The Effect of Vine Spacing on Some Physiological Aspects of Vitis
vinifera L. (cv. Pinot noir)*
E. Archer 1 and H.C. Strauss 2
I) Department of Viticulture, University of Stellenbosch. 7600 Stellenbosch. Republic of South Africa
2) Viticultural and Oenological Research Institute (YORI), Private Bag X5026, 7600 Stellenbosch, Republic of South Africa
Submitted for publication: August 1990
Accepted for publication: October 1990
Key words: Canopy characteristics, leaf-water potential, stomata! conductance. transpiration, photosynthesis
The effect of vine spacing on leaf temperature, radiant energy, some canopy characteristics, leaf-water potential, stomata!
conductance, the rate of transpiration and the rate of photosynthesis was measured and discussed. With more closely spaced
vines, canopies were less dense than with more widely spaced vines mainly because of less vigorous shoot growth. The
consequent better sunlight penetration favoured the physiology of more closely spaced vines early in the season. During the
latter part of the season the situation was reversed and the physiology of more widely spaced vines was favoured mainly
because of better water supply.
As with many other cultured crops, photosynthesis is probably
the most important physiological process in vines. The nett
photosynthetic product of a vine is the result of the contribution
of a community of individual leaves, each affected by a series
of environmental, biological and physiological factors. Environmental factors such as light, temperature and humidity
have an important effect on the photosynthesis of grapevines
and have been the subject of many studies (Kriedemann &
Smart, 1971; Kliewer, 1982; Champagnol, 1984; Smart, 1985;
Smart, Robinson, Due & Brien, l 985a, l 985b; Smart, l 987a,
1987b; Smart, Smith & Winchester, 1988). These environmental factors are frequently termed "microclimate" by various
researchers. For maximum photosynthesis, optimum
microclimate is a prerequisite.
l 985a & l 985b ). The arrangement of the leaves in vine
canopies is affected by cultural practices such as training and
trellising (Zeeman, 1981; Smart, et al., l 985a), leaf removal
(Peterson & Smart, 1975; Boniface & Dumartin, 1977;
Carbonneau et al., 1977; Williams, Biscay & Smith, 1987;
Bledsoe, Kliewer & Marois, 1988; Hunter & Visser, l 988a &
l 988b ), shoot thinning (Guyot, 1867; Archer & Beukes, 1983;
Archer, 1987; Reynolds, Pool & Mattick, 1986), and winter
pruning severity (Perold, 1927; Archer & Fouche, 1987).
These practices, therefore, have a direct effect on the efficient
utilization of sunlight energy for photosynthesis not only by
single leaves but also by canopies as a whole.
The arrangement ofleaves and shoots in a canopy, frequently
referred to as canopy density, is obviously affected by vine
vigour. Thus, factors affecting vine vigour will also affect
canopy density. Although cultural practices such as irrigation
and N-fertilization have an important effect on induced vine
vigour, genetic factors and climatic effects can not be overlooked. High canopy densities are obtained when the available
area per vine (dictated by vine spacing and the size of the
trellising system) is too small to accommodate the shoot
growth of the vine. On the other hand, low canopy densities are
obtained when the available area is too big for the existing
vegetative capacity of a vine. Ideal canopy densities are
procured when the available space (horizontal as well as
vertical) can accommodate the vegetative growth without
necessitating intensive canopy management techniques such
as shoot thinning, topping and the removal of laterals.
Although various reports dealing with the effect of different
cultural practices on microclimate were found, very little
information could be obtained on the effect of vine spacing on
the microclimate in grapevine canopies. Hedberg & Raison
( 1982) reported that diffused and reflected light was lower at
the cordon level of more closely spaced vines than in the case
of wider spacings. With orange trees, Boswell, Nauer & Atkin
(1982) reported no differences in radiation measured within
the canopies between narrowly and widely spaced trees.Ofthe
total radiation reaching the vine, mainly the part between 400
to 700 nm is used for photosynthesis; this is called photosynthetic active radiation (PAR). The quality of PAR affects
photosynthetic activity (Champagnol, 1984 ), and Smart, et al.
(1988) reported that vine physiology is affected not only by
the photosynthetic photon-fluence rate (PPFR) but also by the
ratio of red to far red (R:FR).
Canopy density per se plays an important role in leaf
temperature through sunlight penetration and air movement.
Leaf temperature has an important effect on the rate of
photosynthesis. Excessively vegetative canopies create more
shade and lower leaf temperatures than sparse canopies (Smart,
1974), whereby the photosynthetic rate of especially interior
leaves can be decreased, depending on ambient temperatures.
Photosynthesis is greatly affected by light on the leaves,
which in tum depends on the structure of the canopy, i.e. the
spatial orientation and arrangement of the leaves within the
canopy (Shaulis, Amberg & Crowe, 1966; Sparks & Larsen,
1966; Kriedemann & Smart, 1971; Smart, 1985; Smart, et al.,
*Part of a Ph.D. (Agric.) dissertation to be submitted by the senior author to the Unil'ersity of Stellenbosch. Promoter: Prof: P. G. Goussard.
