Effect of Partial Root-Zone Drying Irrigation (PRD) on the Gas Exchange and Antioxidant Enzymatic Activities in Alfalfa

Partial root‐zone drying irrigation improves intrinsic water‐use efficiency and maintains high photosynthesis by uncoupling stomatal and mesophyll conductance in cotton leaves

“…Previous studies on the effects of PRD on stomatal functions of cotton (Du et al, 2006), alfalfa (Medicago sativa) (Zhang, Liu, et al, 2019) and tobacco (Nicotiana tabacum) (Liu et al, 2021) reported significant decreases in g s while unaffected A N . According to F I G U R E 1 Application of partial root-zone irrigation in a cotton field (a).…”

“…Previous studies on the effects of PRD on stomatal functions of cotton (Du et al, 2006), alfalfa ( Medicago sativa ) (Zhang, Liu, et al, 2019) and tobacco ( Nicotiana tabacum ) (Liu et al, 2021) reported significant decreases in g s while unaffected A N . According to the authors, this discrepancy was attributed to the dried side of the root system triggering root‐to‐shoot signals, such as abscisic acid (ABA), that induced a partial stomatal closure, while the well‐watered side of the root system maintained the water status of the leaves by being able to absorb enough water (Ghafari et al, 2020).…”

“…Accordingly, PRD was observed to significantly decrease g s (Du et al, 2006;Liu et al, 2021;Zhang, Liu, et al, 2019), indicating that the limiting effect of g s to A N could be altered, with potentially further consequences on the relative contribution of stomatal conductance, mesophyll conductance and biochemical limitations (annotated as l s , l m and l b , respectively) on A N . Further research, however, is evidently required to confirm this assumption.…”

“…Regarding PRD, little attention has been given to its effects on leaf morphoanatomical traits that affect g m . In more detail, with the exception of LMA, where variable results have been recorded among different species (Hooshmand et al, 2019; Kusakabe et al, 2009; Sun et al, 2014; Zhang, Liu, et al, 2019), and T leaf , which was increased under PRD conditions in tobacco (Liu et al, 2021), limited to zero information exist on the rest of the g m ‐related traits and their responses to PRD.…”

“…Based on that, Grassi and Magnani (2005) established an evaluation method to calculate the individual limiting effects of g s , g m and photosynthetic biochemistry on A N , and this approach has been applied in many studies (Han et al, 2018; Lei et al, 2022; Wang et al, 2018). Accordingly, PRD was observed to significantly decrease g s (Du et al, 2006; Liu et al, 2021; Zhang, Liu, et al, 2019), indicating that the limiting effect of g s to A N could be altered, with potentially further consequences on the relative contribution of stomatal conductance, mesophyll conductance and biochemical limitations (annotated as l s , l m and l b , respectively) on A N . Further research, however, is evidently required to confirm this assumption.…”