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 per g dry weight per day by harvest.
- Taxon
- Vitis vinifera L. cv. Shiraz
Vitis viniferat0 - Outcome
- Bunch transpiration ratese0
- Direction
- declinede0
- Value
- 0.2 g g (dry wt)-1 d-1e0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
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 decreased 90% with development.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Outcome
- Bunch net water import ratese0
- Direction
- decreasee0
- Value
- 90%e0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
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 in early and mid bunch development.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Organ / stage
- bunche0
- Outcome
- net water importe0
- Direction
- exceedede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
e0“net water import exceeded transpiration throughout early and midbunch development”
Claim · model-written summary
From 60 to 80 days after flowering, transpiration exceeded import and bunch water was lost.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Outcome
- overall loss of watere0
- Direction
- losse0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
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
In situ vineyard measurements over four seasons closely matched prior water gain and loss rates.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Organ / stage
- bunche0
- Outcome
- rates of water gain and losse0
- Direction
- conformed closelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
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
Net import exceeded transpiration losses until late ripening.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Organ / stage
- bunche0
- Outcome
- net water importe0
- Direction
- exceedede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
e0“net water import exceeded transpiration losses throughout bunch development until the late stage of ripening”
Claim · model-written summary
Sustained late ripening bunch weight loss was attributed to a shift from net import to transpiration driven water loss.
- Taxon
- Vitis vinifera L. cv. ShirazVitis viniferat0
- Organ / stage
- bunche0
- Outcome
- sustained weight losse0
- Direction
- losse0
- Qualifier
- bunch water fluxes shifted from a net import to a net loss by transpiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Shiraz”
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 was confirmed”