Journal
ENVIRONMENTAL AND EXPERIMENTAL BOTANY
Volume 139, Issue -, Pages 99-104Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.envexpbot.2017.04.008
Keywords
Abscisic acid; Climate change; Leaf turgor; Root-to-shoot signaling; Water use efficiency
Categories
Funding
- Villum Foundation Block Stipend [341/300-123012]
- Sino-Danish Center for Research and Education (SDC)
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The objective of this study was to investigate the relative significance of hydraulic and chemical signals in controlling stomatal conductance (g(s)) of drought-stressed tomato plants grown under ambient (a[CO2], 400 ppm) and elevated atmospheric CO2 concentration (e[CO2], 800 ppm). The fraction of transpirable soil water (FTSW) was lower and decreased much faster in plants grown at e[CO2] than those grown at a[CO2]. During soil drying, midday leaf water potential (Psi(1)), osmotic potential (Psi pi), and turgor pressure (Psi) were kept constant until FTSW reached ca. 0.2; while the plants grown under e[CO2] had significantly lower 11-17G but significantly higher 'FP than those grown under a[CO2]. The A(n) was significantly greater in plants grown under e [CO2] than those grown under a[CO2] during soil drying. The g(s) was significant higher for plants grown under a [CO2] at onset of drought but decreased linearly with decreasing FTSW, whereas it was kept almost unchanged from onset of drought until FTSW reached ca. 0.2 in plants grown under e[CO2]. The intrinsic water use efficiency (WUEi) increased linearly with decreasing FTSW to ca. 0.2 in plants grown under a[CO2], while a decline of WUEi was observed for plants grown under e[CO2]. The xylem sap ABA concentration ([ABA](xylem)) increased exponentially with decreasing FTSW, and the increase was more pronounced in plants grown under e [CO2]. When FTSW > 0.3, g(s) decreased linearly with increasing [ABA](xylem) for plants grown under a[CO2]; while for plants grown under e[CO2], g, decreased linearly with decreasing gyp, indicating that at moderate drought stress the g, of tomato leaves was mainly regulated by the xylem -borne ABA signaling when grown at a [CO2]; whereas under e[CO2] the g(s) was insensitive to [ABA](xylem) and controlled predominantly by Psi p. The results provide some novel insights into the mechanisms of plant response to drought stress in future CO2 enriched environment.
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