO-56 dual crop coefficient methods be representative of a non-stressed condition (i.e. fcNS), and obtained in early morning at times of low evaporative demand or following watering events where water stress has been eliminated. Reduction of fc throughout the day (i.e., fc/fcNS) was compared to water stress coefficient Ks obtained from neutron probe and TDR measurement, and showed that fc/fcNS from hours 1100-1400 had a high correlation (R2 = 0.8 ), indicating that mid-day fractional canopy cover reduction could be used as a proxy for Ks.