PERFORMANCE OF GRAPEVINES UNDER IRRIGATION SYSTEMS - Management, Performance, and Applications of Micro Irrigation Systems - page 253

optimum growth, grape yield and grape quality was possible with controlled irrigation
during certain phenological stages of vine growth. Rakhlmanina et al. [69] indicated
that the grape yield under drip irrigation were 4.50, 10.13 and 18.50 tons/ha i n 1985,
1987 and 1988, respectively; compared to 1.50, 4.38 and 4.25 tons/ha under furrow
irrigation and, respectively.
Kramer and Boyer [52] stated that the leaf photosynthetic production was decreased
if vines experience drought stress during ripening. The vine stomatal is sensitive to
water defi cits and will close to prevent excessive loss of water through transpiration.
Stomata closure during part of the day prevents carbon dioxide from entering the leaves
and inhibits photosynthesis. Bravdo et al. [14] reviewed grape vine response to crop
load and irrigation treatments. Three drip irrigation schedules were applied. Crop load
(yield/pruning weight) was affected by irrigation due to a differential effect of irriga-
tion on fruit bud differentiation and on vegetative growth. Ginestar et al. [32] indicated
that under different levels of irrigation based on transpiration data measured using sap-
fl ow sensors were applied to grape vines grown on a two-wire vertical system. Data
for the vines on the upper and lower wire were studied separately. Leaf area, yield and
water use of vines in different treatments were closely related to the intensity and dura-
tion of stress in each treatment. Irrigation increased grape yield and differences in vine
water status led to differences in the leaf area to fruit weight ratio. It was concluded that
data from the sap-fl ow sensors can be used as a basis for calculating irrigation amounts
to infl uence vine water status, canopy size, and grape yield.
Karasov [46] defi ned water use effi ciency (WUE), which is the ratio of economic
yield to total crop water use. WUE can also be defi ned as the ratio of weight of har-
vested crop to total crop water use (cm). Sinclair et al. [74] described WUE on various
scales from the leaf to the yield. In its simplest terms, it is characterized as crop yield
per unit of water used. At a more biological level, it is the carbohydrate formed through
photosynthesis from CO 2 , sunlight, and water per unit of transpiration. Brown [16] has
proposed that the upcoming benchmark for expressing yield may be the amount of wa-
ter required to produce a unit of crop yield, which is simply the long-used transpiration
ratio, or the inverse of WUE. Often the term WUE becomes confounded when used in
irrigated agriculture.
Tosso And Torres [77] evaluated effects of four irrigation levels (0.2, 0.5, 0.8 and
1.1 class A pan evaporation, Epan) and three irrigation systems (drip, sprinkler, fur-
row) on Muscat Rose var. Mosada. The lowest level of irrigation resulted in soil water
defi cits in all irrigation systems. Water application corresponding to 0.5Epan through-
out the season satisfi ed the grape water requirements. WUE was the highest with drip
irrigation, which used 50-60% less water than sprinkler and furrow irrigation and pro-
duced up to 60 kg of grapes per mm of water applied. Araujo et al. [5] studied the re-
sponse of three years old grapevines to furrow and drip irrigation; and the results were
expressed in terms of water status, crop growth and WUE. Drip irrigation was applied
daily according to best estimates of vineyard ET, while furrow irrigation was applied
when 50% of the plant available soil water content had been depleted. Drip and fur-
row irrigated vines showed similar water status and shoot growth patterns throughout
the season. Dry weight partitioning was not signifi cantly different between treatments