Abstract
Effects of soil water depletion level and irrigation cut off during ripening on water stress in Sunred Seedless table grapes were studied in a field trial in the Hex River Valley of South Africa. Water status of grapevines subjected to four irrigation treatments was determined prior to harvest during the 2000/01 season. Grapevines of all treatments were irrigated at 40% plant available water (PAW) depletion before véraison. From véraison, i.e. the onset of ripening in December, until harvest at the end of January, two treatments were irrigated at 20% and 40% PAW depletion, respectively. Two more treatments were applied by cutting off irrigation at 20% PAW depletion when total soluble solids reached 12°B and 15°B, respectively. Pre-dawn water stress in grapevines irrigated at 20% PAW depletion until harvest was less than in those where irrigation was cut off at 12°B. Sap flow measurements indicated that partial stomatal closure seemed to have occurred over the warmest part of the day. Apparently, stomatal control limited Ψl differences between treatments although extensive soil water depletion occurred where irrigation was cut off during ripening. If accumulated leaf water potential (ΨT) is considered, irrigation cut off at 12°B and 15°B induced more water stress in grapevines from 04:00 to 24:00 compared to those vines where irrigation was continued until harvest. Where irrigation was continued throughout the ripening period, the level of PAW depletion did not affect ΨT. However, during the sunshine period (08:00 until 18:00), ΨT in grapevines subjected to 40% PAW depletion, as well as those where irrigation was cut off, was higher than in the ones that were irrigated at 20% depletion until harvest. During the first half of the night, i.e. from 18:00 until 24:00, water potential in grapevines where irrigation was cut off at 12°B was unable to recover to the same level as in those exposed to the other treatments.
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Claims 7
Claim · model-written summary
Irrigation cut-off at 12°B and 15°B induced more water stress in grapevines from 04:00 to 24:00 than continued irrigation.
- Material
- Sunred Seedlesse0
- Treatment
- irrigation cut off at 12°B and 15°Be4
- Outcome
- water stresse4
- Direction
- moree4
- Qualifier
- from 04:00 to 24:00e4
- Comparator
- those vines where irrigation was continued until harveste4
- Setting
- Hex River Valley of South Africae0
VitisOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Effects of soil water depletion level and irrigation cut off during ripening on water stress in Sunred Seedless table grapes were studied in a field trial in the Hex River Valley of South Africa”
e4“If accumulated leaf water potential (ΨT) is considered, irrigation cut off at 12°B and 15°B induced more water stress in grapevines from 04:00 to 24:00 compared to those vines where irrigation was continued until harvest”
Claim · model-written summary
Pre-dawn water stress was lower in grapevines irrigated at 20% PAW depletion until harvest than in those with irrigation cut off at 12°B.
- Treatment
- irrigated at 20% PAW depletion until harveste1
- Outcome
- Pre-dawn water stresse1
- Direction
- lesse1
- Comparator
- irrigation was cut off at 12°Be1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Pre-dawn water stress in grapevines irrigated at 20% PAW depletion until harvest was less than in those where irrigation was cut off at 12°B”
Claim · model-written summary
Stomatal control apparently limited leaf water potential differences between treatments, with partial stomatal closure.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Pre-dawn water stress in grapevines irrigated at 20% PAW depletion until harvest was less than in those where irrigation was cut off at 12°B”
e2“Sap flow measurements indicated that partial stomatal closure seemed to have occurred over the warmest part of the day”
e3“Apparently, stomatal control limited Ψl differences between treatments although extensive soil water depletion occurred where irrigation was cut off during ripening”
Claim · model-written summary
The level of PAW depletion did not affect accumulated leaf water potential where irrigation was continued during ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“If accumulated leaf water potential (ΨT) is considered, irrigation cut off at 12°B and 15°B induced more water stress in grapevines from 04:00 to 24:00 compared to those vines where irrigation was continued until harvest”
e5“Where irrigation was continued throughout the ripening period, the level of PAW depletion did not affect ΨT”
Claim · model-written summary
During the sunshine period, ΨT was higher at 40% PAW depletion, and with irrigation cut off, than with irrigation at 20% depletion until harvest.
- Treatment
- 40% PAW depletione6
- Outcome
- ΨTe6
- Direction
- highere6
- Qualifier
- during the sunshine period (08:00 until 18:00)e6
- Comparator
- irrigated at 20% depletion until harveste6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“However, during the sunshine period (08:00 until 18:00), ΨT in grapevines subjected to 40% PAW depletion, as well as those where irrigation was cut off, was higher than in the ones that were irrigated at 20% depletion until harvest”
Claim · model-written summary
Where irrigation was cut off at 12°B, water potential did not recover during the first half of the night to the level of the other treatments.
- Treatment
- irrigation was cut off at 12°Be7
- Outcome
- water potentiale7
- Direction
- unable to recovere7
- Qualifier
- During the first half of the nighte7
- Comparator
- the other treatmentse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“During the first half of the night, i.e. from 18:00 until 24:00, water potential in grapevines where irrigation was cut off at 12°B was unable to recover to the same level as in those exposed to the other treatments”
Claim · model-written summary
Extensive soil water depletion occurred where irrigation was cut off during ripening.
- Outcome
- extensive soil water depletione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Pre-dawn water stress in grapevines irrigated at 20% PAW depletion until harvest was less than in those where irrigation was cut off at 12°B”
e3“Apparently, stomatal control limited Ψl differences between treatments although extensive soil water depletion occurred where irrigation was cut off during ripening”
The same questions in other papers
irrigation · physiology: water · VitisPositive and negative results
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See all 47 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.