Hydraulic and chemical signalling in the regulation of stomatal conductance and plant water use in field grapevines growing under deficit irrigation

2008 ◽  
Vol 35 (7) ◽  
pp. 565 ◽  
Author(s):  
M. Lucília Rodrigues ◽  
Tiago P. Santos ◽  
Ana P. Rodrigues ◽  
Claudia R. de Souza ◽  
Carlos M. Lopes ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Water Availability ◽  
Dominant Role ◽  
Xylem Sap ◽  
Soil Water Availability ◽  
Vitis Vinifera L ◽  
Plant Water ◽  
Chemical Signalling ◽  
Plant Water Use

Effects of irrigation strategies on stomata and plant water use were studied in field-grown grapevines (Vitis vinifera L.). We assessed the importance of root-derived chemical signals vs. hydraulic signalling in stomatal regulation. The experiment included two treatments with the same water added to the soil (50% ETc) applied either to the whole root system (DI) or to half of the roots, alternating irrigation side every 15 days (PRD). Well-watered plants (FI) (100% ETc) and non-irrigated grapevines (NI) were also studied. Partial stomata closure occurred in both PRD and DI plants. [ABA] of xylem sap remained constant during the day and was maintained throughout the season, with higher values in NI plants. Xylem sap pH was not affected by soil water availability. A positive correlation between ψpd and maximum g s was found, indicating that grapevine stomata strongly respond to plant water status. In contrast, ABA did not explain stomatal control at veraison. At mid-ripening g s was significantly correlated with ABA, apparently interacting with the rise in xylem sap pH. Therefore, our data suggest that hydraulic feedback and feed-forward root-to-shoot chemical signalling mechanisms might be involved in the control of stomata in response to decreased soil water availability, hydraulic signals playing the dominant role.

Functional Differences in Soil Water Pools: a New Perspective on Plant Water Use in Water-Limited Ecosystems

2008 ◽  
pp. 397-422 ◽  
Author(s):  
Ronald J. Ryel ◽  
Carolyn Y. Ivans ◽  
Michael S. Peek ◽  
A. Joshua Leffler
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Plant Water ◽  
Functional Differences ◽  
Plant Water Use ◽  
New Perspective

scholarly journals Soil moisture heterogeneity regulates water use in Populus nigra L. by altering root and xylem sap phytohormone concentrations

2020 ◽  
Vol 40 (6) ◽  
pp. 762-773 ◽  
Author(s):  
Jaime Puértolas ◽  
Marta Pardos ◽  
Carlos de Ollas ◽  
Alfonso Albacete ◽  
Ian C Dodd
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Deficit Irrigation ◽  
Xylem Sap ◽  
Irrigation Scheduling ◽  
Populus Nigra ◽  
Soil Drying ◽  
Plant Water ◽  
Plant Water Use ◽  
Soil Moisture Heterogeneity

Abstract Soil moisture heterogeneity in the root zone is common both during the establishment of tree seedlings and in experiments aiming to impose semi-constant soil moisture deficits, but its effects on regulating plant water use compared with homogenous soil drying are not well known in trees. Pronounced vertical soil moisture heterogeneity was imposed on black poplar (Populus nigra L.) grown in soil columns by altering irrigation frequency, to test whether plant water use, hydraulic responses, root phytohormone concentrations and root xylem sap chemical composition differed between wet (well-watered, WW), and homogeneously (infrequent deficit irrigation, IDI) and heterogeneously dry soil (frequent deficit irrigation, FDI). At the same bulk soil water content, FDI plants had greater water use than IDI plants, probably because root abscisic acid (ABA) concentration was low in the upper wetter layer of FDI plants, which maintained root xylem sap ABA concentration at basal levels in contrast with IDI. Soil drying did not increase root xylem concentration of any other hormone. Nevertheless, plant-to-plant variation in xylem jasmonic acid (JA) concentration was negatively related to leaf stomatal conductance within WW and FDI plants. However, feeding detached leaves with high (1200 nM) JA concentrations via the transpiration stream decreased transpiration only marginally. Xylem pH and sulphate concentration decreased in FDI plants compared with well-watered plants. Frequent deficit irrigation increased root accumulation of the cytokinin trans-zeatin (tZ), especially in the dry lower layer, and of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), in the wet upper soil layer. Root hormone accumulation might explain the maintenance of high root hydraulic conductance and water use in FDI plants (similar to well-watered plants) compared with IDI plants. In irrigated tree crops, growers could vary irrigation scheduling to control water use by altering the hormone balance.

scholarly journals Carbon–water flux coupling under progressive drought

2019 ◽  
Vol 16 (13) ◽  
pp. 2557-2572 ◽  
Author(s):  
Sven Boese ◽  
Martin Jung ◽  
Nuno Carvalhais ◽  
Adriaan J. Teuling ◽  
Markus Reichstein
Keyword(s):  
Water Use Efficiency ◽  
Soil Water ◽  
Water Use ◽  
Water Availability ◽  
Carbon Assimilation ◽  
Soil Water Availability ◽  
Natural Experiments ◽  
Water Limitation ◽  
Dry Down ◽  
Use Efficiency

Abstract. Water-use efficiency (WUE), defined as the ratio of carbon assimilation over evapotranspiration (ET), is a key metric to assess ecosystem functioning in response to environmental conditions. It remains unclear which factors control this ratio during periods of extended water limitation. Here, we used dry-down events occurring at eddy-covariance flux tower sites in the FLUXNET database as natural experiments to assess if and how decreasing soil-water availability modifies WUE at ecosystem scale. WUE models were evaluated by their performance to predict ET from both the gross primary productivity (GPP), which characterizes carbon assimilation at ecosystem scale, and environmental variables. We first compared two water-use efficiency models: the first was based on the concept of a constant underlying water-use efficiency, and the second augmented the first with a previously detected direct influence of radiation on transpiration. Both models predicting ET strictly from atmospheric covariates failed to reproduce observed ET dynamics for these periods, as they did not explicitly account for the effect of soil-water limitation. We demonstrate that an ET-attenuating soil-water-availability factor in junction with the additional radiation term was necessary to accurately predict ET flux magnitudes and dry-down lengths of these water-limited periods. In an analysis of the attenuation of ET for the 31 included FLUXNET sites, up to 50 % of the observed decline in ET was due to the soil-water-availability effect we identified in this study. We conclude by noting that the rates of ET decline differ significantly between sites with different vegetation and climate types and discuss the dependency of this rate on the variability of seasonal dryness.

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