Acknowledgements: The valuable assistance of J.M. Southey and G.W. Fouche is gratefully acknowledged.
S. Afr. J. Enol. Vitic., Vol.11, No. 2, 1990
76
Vine Spacing and Physiology
Leaves in sparse canopies receive more radiant energy
(Williams et al., 1987; Hunter & Visser, 1988c), whereby the
photosynthetic activity of individual leaves is increased (Smart,
1985; Hunter & Visser, 1988b). The positive effect of sparser
canopies on canopy microclimate as well as on grape quality
is well documented (Smart, 1987a; Williams et al., 1987;
Bledsoe et al., 1988; Reynolds, 1989).
Sparser canopies produce ventilated leaves and clusters
(Hunter & Visser, 1988c) and improved sunlight penetration
(Archer 1987; Archer & Strauss, 1989; Reynolds & Wardle,
1989). Sparks & Larsen ( 1966) found that increased canopy
density (increasing within-canopy shade) decreased the sugar
concentration and also negatively affected bud fertility
(Morgan, Stanley & Warrington, 1985). Smart ( 1987a) pointed
out that sunlight can affect fruit composition through photosynthetic, thermal or phytochrome effects and that light quality
could play an important role in the quality of the grape. On the
other hand, grape quality can be negatively affected through
high temperatures obtained in well-exposed bunches in sparse
canopies with little or no air movement (Smart, 1987a; Smart
& Sinclair, 1976).
Smart, Smith & Winchester ( 1988) and Archer & Strauss
( 1989) reported negative morphological and grapecompositional effects in shaded Cabernet Sauvignon fruit. An
increase in within-canopy shade was responsible for a decline
in berry set, sugar, skin anthocyanins and phenols, while malic
acid, K-concentration and pH increased. Similarly. Bledsoe,
Winkler & Marois (1988) reported a significantly negative
correlation between the PPFR and the pH, malate and Kconcentration.
Canopies with relatively low densities, bearing well-exposed fruit, have big advantages as far as grape and potential
wine quality is concerned if water stress during ripening and
direct cluster exposure do not exceed certain limits. It is not
clear. however, to what extent the positive effects of sparse
canopies would be offset by the negative effects of high plant
water stress as obtained in vineyards with little or no irrigation. This study was undertaken to establish the effect of vine
spacing on canopy characteristics and on some microclimatic
and physiological aspects of vines in order to ex plain possible
differences in grape and wine quality. The quantitative and
qualitative effects of vine spacing will be dealt with in a later
publication.
MATERIALS AND METHODS
Vineyard: A Vitis vinifera L. cv. Pinot noir (clone BKV)
grafted onto 99 Richter (clone 1/30/I) (Vitis Berlandieri var.
Las Sorres x Vi tis rupestris var. du Lot) vineyard was planted
during 1980 with spacings as indicated in Table I.
Each spacing treatment was randomly replicated in blocks,
five times, and side-effects were eliminated by border rows
giving approximately 49 vines per replicate for measurement.
The vines were trained on a 4-strand Hedge system (cordon
height: 600 mm; foliage height: 1 800 mm with foliage wires
evenly spaced 300 mm apart). During the first two years no
crop was allowed in order to obtain a complete development
of the vines on the trellising system. Thereafterthe vines were
spur-pruned to 6,5 buds per m 2 soil surface. All vines were
shoot-thinned at approximately 150-mm shoot length and
77
TABLE 1
Treatments used in a vine spacing trial with Pinot noir/99
Richter.
Inter-row spacing
(m)
In-row spacing
(m)
Number of vines per
hectare
1,0
1,0
2,0
2,0
3,0
3,0
0,5
1,0
1,0
2,0
1,5
3,0
20 000
IO 000
5 000
2 500
2 222
I Ill
shoots were tipped once at a height of approximately 200 mm
above the top foliage wire. The vines in different spacing
treatments were differentially fertilized on the basis of crop
mass and cane mass in order to replenish soil nutrients to a
comparable amount for each espacement. No irrigation was
applied. The soil used for the trial is described by Archer &
Strauss ( l 989b ).
Measurements: During the season when these measurements were made, the monthly rainfall was as follows: Sept.
38,9 mm, Oct. 22,7 mm, Nov. 10,6 mm, Dec. 4,3 mm, Jan. 0
mm, Feb. 1,2 mm, Mar. 8,9 mm.
