Chemical signals and their regulations on the plant growth and water use efficiency of cotton seedlings under partial root-zone drying and different nitrogen applications

Abstract

Partial root-zone drying during irrigation (PRD) has been shown effective in enhancing plant water use efficiency (WUE), however, the roles of chemical signals from root and shoot that are involved and the possible interactions affected by nitrogen nutrition are not clear. Pot-grown cotton ( spp.) seedlings were treated with three levels of N fertilization and PRD. The concentrations of nitrate (NO), abscisic acid (ABA) and the pH value of leaf and root xylem saps, biomass and WUE were measured. Results showed that PRD plants produced larger biomass and higher WUE than non-PRD plants, with significant changes in leaf xylem ABA, leaf and root xylem NO concentrations and pH values, under heterogeneous soil moisture conditions. Simultaneously, high-N treated plants displayed larger changes in leaf xylem ABA and higher root xylem NO concentrations, than in the medium- or low-N treated plants. However, the WUE of plants in the low-N treatment was higher than that of those in the high- and medium-N treatments. PRD and nitrogen levels respectively induced signaling responses of ABA/NO and pH in leaf or root xylem to affect WUE and biomass under different watering levels, although significant interactions of PRD and nitrogen levels were found when these signal molecules responded to soil drying. We conclude that these signaling chemicals are regulated by interaction of PRD and nitrogen status to regulate stomatal behavior, either directly or indirectly, and thus increase PRD plant WUE under less irrigation.

Nitrogen modulates cotton root morphology by affecting abscisic acid (ABA) and salicylic acid (SA) content

“…This is consistent with the result of Staswick regarding the antagonism of SA and IAA signals (Staswick et al 2002). Li et al (2017) also found that high nitrogen concentrations (375 kg N ha −1 ) were associated with larger changes in leaf xylem ABA compared to moderate or low nitrogen concentrations (262.5 kg N ha −1 and 150 N ha −1 ). This is consistent with our results in cotton root systems.…”

Canopy temperature of high‐nitrogen water‐stressed cotton

“…Increasing N supply amplified the accumulation of ABA, ABA‐GE, and phaseic acid. This agrees with a recent study (Li, Jia, & Wang, 2017), which showed consistently higher levels of xylem sap ABA in water‐stressed cotton plants grown on more soil N. These responses of ABA and stomatal conductance to high N in water‐stressed cotton contributed to warmer cotton Tc of plants supplied higher N.…”

Physiological response of maize and soybean to partial root-zone drying irrigation under N fertilization levels

“…Wang et al (2008) demonstrated that the maximum biomass accumulation of maize was obtained under well-watered conditions, but a severe water deficit caused a 50% reduction under CI; such reduction was much smaller under APRI, similar to this study. Li et al (2017) advocated that PRD improved biomass accumulation more compared to non-PRD treatments. A previous study demonstrated that total dry mass accumulation was high under higher fertilization than low fertilization treatment (Li et al, 2010a).…”

“…Spatially variable water application with PRD causes change of soil moisture within the rhizosphere, influencing N availability and plant N uptake (Han, 2013). Some studies have reported that PRD significantly improved N uptake, with increases of 15 to 100% compared to FPRI, when N application was combined (Zhang et al, 2014;Li et al, 2017). Nitrogen use efficiency under PRD was significantly greater than under CI (Ebrahimian et al, 2013;Zhang et al, 2014).…”