CO2 Elevation and Nitrogen Supply Alter the Growth and Physiological Responses of Tomato and Barley Plants to Drought Stress

Abstract

Global climate change will modify plants in terms of growth and physiology. To better understand the consequences of this effect, the responses of the leaf water relations and nitrogen (N) use efficiency of barley and tomato plants to elevated CO2 (e[CO2], 800 ppm) combined with progressive drought stress at two levels of N supply (N1, 0.5 g N pot−1 and N2, 1.0 g N pot−1) were studied. The plants were grown in two separate phytotrons at ambient CO2 (a[CO2], 400 ppm) and e[CO2], respectively. The leaf physiological parameters as well as carbon (C) and N concentrations were determined; plant growth, water and N use efficiencies were evaluated. The results showed that e[CO2] increased photosynthesis and water use efficiency (WUE) while decreased specific leaf area (SLA) in both species, whereas N supply level differentially influenced WUE in barley and tomato plants. The abscisic acid (ABA)-induced stomatal closure during progressive soil drying varied between the two species where the stomatal conductance (gs) of barley plants was more sensitive to leaf ABA than tomato plants, though CO2 environment did not affect the response in both species. Compared to a[CO2], e[CO2] reduced plant transpiration rate (Tplant) in barley but not in tomato. e[CO2] increased the leaf C:N ratio ([C:N]leaf) in plants by enhancing leaf C concentration ([C]leaf) in barley and by dilution of leaf N concentration ([N]leaf) in tomato, respectively, but N2 substantially decreased [C:N]leaf, and thus, N treatment was the dominant factor controlling [C:N]leaf. Collectively, appropriate N supply may modulate the acclimation of plants to e[CO2] and soil water deficits. This study provides some novel insights into N management of different plant species for adapting to future drier and CO2-enriched environment.

Responses of Two-Row and Six-Row Barley Genotypes to Elevated Carbon Dioxide Concentration and Water Stress

“…In elevated CO 2 concentrations, positive correlations were observed between ShDW with GW, LA, and DPPH under normal and water stress and negative correlations with APX. This suggests that increased shoot dry weight is associated with higher levels of leaf pigments, larger leaf size, enhanced antioxidant activity, and enzymatic defense mechanisms [7,40].…”

“…Ainsworth and Rogers [37] reported increased biomass and grain yield in barley under elevated CO 2 . Additionally, elevated CO 2 has enhanced photosynthetic performance and increased carotenoid content in various plant species [7]. The increase in Fv/Fm suggests improved photosynthetic capacity and light energy utilization under elevated CO 2 conditions [38].…”

“…Despite occupying a small volume of the atmosphere (0.04%), even small changes in CO 2 levels have direct and indirect effects on plant morphology, physiology, and biochemistry [6]. Plants respond to elevated CO 2 concentrations by increasing photosynthesis rate, dry matter accumulation, and water and nutrient use efficiency [7]. In nature, plants face numerous abiotic stress factors simultaneously, which will be increasingly frequent due to climate change and affect their growth, yield, and survival.…”

Mitigating drought stress in wheat plants (Triticum Aestivum L.) through grain priming in aqueous extract of spirulina platensis

“…It is a key factor influencing CO 2 uptake by plants [ 101 ]. It is intimately linked with photosynthetic and water use efficiency, especially under drought-stress conditions [ 102 ]. In this study, the sensitive wheat cultivar Shandawel 1 showed a substantial decrease in gs under DS.…”