RT Journal Article
SR Electronic
T1 Gas Exchange and Water Relations in Field-Grown Sauvignon blanc Grapevines
JF American Journal of Enology and Viticulture
JO Am J Enol Vitic.
FD American Society for Enology and Viticulture
SP 423
OP 428
DO 10.5344/ajev.1994.45.4.423
VO 45
IS 4
A1 A. Naor
A1 B. Bravdo
A1 J. Gelobter
YR 1994
UL http://www.ajevonline.org/content/45/4/423.abstract
AB Two post-veraison irrigation levels, 1.0 and 3.5 mm/day [low (L) and control (C) treatments, respectively] were applied in an eight-year-old Sauvignon blanc vineyard. Simultaneous measurements of gas exchange parameters and leaf water potential (LWP) were made on the same leaves four weeks after veraison. Midday LWP at veraison was -1.2 MPa. A significant difference between treatments developed from veraison to mid-August. Midday LWPs in mid-August were -2 MPa and -1.4 MPa for the L and the C treatments, respectively. Photosynthesis rate (A) was found to decline with LWP with no differences between treatments. The similar ratio of stomatal conductance (gs) to A in both treatments suggests that water stress did not affect the photosynthetic apparatus. However a temporary decrease in non-stomatal conductance was detected below LWPs of -1.5 MPa. Similar gs-LWP relationships in both treatments indicates that osmotic adjustment was not responsible for the differences measured between the two irrigation treatments. A direct effect of vapor pressure gradient on gs was indicated.