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Effects of applied water amounts at various fractions of evapotranspiration (ET c ) on leaf gas exchange of Thompson Seedless grapevines
Author(s) -
WILLIAMS L.E.
Publication year - 2012
Publication title -
australian journal of grape and wine research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.65
H-Index - 77
eISSN - 1755-0238
pISSN - 1322-7130
DOI - 10.1111/j.1755-0238.2011.00176.x
Subject(s) - evapotranspiration , transpiration , stomatal conductance , water content , horticulture , water use efficiency , vine , irrigation , soil water , zoology , diurnal temperature variation , lysimeter , chemistry , agronomy , environmental science , photosynthesis , botany , biology , engineering , geology , ecology , geotechnical engineering , atmospheric sciences , soil science
Aims: To determine the effects of applied water amounts at various fractions (0.2, 0.6, 1.0 and 1.4) of grapevine evapotranspiration on leaf gas exchange of Thompson Seedless grapevines. Methods and Results: Midday stomatal conductance (g s ) decreased linearly as leaf water potential (Ψ l ) and soil water content decreased. Leaf net CO 2 assimilation rate only decreased once midday Ψ l values were less than −1.0 MPa and when ∼50% of the soil water content at field capacity had been depleted. The mean seasonal midday A/g s ratio (intrinsic water use efficiency) was greatest for the 0.2 irrigation treatment and decreased as applied water amounts increased. Diurnal A and g s for vines irrigated at the 0.6 level or greater reached a maximum prior to midday remained constant thereafter before decreasing late in the afternoon, while those for vines that received less water decreased subsequent to the first measurement of the day. Conclusions: A and g s responded differently to vine and soil water statuses under the conditions of this study. There was no midday depression in either A or g s for vines irrigated at full evapotranspiration. Significance of the Study: The values of Ψ l , A and g s reported here would serve as criteria to indicate that vines were well watered.