The Influence of Short-term Partial Shading on Photosynthesis and Stomatal Conductance in Relations to Water Status of Grapevines (Vitis vinifera L.)

Vitis vinifera L. cultivars have been previously classified as isohydric, near-isohydric, anisohydric or isohydrodynamic, depending on the study. To test the hypothesis that V. vinifera cultivars’ stomatal behaviour can be separated into distinct classes, 17 cultivars grown in a replicated field trial were subjected to three irrigation treatments to manipulate vine water status across multiple years. Predawn (ΨPD) and midday (Ψl) leaf water potential and midday stomatal conductance (gs) were measured regularly throughout several seasons. The relationship of gs to Ψl was best modelled as a sigmoidal function and maximum stomatal conductance (gmax), water status at the onset of stomatal closure (Ψl95), sensitivity of closure (gsensitivity) and water status at the end of closure (Ψl25) were compared. There were no significant differences in gmax among cultivars. Cultivar-specific responses of gs to Ψl were broadly distributed along a continuum based on the relationship between Ψl95 and gsensitivity. Season-long cultivar mean Ψl values were positively related to Ψl25. In general, cultivars responded similarly to one another at high and low water status, but their stomatal behaviour differed at moderate water deficits. The results show that V. vinifera cultivars possess both iso- and anisohydric stomatal behaviours that depend on the intensity of water deficits, and call into question previous classifications assuming a single behaviour.

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Partial rootzone drying: regulation of stomatal aperture and carbon assimilation in field-grown grapevines (Vitis vinifera cv. Moscatel)

Functional Plant Biology ◽

10.1071/fp02115 ◽

2003 ◽

Vol 30 (6) ◽

pp. 653 ◽

Cited By ~ 116

Author(s):

Claudia R. de Souza ◽

João P. Maroco ◽

Tiago P. dos Santos ◽

M. Lucília Rodrigues ◽

Carlos M. Lopes ◽

...

Keyword(s):

Stomatal Conductance ◽

Vitis Vinifera ◽

Isotope Composition ◽

Leaf Gas Exchange ◽

Water Status ◽

Stomatal Closure ◽

Carbon Assimilation ◽

Quantum Yields ◽

Vitis Vinifera L ◽

Partial Rootzone Drying

The effects of 'partial rootzone drying' (PRD) irrigation compared with other irrigation systems, namely non-irrigated (NI), full irrigation (FI) and deficit irrigation (DI), on stomatal conductance and carbon assimilation were evaluated in field-grown grapevines (Vitis vinifera L. cv. Moscatel). At the end of the growing season, pre-dawn leaf water potential was highest in FI (–0.18 ± 0.01 MPa; mean ± s.e.), intermediate in PRD (–0.30�± 0.01 MPa) and DI (–0.36 ± 0.02 MPa), and lowest in NI vines (–0.64 ± 0.03 MPa). Stomatal conductance measured under controlled conditions of light and temperature was reduced in NI (ca 60%) and PRD (ca 30%) vines compared with DI and FI vines. Under ambient conditions, NI vines had lower rates of stomatal conductance (ca��26%), net CO2 assimilation (ca 28%) and light-adapted PSII quantum yields (ca 47%) than PRD, DI and FI vines. No significant differences were found among the three irrigated treatments. Both maximum electron transport rate (Jmax; ca 30%) and triose-phosphate utilization rates (TPU; ca 20%) were significantly lower in NI and PRD vines than in DI and FI vines. Carbon isotope composition (δ13C) of grape berries was highest in NI vines (–24.3), followed by PRD (–25.4) and DI (–25.8) and lowest in FI (–26.4) vines, suggesting a long-term increase in the efficiency of leaf gas exchange in NI compared with PRD, DI and FI vines. Sap-flow data and estimates of relative stomatal limitation are in accordance with the observed stomatal closure in PRD vines. In this study, we show that PRD irrigation was able to maintain a vine water status closed to FI, but with double water use efficiency, which was due to a reduction of stomatal conductance with no significant decrease in carbon assimilation.

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