The rate of photosynthesis (µMo! co2 m- 2s· 1), stomata!
conductance (mMol m 2 s- 1) and the rate of transpiration (mMol
m- 2 s- 1) were measured using an ADC portable photosynthesis
meter (Analytical Development Co. Ltd., England). The
characteristics of this apparatus are described by Hunter &
Visser (1988c). Radiant energy, expressed as photosynthetic
photonfluence rate (PPFR), was measured using a Li-cor Line
Quantum Radiometer (Li l 188B). Five measurements per
vine of five representative vines per plot were recorded. The
radiometer was inserted in the canopy at cluster height in line
with the cordon. The leaf temperature of four leaves for each
of two representative vines per treatment plot was measured
using a data logger with fixed thermocouples.
A pressure chamber (Scholander et al., 1965) was used to
measure leaf water potential on a 12-hour cycle. Shaded
leaves in the same position in the canopy were used. All the
above mentioned measurements, except those for leaf-water
potential, were recorded at two-hour intervals, starting at
07 :00 and ending at 17 :00 on every day on which recordings
were done. Leaf-water potential was also recorded at twohour intervals, but started at 06:00 and ended at 18:00. These
days were selected to coincide with flowering, pea size,
veraison and ripeness.
The leaf area per vine was calculated 'from measurements
of the total leaf area of five shoots from 10 selected vines per
treatment plot. Canopy density was measured using the point
quadrat method (Smart, 1988). Thirty probes per vine for five
selected vines per plot were recorded at ripeness. Vineyard
scoring was done during veraison using the score card as
suggested by Smart ( l 987b ). The total length per shoot of
three representative shoots for each of five representative
vines per treatment plot was measured at weekly intervals
starting one week after budburst until ripeness (when a sugar
concentration of ca. 23 °B was reached).
S. Afr. J. Enol. Vitic., Vol. 11, No. 2, 1990
Vine Spacing and Physiology
78
Data processing: Where applicable, all data sets were
subjected to a standard two-way analysis of variance (Snedecor
& Cochran, 1967).
the season progressed. This will be further discussed under
"canopy characteristics". In general, for all phenological stages,
PPFR was relatively low in the early morning, rose to a peak
during mid-morning, decreased at midday, rose to a second
peak during mid-afternoon, and decreased again towards late
afternoon. These trends are in accordance with results quoted
by Champagnol (1984) for north-south row orientations. As
the season progressed, the differences in PPFR between
treatments became more pronounced. Vines in the more
closely spaced treatment plots had higher PPFR values than
those in the more wide! y spaced treatment plots. This difference
was more pronounced from pea size to ripeness than earlier in
the season and was probably caused by the more favourable
canopy characteristics of more closely spaced vines. The
highest PPFR was obtained with 2,0 m x 1,0 m vine spacing,
whereas that of the 3,0 m x 3,0 m, 3,0 m x 1,5 m and 2,0 m x
2,0 m spacing was significantly lower. The relatively low
values recorded at midday for all treatments were ascribed to
the position of the sun, it being directly above the north-south
rows at that time of the day. The peak values at mid-morning
and mid-afternoon were caused by a more favourable angle of
incident light for the north-south oriented canopies of the trial.
RES ULTS AND DISCUSSION
Leaf temperature: Although no significant differences
between the leaf temperatures of the different vine-spacing
treatments could be found (Table 2), certain tendencies occurred. The leaves of more closely spaced vines seemed to be
cooler than those of more wide! y spaced vines at the beginning
of the season, whereas this tendency was reversed towards the
end of the season. It is postulated that this tendency occurred
because of the lower canopy density of more closely spaced
vines enabling better air movement through the canopy at the
beginning of the season. During this period vines were also
well supplied with water. As the season progressed the higher
water stress in more closely spaced vines (Archer & Strauss,
1989b) overrode the cooling effect of air movement, resulting
in higher leaf temperatures because stomata! conductance
decreased. This may be the reason why the leaf temperature
of more closely spaced vines rose as the season progressed,
whereas that of more widely spaced vines more or less
stabilized. Peak values of more than 30°C were frequently
measured at midday (Table 3), and these high temperatures
were probably detrimental to stomata! conductance (Heath &
Orchard, 1957) and photosynthesis (Kriedemann, 1968).
Canopy characteristics: The canopy of each treatment
plot was scored twice from both sides prior to ripeness, using
the vineyard scorecard (Smart, l 987b) and the results are
presented in Table 4. As indicated by the scorecard, the
canopies of the more closely spaced treatments showed a
higher potential for producing quality grapes than those of the
more widely spaced treatments. It would appear that a more
favourable microclimate existed in the canopies of the more
closely spaced vines than in those of the more widely spaced
vines. These differences in the canopy characteristics explain
why more favourable radiant energy levels was measured in
the more closely spaced treatment plots.
Radiant energy (PPFR): PPFR values, measured at cluster level within the canopy, ranged from 131 m E ffi" 2 s· 1 for the
2,0 m x 1,0 m treatment at ripeness to 4 m E ffi" 2 s· 1 for the 2,0
m x 2,0 m treatment at flowering and are given in Fig. 1. The
amount of radiant energy intercepted by the canopy appeared
to increase from flowering to veraison. The changes in the
pattern of radiant energy interception were probably caused
by changes in canopy density and the movement of the sun as
The main differences in the canopies of the different
TABLE2
The effect of vine spacing on the mean maximum leaf temperature during flowering, pea size, veraison and ripeness, 1988/89.
