Abstract
A field trial during the 2009 and 2010 seasons evaluated the impact of winter rainfall on the main compounds responsible for green aromas in grapes and wines, 3-isobutyl-2-methoxypyrazine (IBMP) and C6 compounds. These compounds are considered undesirable in grapes and wines above the threshold concentration. Methods and Results: One treatment subjected vines to average rainfall, while the other excluded winter rainfall by covering the ground with a plastic tarpaulin during the entire dormant season (November to mid-March). Irrigation for both treatments was maintained at a weekly rate of 70% of crop evapotranspiration until commercial harvest. Canopy growth, berry size and vine yield were significantly reduced by rainfall exclusion, and a significant increase in the fruit to pruning mass ratio was recorded from one season to another. Synthesis of IBMP was significantly greater in vines under normal rainfall, whereas C6 compounds were significantly different between treatments only at the end of the second season. Fruit and wine composition, mainly colour and mouthfeel compounds, were positively affected by the absence of rainfall in both years. Wine descriptive analysis showed that the lack of rainfall produced wines perceived as less green and of more intense fruit attributes in the first season. As a consequence of the reduction in vine growth, however, the same treatment produced wines less intense in fruit aromas and of inferior tannin quality in the following season. Conclusions: These results show that the soil moisture level prior to budbreak affects both canopy growth and vine yield, even when irrigation is applied following budbreak. If the rainfall level is below normal, the positive effect on fruit and wine composition achieved through smaller berry size may be offset by a significant reduction in canopy growth, resulting in severely unbalanced vines, i.e. inadequate fruit to pruning mass ratio. Significance of the Study: Growers aiming to minimise the level of IBMP at harvest would benefit from applying moderate deficit irrigation and nitrogen fertilisation rates and also might achieve an earlier harvest date for those vineyards where the absence of undesirable vegetal characters is considered a key harvest metric.
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Claims 10
Claim · model-written summary
Excluding winter rainfall significantly reduced canopy growth, berry size and vine yield of Merlot vines compared with average rainfall.
- Taxon
- Vitis vinifera L.
Vitis viniferat0 - Material
- Merlott0
- Treatment
- rainfall exclusione0
- Outcome
- Canopy growth, berry size and vine yielde0
- Direction
- reducede0
- Comparator
- average rainfalle1
- Setting
- Californiat0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e0“Canopy growth, berry size and vine yield were significantly reduced by rainfall exclusion”
Claim · model-written summary
The fruit to pruning mass ratio of the vines increased significantly from one season to the next.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Outcome
- fruit to pruning mass ratioe0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e0“a significant increase in the fruit to pruning mass ratio was recorded from one season to another”
Claim · model-written summary
Synthesis of IBMP was significantly greater under normal rainfall than under winter rainfall exclusion.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- excluded winter rainfalle1
- Outcome
- Synthesis of IBMPe3
- Direction
- decreaseinferrede3
- Comparator
- normal rainfalle3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e3“Synthesis of IBMP was significantly greater in vines under normal rainfall”
Claim · model-written summary
C6 compounds differed significantly between rainfall exclusion and average rainfall only at the end of the second season.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- excluded winter rainfalle1
- Outcome
- C6 compoundse3
- Qualifier
- only at the end of the second seasone3
- Comparator
- average rainfalle1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e3“C6 compounds were significantly different between treatments only at the end of the second season”
Claim · model-written summary
Fruit and wine composition, mainly colour and mouthfeel compounds, was positively affected by the absence of winter rainfall in both years.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- absence of rainfalle0
- Outcome
- Fruit and wine compositione0
- Direction
- positively affectede0
- Qualifier
- in both yearse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e0“Fruit and wine composition, mainly colour and mouthfeel compounds, were positively affected by the absence of rainfall in both years”
Claim · model-written summary
In the first season, lack of rainfall produced wines perceived as less green.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- lack of rainfalle6
- Outcome
- perceived as less greene6
- Direction
- lesse6
- Qualifier
- in the first seasone6
- Comparator
- average rainfalle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e6“the lack of rainfall produced wines perceived as less green and of more intense fruit attributes in the first season”
Claim · model-written summary
In the first season, lack of rainfall produced wines with more intense fruit attributes.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- lack of rainfalle6
- Outcome
- fruit attributese6
- Direction
- more intensee6
- Qualifier
- in the first seasone6
- Comparator
- average rainfalle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e6“the lack of rainfall produced wines perceived as less green and of more intense fruit attributes in the first season”
Claim · model-written summary
In the following season, winter rainfall exclusion produced wines less intense in fruit aromas.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- excluded winter rainfalle1
- Outcome
- fruit aromase2
- Direction
- less intensee2
- Qualifier
- in the following seasone2
- Comparator
- average rainfalle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e2“the same treatment produced wines less intense in fruit aromas and of inferior tannin quality in the following season”
Claim · model-written summary
In the following season, winter rainfall exclusion produced wines of inferior tannin quality.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Treatment
- excluded winter rainfalle1
- Outcome
- tannin qualitye2
- Direction
- inferiore2
- Qualifier
- in the following seasone2
- Comparator
- average rainfalle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e1“One treatment subjected vines to average rainfall, while the other excluded winter rainfall”
e2“the same treatment produced wines less intense in fruit aromas and of inferior tannin quality in the following season”
Claim · model-written summary
Growers aiming to minimise IBMP at harvest are advised to apply moderate deficit irrigation and moderate nitrogen fertilisation.
- Taxon
- Vitis vinifera L.Vitis viniferat0
- Outcome
- moderate deficit irrigation and nitrogen fertilisation ratese2
- Qualifier
- minimise the level of IBMP at harveste2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Vitis vinifera L. cv. Merlot in California”
e2“Growers aiming to minimise the level of IBMP at harvest would benefit from applying moderate deficit irrigation and nitrogen fertilisation rates”
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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.