Does irrigation frequency affect stomatal response to drying soil?
Limiting agricultural water usage will be a critical issue in the 21st century due to increased competition for scant resources. One possible solution to more efficiently use available water is to apply deficit irrigation (less water than full crop evapotranspiration). The benefits of deficit irrigation under certain circumstances are well documented; however, the effects of irrigation frequency on plant physiological responses are not. Maize (Zea mays) plants were grown to a V5 development stage, then 3 treatments were applied: a control well-watered (WW) treatment, which replaced evapotranspiration losses daily, a frequent deficit irrigation (FDI) treatment aiming to keep pots at 50% of field capacity and an infrequent deficit irrigation (IDI) treatment, where the total irrigation volume given to the FDI treatment was administered every four days. The FDI treatment maintained mid-morning stomatal conductance (gs) at levels similar to that of the WW treatment, while the gs of IDI plants was only 20% of the WW. This occurred even though soil water content was comparable between FDI and IDI on the days that gs was measured. Compared to the WW treatment, leaf and xylem sap ABA concentrations within the FDI and IDI plants increased 4- and 33-fold, respectively. Compared to the WW treatment, mid-morning shoot water potential of the FDI and IDI plants decreased by 0.18 and 0.90 MPa, respectively. Compared to the WW treatment, shoot biomass (above ground) of the FDI and IDI plants decreased by 29 and 42%, respectively. Since the FDI treatment maintained gas exchange similar to WW plants despite receiving 50% less irrigation, it had the greatest water use efficiency.
Anderson, S.M., Puertolas, J. and Dodd, I.C. (2018). Does irrigation frequency affect stomatal response to drying soil?. Acta Hortic. 1197, 133-138
maize, deficit irrigation, ABA, stomatal conductance