Phenological
stage
Flowering
Pea size
Veraison
Ripeness
Mean maximum leaf temperature (°C)
Ambient
temperature
(oC)
1,0 x 0,5
1,0 x 1,0
2,0 x 1,0
2,0 x 2,0
3,0 x 1,5
3,0 x 3,0
31,3
32,7
29,8
33,6
26,3
28,2
29,1
29,5
26,8
28,0
29,3
29,2
26,9
28,4
28.9
29,0
26,9
28,7
28,6
28,8
27,2
28,8
28,8
28,5
27,5
29,4
28,0
27,3
TABLE3
The effect of vine spacing on maximum leaf temperature during flowering, pea size, veraison and ripeness, 1988/89.
Phenological
stage
Flowering
Pea size
Veraison
Ripeness
Mean leaf temperature (°C)
1,0 x 0,5
1,0 x 1,0
2,0 x 1,0
2,0 x 2,0
3,0 x 1,5
3,0 x 3,0
32,9
35,1
35,3
38,7
32,5
34,9
35,0
37,8
33,0
34,6
36,0
36,7
31,8
34,4
35,9
37,3
31,0
33,9
34,7
37,0
32,4
35,1
34,7
36,9
s. Afr. J. Enol. Vitic., Vol. 11, No. 2, 1990
250
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FIGURE 1
The effect of vine spacing on the radiant energy received at cluster level within the canopy of Pinot noir/99 Richter during flowering, pea size, veraison and ripeness.
'-.}
\Q
80
TABLE4
The effect of vine spacing on canopy characteristics of Pinot noir/99 Richter prior to ripeness, evaluated by means of vineyard
scorecard (Smart, 1987b ).
Vine spacing
Parameter
(ex 10)
D-value
(p:::; 0,05)
1,0 x 0,5 m
l,Ox l,Om
2,0 x 1,0 m
Canopy gaps
Leaf size
Leaf colour
Canopy density
Fruit exposure
Shoot length
Lateral growth
Growing tips
8,0
9,6
9,5
8,5
10,0
10,0
10,0
10,0
8,5
9,2
9,6
8,0
10,0
10,0
10,0
10,0
9,2
9,0
9,6
4,8
8,0
6,8
9,5
10,0
6,5
8,0
9,0
2,0
6,0
6,0
2,0
4,0
6,0
7,2
8,5
2,0
2,0
2,0
2,0
4,0
6,0
6,8
8,0
2,0
4,0
2,0
6,0
6,0
2,3
ns
ns
2,5
4,1
3,2
4,8
3,4
TOTAL
(as percentage)
94,5
94,l
83,6
54,4
42,1
51,0
28,03
2,0 x 2,0 m
treatment plots occurred with canopy gaps, canopy density,
fruit exposure, shoot length, the amount of lateral growth and
the number of growing tips present. Furthermore, the shoots
of more widely spaced vines grew actively during the period
veraison to ripening (Fig. 2). In addition, these shoots were
characterized by more pronounced lateral growth (Table 4)
with subsequent higher canopy density and less exposed fruit
than in the case of the more closely spaced treatment plots. It
is postulated that the higher rate of soil water depletion, which
3,0 x 3,0 m
was induced by the higher root density of closer spacings
(Archer & _Strauss, l 989b), gave rise to an earlier arrestment
of shoot growth.
Canopy density was also measured with the point quadrat
method (Smart, 1988), and the results are given in Table 5.
These results verify the visual results in Table 4 and show that
the canopies of more closely spaced vines were less dense than
those of more widely spaced vines. The more favourable
canopy characteristics of more closely spaced vines possibly
3.0m x 3.0m
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FIGURE 2
The effect of vine spacing on untrimmed shoot growth of Pinot noir/99 Richter grapevines.
S. Afr. J. Enol. Vitic., Vol. 11, No. 2, 1990
16
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FIGURE 3
The effect of vine spacing on the daily leaf-water potential during flowering, pea size, veraison and ripeness of Pinot noir/99 Richter grapevines.
.._
Oo
Vine Spacing and Physiology
82
had a positive effect on the quantity and quality of the fruit
produced; this will be discussed in a later publication.
closely spaced vines being more stressed during veraison and
ripeness than more widely spaced vines (Fig. 4). These results
correspond well with those reported by Archer & Strauss
(1989b).
