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קהילה:
אסיף מאגר המחקר החקלאי
פותח על ידי קלירמאש פתרונות בע"מ -
Response of citrus trees to modified radiation regime in semi-arid conditions
Year:
1997
Source of publication :
Journal of Experimental Botany
Authors :
כהן, שבתאי
;
.
לה גיו, לואיק
;
.
מורשת, שמואל
;
.
סימון, ז'אן-כריסטוף
;
.
Volume :
48
Co-Authors:
Cohen, S., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Moreshet, S., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Le Guillou, L., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel, Inst. Sup. Technique d'Outre Mer, 32 Boulevard du Port, F-95094 Cergy-Pontoise Cedex, France
Simon, J.-C., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Cohen, M., Inst. Recerca i Tecn. Agroaliment., E-08348 Cabrils, Barcelona, Spain
Facilitators :
From page:
35
To page:
44
(
Total pages:
10
)
Abstract:
Citrus trees are characterized by a large canopy and low hydraulic conductivity. In Israel's semi-arid summer climate this could cause transpiration to exceed water uptake and cause temporary excessive water deficits, it was hypothesized that reduction of radiative load would reduce transpiration and thus reduce deficits. Net radiation of lemon trees in the hottest season was reduced by shading hedgerows with reflective nets for approximately one month in both 1994 and 1995. Stem sap flow and climate variables were measured continuously. Daily courses of leaf conductance and leaf water potentials were measured on selected days. Midday net radiation below the dense and sparse shade net treatments was 47% and 73% of that above the control trees. Midday 'sunlit' leaf temperatures below the nets were reduced by 2.7 and 1.6 C, respectively. The reduction in net radiation caused large changes in leaf conductance. Average midday sunlit leaf conductance measured in 1995 under the dense and sparse treatments and control were 4.1, 2.9 and 1.8 mm s-1, respectively (significantly different at P < 0.01). Similar differences in sunlit leaf conductance were found in 1994. Shade leaf conductance was not affected by the treatments. Daily total and midday sap flow under the dense net were reduced by 6-7% and 10-11%, respectively. Sap flow under the sparse net did not change significantly in 1994, but in 1995 daily and midday sap flows were reduced by 6% and 7%, respectively. Midday leaf water potentials increased by 0.2 and 0.1 MPa under dense shade in 1994 and 1995, respectively. Under sparse shade midday leaf water potentials increased by 0.1 MPa in 1994, but did not change significantly in 1995. A modified Penman-Monteith model evaluated transpiration if leaf conductance were constant in the different radiation environments. At leaf conductance levels found in the unshaded trees, dense shade was estimated to cause a 25% reduction in transpiration, while leaf conductance values found in trees under the dense shade would lead to an increase in transpiration of more than 35% in unshaded trees. The ability of the tree to maintain almost constant transpiration in different radiation environments and thus avoid water deficit by adjusting the conductance of sunlit leaves is discussed in terms of environmental influences and significance to the plant's water balance.
Note:
Related Files :
Citrus
climate modification
stomatal closure
Tree transpiration
עוד תגיות
תוכן קשור
More details
DOI :
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
28460
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:39
Scientific Publication
Response of citrus trees to modified radiation regime in semi-arid conditions
48
Cohen, S., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Moreshet, S., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Le Guillou, L., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel, Inst. Sup. Technique d'Outre Mer, 32 Boulevard du Port, F-95094 Cergy-Pontoise Cedex, France
Simon, J.-C., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, POB 6, Bet Dagan, Israel
Cohen, M., Inst. Recerca i Tecn. Agroaliment., E-08348 Cabrils, Barcelona, Spain
Response of citrus trees to modified radiation regime in semi-arid conditions
Citrus trees are characterized by a large canopy and low hydraulic conductivity. In Israel's semi-arid summer climate this could cause transpiration to exceed water uptake and cause temporary excessive water deficits, it was hypothesized that reduction of radiative load would reduce transpiration and thus reduce deficits. Net radiation of lemon trees in the hottest season was reduced by shading hedgerows with reflective nets for approximately one month in both 1994 and 1995. Stem sap flow and climate variables were measured continuously. Daily courses of leaf conductance and leaf water potentials were measured on selected days. Midday net radiation below the dense and sparse shade net treatments was 47% and 73% of that above the control trees. Midday 'sunlit' leaf temperatures below the nets were reduced by 2.7 and 1.6 C, respectively. The reduction in net radiation caused large changes in leaf conductance. Average midday sunlit leaf conductance measured in 1995 under the dense and sparse treatments and control were 4.1, 2.9 and 1.8 mm s-1, respectively (significantly different at P < 0.01). Similar differences in sunlit leaf conductance were found in 1994. Shade leaf conductance was not affected by the treatments. Daily total and midday sap flow under the dense net were reduced by 6-7% and 10-11%, respectively. Sap flow under the sparse net did not change significantly in 1994, but in 1995 daily and midday sap flows were reduced by 6% and 7%, respectively. Midday leaf water potentials increased by 0.2 and 0.1 MPa under dense shade in 1994 and 1995, respectively. Under sparse shade midday leaf water potentials increased by 0.1 MPa in 1994, but did not change significantly in 1995. A modified Penman-Monteith model evaluated transpiration if leaf conductance were constant in the different radiation environments. At leaf conductance levels found in the unshaded trees, dense shade was estimated to cause a 25% reduction in transpiration, while leaf conductance values found in trees under the dense shade would lead to an increase in transpiration of more than 35% in unshaded trees. The ability of the tree to maintain almost constant transpiration in different radiation environments and thus avoid water deficit by adjusting the conductance of sunlit leaves is discussed in terms of environmental influences and significance to the plant's water balance.
Scientific Publication
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