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Fruit dry matter (%)
Soluble solids content (%)
Irrigation treatment Fruit weight(g) Dry matter(%) Soluble solid content(%) TZG Yield(TE/ha) OGR($/ha)
Full-irrigation 101.2 a 17.36 a 5.77 a 0.552 8,400 $38,200
Half-irrigation 97.8 b 17.77 a 6.05 a 0.613 8,000 $35,300
Quarter-irrigation 92.3 c 18.95 b 6.63 b 0.764 7,200 $31,300
Table 2. Effects of irrigation treatments at a Gisborne Hayward orchard on fruit attributes in March/April 2007 (n=3 plots).
Means in a column with the same letter are not signifi cantly different at P=0.05 (LSD).
TE = tray equivalents, TZG = Taste ZESPRI grade, OGR = estimated orchard gate return (gross return less postharvest costs, based on $3.72/TE fruit payment, TZG
payments based on maximum $1.88/TE, KiwiStart incentive payments for week 14 based on $1.45/TE and postharvest costs of $2.95/TE).
Figure 6. Changes in Gisborne Hayward fruit weight, dry matter and soluble solids of fruit from full-irrigation and defi cit irrigation treatments in 2007.
weight (seven per cent). It is likely that
although leaf function (photosynthesis)
would have been reduced under the water
defi cits, root demand for carbohydrates
may also have been reduced, resulting in a
higher proportion of photosynthates going
to the fruit.
RE-IRRIGATING DRY VINES HAD
MINIMAL IMPACT CLOSE TO
HARVEST
There was some evidence that re-irrigating
the vines in April had only a small impact
on dry matter of fruit from defi cit-irrigated
vines (Figure 6). The impact of this late
irrigation was to reduce dry matter
accumulation of fruit from quarter-irrigation
vines by 0.2 per cent-units, relative to fullirrigation,
although this effect could not be
determined with any statistical confi dence
Mean fruit weight (g)
Predicted incidence of fruit
within our experimental design. Even if this
were the case, the shift was very small and
would have had little effect on orchard
returns. These results are consistent with a
study conducted in 2005, where the
impacts of heavy rainfall close to harvest
were found to be quite small (Currie &
Nicholls 2006). Both results strongly
suggest that kiwifruit growers need not be
concerned that sampling or harvesting soon
after rainfall or irrigation will result in reduced
fruit dry matter.
FRUIT FROM WATER DEFICIT
TREATMENTS STORED WELL
Although fruit at this orchard were suitable
for early supply, when we stored fruit
harvested in early April, the rate of fruit
softening in cold storage or after shelf
storage at 20°C was not accelerated by
defi cit irrigation. In fact there was some
evidence that fruit from defi cit-irrigated
plots maintained a higher fi rmness for
much longer. Alternatively, it is possible that
fruit from fully irrigated vines actually
softened faster than ideal. Although this
study does not replicate fully the impacts of
handling and storage that would otherwise
occur in commercial postharvest systems,
the results do not identify any risk that
defi cit irrigation would lead to poor storage
of early harvested fruit. However, impacts
that defi cit irrigation might have on
advancing fruit maturation would need to
be considered when scheduling harvests.
Clearance to pick could be obtained at an
earlier date for early harvest windows.
However, if fruit were harvested late in the
season, it is possible that they could
become over-ripe and thus less suitable for
long-term storage.