TABLES
Stomatal conductance: The stomata! conductance values, which varied from 400 mMol rn- 2 s· 1 for sunlit leaves at
pea size to 40 mMol rn- 2 s· 1 for shaded leaves at ripeness are
presented in Fig. 5. In general, over all phenological stages,
stomata] conductance for sunlit leaves was relatively low
early in the morning, at midday and in the late afternoon, with
two distinguishable peaks occurring during mid-morning and
mid-afternoon. These results coincide with those of Downton,
Grant & Loveys (I 987). In the case of shaded leaves, stomata!
conductance reached a peak in the middle of the day. These
trends are in accordance with results quoted by Champagnol
(1984). Stomata] conductance appeared to increase from
flowering to pea size while soil water was still adequate, but
apparently decreased from pea size to ripeness (Fig. 5) as a
higher plant-water stress was induced by the depletion of soil
water (Archer & Strauss, I 989b ). Little differences in stomata!
conductance occurred during the early part of the season
between vines planted to different spacings, but during the
ripening process (veraison to ripeness) more closely spaced
vines experienced a significantly lower conductance than
more widely spaced vines. This was probably caused by a
higher induced plant-water stress in the case of narrow spacings
(Archer & Strauss, l 989b) and is in accordance with results
obtained for heat-stressed Chenin blanc vines by Sepulveda &
Kliewer ( 1986). The lowest stomata! conductance was obtained in vines with a spacing of 1,0 m x 0,5 m and 1,0 m x 1,0
The effect of vine spacing on the leaf layer number of Pinot
noir/99 Richter grapevines.
Vine spacing (m)
1,0
1,0
2,0
2,0
3,0
3,0
Leaf layer number
x 0,5
x 1,0
x 1,0
x 2,0
x 1,5
x 3,0
1,15
1,88
2,60
3,73
5,75
6,50
D-value (p ~ 0,01)
2,091
Leaf-water potential: The daily leaf-water potential during the various phenological stages (flowering, pea size,
veraison and ripeness), as affected by vine spacing, is depicted
in Fig. 3 whereas the mean daily values are shown in Fig. 4.
During the day, peak values were measured between 12:00
and 14:00, which is in accordance with results presented by
Champagnol (1984), Van Zyl (1984) and Archer & Strauss
( 1989). Although predawn values were similar during the
early part of the season, larger differences occurred during
veraison and ripeness (Fig. 3). More closely spaced vines
endured less water stress during the early part of the season
(Fig. 4). At about pea size this tendency was reversed, more
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RIPENESS
PHENOLOGICAL STAGES
FIGURE4
The effect of vine spacing on the mean daily leaf-water potential during flowering, pea size, veraison and ripeness of Pinot
noir/99 Richter grapevines.
S. Afr. J. Enol. Vitic., Vol. 11, No. 2, 1990
480
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FIGURES
The effect of vine spacing on the daily stomata! conductance during flowering, pea size, veraison and ripeness of Pinot noir/99 Richter grapevines.
~
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FIGURE6
The effect of vine spacing on the daily transpiration rate during flowering, pea size, veraison and ripeness of Pinot noir/99 Richter grapevines.
17: 00
85
m, and the highest conductance was recorded with a spacing
of 3,0 m x 3,0 m. Shaded leaves appeared to have contributed
more to the total stomata! conductance in the case of more
closely spaced vines during ripeness (Fig. 5) than in the case
of more widely spaced vines. The decrease in stomata! conductance at midday can probably be ascribed to low leaf-water
potential, induced by high leaf temperature, forcing stomata to
close (Sepulveda & Kliewer, 1986).
Rate of transpiration: The transpiration rate followed a
very similar pattern to that of stomata! conductance. Values
for the rate of transpiration varied from 1,1 mMol m 2 s· 1 at
ripeness to 6,6 mMol m· 2s· 1 at pea size for sunlit leaves (Fig.
6). For shaded leaves this value varied from 0,9 mMol m· 2 s· 1 at
ripeness to 4 mMol m· 2 s· 1 at pea size (Fig 6). Similar to results
obtained by Alleweldt, Eibach & Rtihl ( 1982) as well as Fails,
Lewis & Barden (1982), the rate of transpiration for sunlit
leaves in this trial was relatively lower early in the morning,
at midday and in the late afternoon and reached a peak during
mid-morning as well as during mid-afternoon. For shaded
leaves the rate of transpiration reached a peak during the
middle of the day. These trends are in accordance with results
quoted by Champagnol ( 1984 ). Dictated by stomata! conductance, the rate of transpiration apparently increased from
flowering to pea size for all treatments but decreased from pea
size to ripeness. Although no statistical differences could be
found in the rate of transpiration between different spacings
during the early part of the season, marked differences occurred in both shaded and sunlit leaves during veraison and
ripeness (Fig. 6). At these stages the more closely spaced vines
showed a significantly lower transpiration rate than those in
wider spacings. As with stomata! conductance, this was also
associated with a more negative leaf-water potential in the
case of narrow vine spacings (Fig. 3). The lowest rate of
transpiration was recorded in vines spaced 1,0 m x 0,5 m and
1,0 m x 1,0 m, the highest in vines with a spacing of 3,0 m x
3,0m.
