Articles
THE INFLUENCE OF CONTROLLED WATER INPUTS ON GRAPE QUALITY IN REGIONS OF AUSTRALIA WITH HOT MEDITERRANEAN CLIMATES
Article number
582_8
Pages
101 – 107
Language
English
Abstract
Management, trellis and pruning systems that increase the ratio of leaves to
fruit and the exposure of leaves and fruit to sunlight are inputs that that are well
known to contribute to the improvement of grape quality when combined with moder-ate
cropping levels.
However two irrigation systems regulated deficit irrigation (RDI)
and partial root zone drying (PRD) are now available in the regions of Australia with
warm dry summers typical of Mediterranean countries which are able to modify the
vegetative and reproductive growth of grapevines and significantly improve the qual-ity
of grapes for wine making.
Initial experiments involving the application of RDI to
grapevines began in the late 1980s and involve reducing vine water inputs during the
early stages of bunch development after flowering and fruit set are complete.
RDI can
reduce both bunch and berry size, and increase soluble solids, colour and aroma.
When
applied properly RDI improves fruit quality but has the potential to significantly de-crease
yield.
It is effective in regions with limited spring rain where soil moisture ten-sions
in the vine root zone reach and can be maintained in the range 200400 kPa for
heavy (clay) soils and 5080 kPa for sands.
RDI may contribute to salinity problems
where soils and irrigation waters are high in salt.
PRD is a novel irrigation technique
of great potential importance to Australian viticulture and is applicable to a range of
other horticultual crops.
In PRD, water is given to half the vine root system for a 10
to14 day period using appropriately placed drippers and at the end of this period the
other half of the root system is irrigated using an independently supplied dripper line.
At any one time only about half of the roots of the vine receive water which signifi-cantly
reduces the overall requirement for irrigation water.
PRD reduces both vine
vigour and canopy density, and improves the quality of red varieties by raising the
levels of berry anthocyanins through better bunch exposure.. It does not markedly
reduce yield.
The PRD effect is not an hydraulic one, but is due to chemical signals
translocated from the dry roots which induce only partial closing of stomata and re-duce
both shoot and leaf growth..
fruit and the exposure of leaves and fruit to sunlight are inputs that that are well
known to contribute to the improvement of grape quality when combined with moder-ate
cropping levels.
However two irrigation systems regulated deficit irrigation (RDI)
and partial root zone drying (PRD) are now available in the regions of Australia with
warm dry summers typical of Mediterranean countries which are able to modify the
vegetative and reproductive growth of grapevines and significantly improve the qual-ity
of grapes for wine making.
Initial experiments involving the application of RDI to
grapevines began in the late 1980s and involve reducing vine water inputs during the
early stages of bunch development after flowering and fruit set are complete.
RDI can
reduce both bunch and berry size, and increase soluble solids, colour and aroma.
When
applied properly RDI improves fruit quality but has the potential to significantly de-crease
yield.
It is effective in regions with limited spring rain where soil moisture ten-sions
in the vine root zone reach and can be maintained in the range 200400 kPa for
heavy (clay) soils and 5080 kPa for sands.
RDI may contribute to salinity problems
where soils and irrigation waters are high in salt.
PRD is a novel irrigation technique
of great potential importance to Australian viticulture and is applicable to a range of
other horticultual crops.
In PRD, water is given to half the vine root system for a 10
to14 day period using appropriately placed drippers and at the end of this period the
other half of the root system is irrigated using an independently supplied dripper line.
At any one time only about half of the roots of the vine receive water which signifi-cantly
reduces the overall requirement for irrigation water.
PRD reduces both vine
vigour and canopy density, and improves the quality of red varieties by raising the
levels of berry anthocyanins through better bunch exposure.. It does not markedly
reduce yield.
The PRD effect is not an hydraulic one, but is due to chemical signals
translocated from the dry roots which induce only partial closing of stomata and re-duce
both shoot and leaf growth..
Authors
J.V. Possingham
Keywords
Vitis vinifera, irrigation, regulated deficit irrigation, partial root zone drying
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