Abstract
Vitis vinifera (L.) cv. Shiraz commonly loses a significant amount of bunch water during late ripening, with attendant yield losses. The objective of the study was to quantitatively assess the hypothesis that this sustained weight loss was due to decreased vascular flow and increased transpiration. Transpiration, fresh and dry weights, and water content of whole attached grape bunches were measured from flowering to maturity on vines grown in controlled environments and in the vineyard. Seasonal changes in net water fluxes into and out of bunches were determined. A simple technique of weighing bunches in situ also provided independent measurement of daily rates of water gain and loss. Bunch transpiration rates were high just after flowering but declined to 0.2 g g (dry wt)−1 d−1 at about harvest date. Bunch net water import rates also showed a 90% decrease with development from 1.0 to 0.1 g g (dry wt)−1 d−1. Comparisons of these rates revealed net water import exceeded transpiration throughout early and midbunch development. However, at 60 to 80 days after flowering, import rates had declined to an extent that transpiration now exceeded import and an overall loss of water occurred. Quantitatively comparable rates of water gain and loss determined on Shiraz bunches over four growing seasons on vineyard-grown vines conformed closely with those rates determined as above. Changes in diurnal bunch water fluxes supported the conclusion that net water import exceeded transpiration losses throughout bunch development until the late stage of ripening. The hypothesis that sustained weight loss in late-ripening Shiraz grape bunches occurred because bunch water fluxes shifted from a net import to a net loss by transpiration was confirmed.
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Claims 7
Claim · model-written summary
Bunch transpiration declined to 0.2 g g (dry wt)−1 d−1 near harvest.
- Taxon
- Vitis vinifera
Vitis viniferat0 - Organ / stage
- harvest datee0
- Outcome
- Bunch transpiration ratese0
- Direction
- declinede0
- Value
- 0.2 g g (dry wt)−1 d−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“Bunch transpiration rates were high just after flowering but declined to 0.2 g g (dry wt)−1 d−1 at about harvest date”
Claim · model-written summary
Net bunch water import declined 90% during development from 1.0 to 0.1 g g (dry wt)−1 d−1.
- Taxon
- Vitis viniferaVitis viniferat0
- Outcome
- Bunch net water import ratese0
- Direction
- decreasee0
- Value
- 90%e0
- Qualifier
- from 1.0 to 0.1 g g (dry wt)−1 d−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“Bunch net water import rates also showed a 90% decrease with development from 1.0 to 0.1 g g (dry wt)−1 d−1”
Claim · model-written summary
Net water import exceeded transpiration during early and mid bunch development.
- Taxon
- Vitis viniferaVitis viniferat0
- Organ / stage
- early and midbunch developmente0
- Outcome
- net water importe0
- Direction
- exceedede0
- Comparator
- transpiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“net water import exceeded transpiration throughout early and midbunch development”
Claim · model-written summary
At 60 to 80 days after flowering, transpiration exceeded import and bunches lost water overall.
- Taxon
- Vitis viniferaVitis viniferat0
- Organ / stage
- 60 to 80 days after floweringe0
- Outcome
- overall loss of watere0
- Direction
- losse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“at 60 to 80 days after flowering, import rates had declined to an extent that transpiration now exceeded import and an overall loss of water occurred”
Claim · model-written summary
Vineyard measurements over four seasons closely matched controlled environment water gain and loss rates.
- Taxon
- Vitis viniferaVitis viniferat0
- Outcome
- rates of water gain and losse0
- Comparator
- those rates determined as abovee0
- Setting
- vineyard-grown vinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“Quantitatively comparable rates of water gain and loss determined on Shiraz bunches over four growing seasons on vineyard-grown vines conformed closely with those rates determined as above”
Claim · model-written summary
Diurnal water flux observations supported net import exceeding transpiration until late ripening.
- Taxon
- Vitis viniferaVitis viniferat0
- Organ / stage
- late stage of ripeninge0
- Outcome
- net water importe0
- Direction
- exceedede0
- Comparator
- transpiration lossese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera”
e0“Changes in diurnal bunch water fluxes supported the conclusion that net water import exceeded transpiration losses throughout bunch development until the late stage of ripening”
Claim · model-written summary
Late Shiraz bunch weight loss was attributed to a shift from net water import to transpiration loss.
Verbatim
e0“sustained weight loss in late-ripening Shiraz grape bunches occurred because bunch water fluxes shifted from a net import to a net loss by transpiration”