Rate of Photosynthesis: The rate of photosynthesis followed a similar pattern to those of stomata! conductance and
rate of transpiration. Values for the rate of photosynthesis
varied from 1,7 µMo! m 2 s· 1 for shaded leaves at ripeness to
16,5 µMo! m· 2 2 1 for sunlit leaves at pea size (Fig. 7). In
general, over all phenological stages, the rate of photosynthesis for sun leaves was lowest in the early morning and highest
at mid-morning. After declining at midday, a second, somewhat lower, peak was reached during mid-afternoon, after
which the rate declined towards late afternoon. These results
coincide with those found by Downton, Grant & Loveys
( 1987). With shaded leaves, these peaks were not as accentuated
as in the case of sunlit leaves. These trends are in accordance
with results quoted by Champagnol (1984 ). Similarly to
stomata! conductance, the rate of photosynthesis appeared to
increase from flowering to pea size and to decrease from pea
size to ripeness (Fig. 7), as was the case with the rate of
transpiration. This decrease during the latter part of the growing
season can probably be ascribed to an increase in plant-water
stress as was indicated by Archer & Strauss (1989b) and in
Figs. 3 & 4. This decrease agrees with results obtained by
Hofacker ( 1976) and Alleweldt & Rtihl ( 1982). Lower interior
light intensity as well as high leaf temperature at midday,
which induceq lower leaf-water potentials, exerted a negative
effect on the rate of photosynthesis through stomata! movement, and this was evident throughout the growing season.
The decline in the rate of photosynthesis over the growing
season was also reported by Kriedemann ( 1977) and Hunter &
Visser (l 988a, l 988b, l 988c ).
CONCLUSIONS
Under the conditions of this experiment (dry-land, lowpotential soil, vertical trellis), the canopies of more closely
spaced vines were less dense than those of more widely spaced
vines. This was due mainly to the less vigorous shoot growth
induced by intervine competition for soil water and nutrients
in the relatively restricted soil depth. Consequently, fewer and
shorter shoots (restricted budburst and growth of collar buds
and water shoots) and restricted lateral shoot development
occurred in more closely spaced vines. Vines in the more
closely spaced treatment plots thus had a better balance
between shoot growth and yield, which contributed to less
den~e canopies.
The more open canopies of the more closely spaced vines
allowed better penetration of sunlight into the fruit zone,
whereby stomata! conductance, transpiration and photosynthesis were favoured during the early part of the season. As the
season progressed, however, more severe competition for
declining soil water caused an increase in plant-water stress
which was accentuated in the case of more closely spaced
vines. This resulted in a reversal in stomata! conductance,
transpiration and photosynthesis, in respect of which vines in
the more closely spaced treatment plots were less active than
more widely spaced vines during the latter part of the season.
The 2,0 m x 1,0 m spaced vines had thin, open canopies
similar to more closely spaced vines, but the inter-row space
was wider, resulting in better sunlight penetration. Less crossrow shading occurred especially during early to mid-morning
and mid- to late-afternoon. The relatively low values measured
at midday could be ascribed to the sun being directly above the
north-south oriented rows and the measurement being done in
the middle of the canopy at cluster level. The decline at
midday in the rates of stomata! conductance, transpiration and
photosynthesis are probably related to temperature and light.
The physiological activity of grapevines is strongly related
to physical soil properties such as water-holding capacity and
the supplying of water to the vine root. For the soil in this trial,
water uptake by vine roots was dominated mainly by high root
density, which eventually led to the more closely spaced vines
having more open canopy characteristics than the more widely
spaced vines. Under more luxurious conditions (higher soil
potential, irrigation, higher N-nutrition, etc.), decreased water
stress might cause stronger shoot growth, resulting in different
canopy characteristics. This will probably lead to wider
spacings obtaining less dense canopies than closer spacings.
It is postulated that more fertile conditions will need wider inrow spacings to achieve optimal yield and quality than was"the
case with more closely spaced vines in this trial.
Vine physiology, as affected by vine spacing, will affect
the growth, yield and quality of Pinot noir grapes. These
aspects require further investigation.
S. Afr. J. Enol. Vitic., Vol. 11, No. 2, 1990
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FIGURE 7
.
. d unng
. flowering ' pea size, veraison and ripeness of Pinot noir/99 Richter grapevmes.
The effect of vine spacing on the rate of photosynt hes1s
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Vine Spacing and Physiology
LITERATURE CITED
ALLEWELDT, G. & RUHL, E., 1982. Investigations on gas exchange in
grapevine II. Influence of extended soil drought on perfonnance of
several grape-vine varieties. Vitis 21, 313-324.
ALLEWELDT, G., EIBACH, R. & RUHL, E., 1982. Investigations on gas
exchange in grape-vine I. Influence of temperature, leaf age and daytime
on net photosynthesis and transpiration. Vi tis 21, 93-100.
ARCHER, E., 1987. The role of light and canopy management in South
African vineyards. Deciduous Fruit Grower 37, 397-405.
