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Effects of irrigation deprivation during the harvest period on leaf persistence and function in mature almond trees
Year:
2001
Source of publication :
tree physiology (source)
Authors :
Klein, Isaac
;
.
Volume :
21
Co-Authors:
Klein, I., Department of Pomology, University of California, Davis, CA 95616, United States
Esparza, G., Department of Pomology, University of California, Davis, CA 95616, United States
Weinbaum, S.A., Department of Pomology, University of California, Davis, CA 95616, United States
DeJong, T.M., Department of Pomology, University of California, Davis, CA 95616, United States
Facilitators :
From page:
1063
To page:
1072
(
Total pages:
10
)
Abstract:
In nut tree orchards in California, irrigation is typically withheld during the harvest period to reduce the likelihood of bark damage during mechanical shaking of the trees. The ensuing water stress, however, may result in premature defoliation and subsequent yield declines. Our objective was to establish and quantify the water stress resulting from irrigation deprivation and determine its impact on leaf function and persistence in mature almond trees (Prunus dulcis (Mill.) D.A. Webb cv. Nonpareil) during a 3-year field experiment. The severity of the water stress was characterized by measurements of predawn leaf (Ψpd) and midday stem (Ψms) water potentials, stomatal conductance (gs), net CO2 assimilation rate (A) and leaf abscission. During 1995, Ψms of fully irrigated (FI) trees was maintained above -1.0 MPa. In trees in the moderate-(MS) and severe-stress (SS) treatments, Ψms was reduced to -1.4 to -2.0 MPa and -2.0 to -2.6 MPa, respectively. After 18 days of irrigation deprivation, A was reduced by 32 and 58% at midday and early afternoon, respectively, compared with morning values. A significant decrease in morning values of A only occurred after 30 days of irrigation deprivation. Water-use efficiency and A declined as evaporative demand increased from morning to afternoon. Assimilation also declined seasonally as leaves aged. Midday stem water potential was highly correlated with A, but less so with gs. The coefficient of determination between Ψms and gs improved considerably when vapor pressure deficit and wind were multiply regressed with Ψms. Although A recovered rapidly when MS trees were irrigated, recovery in SS trees was slower and incomplete. Integrating the MS and SS effects for an extended period during 1995 resulted in 14 and 30% declines in A, and 6 and 20% declines in gs, respectively. The apparent Ψms threshold for leaf abscission was -1.8 MPa. Daily canopy light interception declined with decreasing Ψms as a result of premature defoliation (and perhaps altered leaf angles) from 67.9% in FI trees to 61.4 and 60.7% in MS and SS trees, respectively.
Note:
Related Files :
abscission
Agriculture
California
harvesting
Prunus
water
water stress
water use efficiency
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Related Content
More details
DOI :
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
21274
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:42
Scientific Publication
Effects of irrigation deprivation during the harvest period on leaf persistence and function in mature almond trees
21
Klein, I., Department of Pomology, University of California, Davis, CA 95616, United States
Esparza, G., Department of Pomology, University of California, Davis, CA 95616, United States
Weinbaum, S.A., Department of Pomology, University of California, Davis, CA 95616, United States
DeJong, T.M., Department of Pomology, University of California, Davis, CA 95616, United States
Effects of irrigation deprivation during the harvest period on leaf persistence and function in mature almond trees
In nut tree orchards in California, irrigation is typically withheld during the harvest period to reduce the likelihood of bark damage during mechanical shaking of the trees. The ensuing water stress, however, may result in premature defoliation and subsequent yield declines. Our objective was to establish and quantify the water stress resulting from irrigation deprivation and determine its impact on leaf function and persistence in mature almond trees (Prunus dulcis (Mill.) D.A. Webb cv. Nonpareil) during a 3-year field experiment. The severity of the water stress was characterized by measurements of predawn leaf (Ψpd) and midday stem (Ψms) water potentials, stomatal conductance (gs), net CO2 assimilation rate (A) and leaf abscission. During 1995, Ψms of fully irrigated (FI) trees was maintained above -1.0 MPa. In trees in the moderate-(MS) and severe-stress (SS) treatments, Ψms was reduced to -1.4 to -2.0 MPa and -2.0 to -2.6 MPa, respectively. After 18 days of irrigation deprivation, A was reduced by 32 and 58% at midday and early afternoon, respectively, compared with morning values. A significant decrease in morning values of A only occurred after 30 days of irrigation deprivation. Water-use efficiency and A declined as evaporative demand increased from morning to afternoon. Assimilation also declined seasonally as leaves aged. Midday stem water potential was highly correlated with A, but less so with gs. The coefficient of determination between Ψms and gs improved considerably when vapor pressure deficit and wind were multiply regressed with Ψms. Although A recovered rapidly when MS trees were irrigated, recovery in SS trees was slower and incomplete. Integrating the MS and SS effects for an extended period during 1995 resulted in 14 and 30% declines in A, and 6 and 20% declines in gs, respectively. The apparent Ψms threshold for leaf abscission was -1.8 MPa. Daily canopy light interception declined with decreasing Ψms as a result of premature defoliation (and perhaps altered leaf angles) from 67.9% in FI trees to 61.4 and 60.7% in MS and SS trees, respectively.
Scientific Publication
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