Irrigation Scheduling Using Predawn Leaf Water Potential Improves Water Productivity in Drip‐Irrigated Cotton

Abstract

To address the effectiveness of predawn leaf water potential in plant‐based irrigation scheduling, Gossypium hirsutum L. plants were grown under fully irrigated and dryland conditions and under three predawn water potential (ΨPD) thresholds (−0.5, −0.7, and −0.9 MPa). Measurements included ΨPD, plant height, mainstem node number, lint yield, water productivity, and continuous crop canopy temperature. We found that ΨPD produced similar yields to current practices, while decreasing overall water use from 7 to 31%, depending on rainfall levels and the treatment utilized. When considered across both years of the study (2013 and 2014), using a −0.5‐MPa ΨPD irrigation threshold consistently resulted in less irrigation applied than the checkbook method and maximum water productivity and lint yield. Using a well‐watered baseline developed in 2013 for canopy temperature versus vapor pressure deficit, we calculated a crop water stress index (CWSI) that exhibited a very strong, nonlinear relationship with season average ΨPD values between approximately −0.4 and −0.7 MPa (r2 = 0.81). A strong, nonlinear relationship was also seen between CWSI and lint yield (r2 = 0.81). Predawn water potential appears to be an effective means of determining the need for irrigation in cotton, and in the current study, yield and water productivity were maximized at a season‐long average ΨPD threshold of −0.5 MPa. Furthermore, when calibrated using ΨPD–based irrigation triggers, canopy‐temperature derived CWSI appears to be a promising tool for future automated plant‐based irrigation scheduling in the southeastern United States.

Assessing the Utility of Primed Acclimation for Improving Water Savings in Cotton using a Sensor‐Based Irrigation Scheduling System

“…Regulated deficit irrigation (RDI) was a method developed by Mitchell et al (1984), which uses water deficits timed to particular crop growth stages in an effort to conserve water while avoiding yield losses typically seen in season-long deficit irrigation schemes. Fereres and Soriano (2007) demonstrated that RDI initiated during vegetative growth stages increased water productivity (agricultural product per unit of water supplied by rainfall and irrigation; Ali and Talukder, 2008;Chastain et al, 2016; also referred to as WUE by Whitaker et al, 2008) and producer profits when using deficits ranging from 60% to as high as 100% of evapotranspiration in fruit trees and vines). Fereres and Soriano (2007) demonstrated that RDI initiated during vegetative growth stages increased water productivity (agricultural product per unit of water supplied by rainfall and irrigation; Ali and Talukder, 2008;Chastain et al, 2016; also referred to as WUE by Whitaker et al, 2008) and producer profits when using deficits ranging from 60% to as high as 100% of evapotranspiration in fruit trees and vines).…”

Integrating SEBAL with in-Field Crop Water Status Measurement for Precision Irrigation Applications—A Case Study

“…Variable rate irrigation (VRI) has been demonstrated to provide better water use efficiency (WUE) while increasing crop yields [4][5][6]. VRI systems are today integrated with a wide variety of information in order to define proper rates for each irrigation management zone (IMZ), ranging from soil moisture sensing to thermal imagery [7][8][9][10].…”

Applying plant-based irrigation scheduling to assess water use efficiency of cotton following a high-biomass rye cover crop

“…This method prevents water from being the limiting factor for cotton production systems in Georgia (Meeks 2013;Chastain et al 2014Chastain et al , 2016. However, from the physiologist's perspective, irrigation triggers that use the plant to sense its environment offer advantages over the water balance approaches discussed previously, because the cotton plant integrates soil, atmospheric, and plant factors so that the need for irrigation can be accurately determined from the water status of the plant (Jones 2007;Chastain et al 2014Chastain et al , 2016. Leaf water potential (Ψ l ) is a direct measure of the energy status of water expressed in units of pressure (Jones 2007).…”