ARCHER, E. & BEUKES, A.J., 1983. Suicr van wyndruiwc. Die Wynhoer
624, 79-81.
ARCHER, E. & FOUCHe, G.W., 1987. Effect of bud load and rootstock
cultivar on the perfonnance of V. rinifera L. cv. Red Muscadcl (Muscat
noir). S. Afi· . .!. Eno/. Vitic. 8, 6-10.
ARCHER, E. & STRAUSS, H.C., l 989a. Effect ofshadingon thepe1fom1ance
of Vi tis l'inifera L. cv. Cabernet Sauvignon. S. Afr . .!. Eno/. \Ii tic 10, 7477.
ARCHER, E. & STRAUSS, H.C., l 989b. The effect of plant spacing on the
water status of soil and grapevines. S. Afi-. J. Eno/. Vi tic. 10, 49-58.
BIDWELL, R.G.S., 1974. Planl Physiology. Macmillan Publishing Co .. New
York.
BLEDSOE. A.M., KLIEWER, W.M. & MAROIS, J.J .. 1988. Effects of
timing and severity of leaf removal on yield and fruit composition of
Sauvignon blanc grapevines. Am. J. Eno/. Vitic 39, 49-54.
BONIFACE. J.C. & DUMARTIN, P., 1977. Effects du rognage et de
J'effeuillage sur la qualite de la vendage. \lignes & Vins 258, 5-10.
BOSWELL, S.B., NAUER, E.M. & ATKIN, D.R., 1982. Effect of tree
density on fruit quality, temperature. light penetration, growth and production of old-line "Atwood" navel orange trees. J. Am. Soc. Horr. Sci.
107, 60-65.
CARBONNEAU, A., LECLAIR, P .. DUMARTIN, P., CORDEAU, J. &
ROUSSEL, C., 1977. Regularisation de la production el de la qualite des
vins rouges par le rognage, l'effeuillage et l'eclaircissagc. \lignes & \!ins
256, 19-27.
CHAMPAGNOL, F., 1984. Elements de physiologic de la vigne et de
viticulture generale. F. Champagnol. B.P. 13 Prades-le-Lez, 34980 SaintGely-du-Fesc, France.
DOWNTON, W.J.S., GRANT, W.J.R. & LOVEYS. B.R.. 1987. Diurnal
changes in the photosynthesis of field-grown grapevines. New Phytol.
105, 71-80.
FAILS, B.S., LEWIS, A.J. & BARDEN, J.A., 1982. Net photosynthesis and
transpiration of sun- and shadegrown Ficus henjamina leaves . ./. Amer.
Soc. Hort. Sci. 107, 758-761.
FARQUHAR, G.D. & SHARKEY, T.D., 1982. Stomata! conductance and
photosynthesis. Ann. Rel'. Flam Physiol. 33, 317-345.
87
KRIEDEMANN, P.E., 1968. Photosynthesis in vine leaves as a function of
light intensity, temperature, and leaf age. Viti.1· 7, 213-220.
KRIEDEMANN, P.E., 1977. Vine leaf photosynthesis. In: Proc. Int. Symp. on
the Quality of the Vintage, 14-21 Feb. Cape Town, 67-87.
KRIEDEMANN, P.E. & SMART, R.E., 1971. Effects ofirradiance, temperature and leaf water potential on photosynthesis of vine leaves.
Photosymhetica 5, (I), 6-15.
MORGAN, D.C.. STANLEY, C.J. & WARRINGTON, I.J., 1985. The
effects of simulated daylight and shade-light on vegetative and reproductive growth in kiwifruit and grapevine . .!. Hort. Sci. 60, 473-484.
PETERSON, J.R. & SMART, R.E., 1975. Foliage removal effects on Shiraz
grapevines. Am. J. Eno/. \litic 26, 119-124.
REYNOLDS, A.G., 1989. Riesling grapes respond to cluster thinning and
shoot density manipulation . .!. Amer. Soc. Hort. Sci. I 14, 364-368.
REYNOLDS, A.G., & WARD LE, D.A., 1989. Effects of timing and severity
of summer hedging on growth, yield, fruit composition and canopy
characteristics of de Chaunac I. Canopy characteristics and growth
parameters. Am . .!. Eno/. Vitic 40, 109-120.
REYNOLDS. A.G., POOL, R.M. & MATTICK, L.R., 1986. Effect of shoot
density and crop control on growth, yield, fruit composition, and wine
quality of Scyval blanc grapes. J. Amer. Soc. Hort. Sc_i. 111, 55-63.
SCHOLANDER, P.F., HAMMEL, H.T., BRADSTREET, E.D. &
HEMMINGSON, E.A., 1965. Sap pressure in vascular plants. Science
148, 339-346.
SEPULVEDA, G. & KLIEWER, W.M., 1986. Stomata! response of three
grapevine cultivars (Viti.1· vi11ifera L.) to high temperature. Am . .!. Eno/.
\iitic. 37, 44-52.
SHAULIS. N., AMBERG, H. & CROWE, D., 1966. Response of Concord
grapes to light exposure and Geneva Double Curtain training. Proc. Amer.
Soc. Hort. Sci. 89, 268-280.
SMART, R.E., 1974. Photosynthesis by grapevine canopies..!. appl. Ecol.11,
997-1006.
SMART, R.E., 1985. Principles of grapevine canopy microclimate manipulation with implications for yield and quality. A review. Am . .!. Eno/. Vi tic.
36, 230-239.
SMART, R.E., l 987a. Influence of light on composition and quality of
grapes. Acla Horticulturae 206, 37-47.
SMART, R.E., 1987b. Canopy management to improve yield, fruit composition and vineyard mechanisation. A review. In: T.H. Lee (Ed.), Proc. 6th
Aus tr. Wine Ind. Tech. Conf., 14-17 July 1986, Adelaide, South Australia,
A.W.R.l., Adelaide. 205-211.
SMART, R.E., 1988. Shoot spacing and canopy light microclimate. Am . .!.
Eno/. \litic. 39, 325-333.
SMART, R.E. & SINCLAIR, T.R., 1976. Solar heating of grape berries and
other spherical fruit. Agric. Meteorol. 17. 241-259.
HEATH, O.V.S. & ORCHARD, B., 1957. Midday closure of stomata. nature
180, 180-181.
SMART, R.E., ROBINSON, J.B., DUE, G.R. & BRIEN, C.J., I 985a. Canopy
microclimate modification for the cultivar Shiraz I. Definition of canopy
microclimate. Vitis 24, 17-31.
HEDEBERG, P.R. & RAISON, J., 1982. The effect of vine spacing and
trellising on yield and fruit quality of Shiraz grapevines.Am..!. Eno/. \litic.
33, 20-30.
SMART, R.E..ROBINSON, J.B., DUE, G.R. &BRIEN, C.J., I 985b. Canopy
microclimate modification for the cultivar Shiraz II. Effects on must and
wine composition. \!iris 24, 119-128.
HOFACKER, W., 1976. Investigations on the influence of changing soil
water supply on the photosynthesis intensity and the diffusive resistance
of vine leaves. \litis 15, 171-182.
SMART, R.E, SMITH, S.M. & WINCHESTER, R.V., 1988. Light quality
and quantity effects on fruit ripening forCabemet Sauvignon.Am . .1. Eno/.
Vitic. 39, 250-258.
HUNTER, J.J. & VISSER, J.H., I 988a. Distribution of 14C-photosynthetate
in the shoot of\litis vinifera L. cv. Cabernet Sauvignon I. The effect ofleaf
position and developmental stage of the vine. S. Afr. J. Eno/. \Ii tic. 9( I),
3-9.
SNEDECOR, G.W. & COCHRAN, W.G., 1967. Statistical methods (6th
edition). Iowa State Univ. Press, Ames, Iowa, USA.
HUNTER, J.J. & VISSER, J.H., 1988 b_, Distribution of 14 C-photosynthetate
in the shoot of \litis vinifera L. cv. Cabernet Sauvignon II. The effect of
pa11ial defoliation. S. Afr . .!. Eno/. \litic. 9(1), 10-15.
SPARKS, D. & LARSEN, R.P., 1966. Effect of shading and leaf area on fruit
soluble solids of the Concord grape, \litis Lahrusca L. Proc. Amer. Soc.
Hort. Sci. 89, 259-267.
VANZYL, J.L., 1984. Interrelationships among soil water regime, irrigation
and water stress in the grapevine (\litis 1·inifera L.) Ph.D. Agric-dissertation, Univ. Stellenbosch, 7600 Stellenbosch, RSA.
HUNTER, J.J. & VISSER, J.H., l 988c. The effect of partial defoliation, leaf
position and developmental stage of the vine on the photosynthetic
activity of\litis vin!fera L. cv. Cabernet Sauvignon. S. Afr . .!. Eno!. \litic.
9 (2), 9-15.
WILLIAMS, L.E., BISCAY, P.J. & SMITH, R.J., 1987. Effect of interior
canopy defoliation on berry composition and potassium distribution in
Thompson Seedless grapevines. Am . .!. Eno/. Vitic. 38, 287-292.
KLIEWER, W.M., 1982. Vineyard canopy management -A review. In: (ed)
A.O. Webb. Proc. Grape and Wine Cent. Symp., 18-21June1980, Univ.
Calif. Davis. 342-351.
ZEEMAN, A.S., 1981. Oplei. In: J. Burger & J. Deist (Eds), Wingerdbou in
Suid-Afrika. V.O.R.I. Private Bag X5026, 7600 Stellenbosch, RSA 185201.
S. Afr. J. Encl. Vitic., Vol. 11, No. 2, 1990