- Maturity
- Sunlight exposure
- Temperature
- Water Status
- Vine vigor
- Yield
The primary aim of the sunlight exclusion experiment was to determine:
(1) if the treatments caused changes in IBMP concentrations
(2) if these changes were due to the alteration of either VvOMT3 expression or IBHP concentration. The authors found that light reduced the expression of VvOMT3 and the concentration of IBHP, suggesting that a combination of these factors reduces IBMP concentration when fruit has greater light exposure. Berry shading has a greater influence on IBMP concentrations in preveraison berries, when methoxypyrazines accumulate.
Cabernet Sauvignon vines with low crop level produced grapes with higher IBMP concentrations than vines with high crop level, however, the effect of crop level manipulation on IBMP concentration was not as great as the effect observed by the elimination of light exposure on bunches.
In order to minimize the impact of IBMP accumulation in Carbernet sauvignon, the authors suggest that canopy management regimes that result in exposed bunches very early in fruit development should be implemented. Altering canopy management after veraison will have less of an effect on IBMP concentrations.
References:
1. Jake D. Dunlevy, Kathleen L. Soole, Michael V. Perkins, Emily L. Nicholson, Suzanne M. Maffei and Paul K. Boss, Determining the Methoxypyrazine Biosynthesis Variables Affected by Light Exposure and Crop Level in Cabernet Sauvignon, Am. J. Enol. Vitic., December 2013, vol. 64 no. 4 450-458.
2. The structure of IBMP was found here: Chemical Book 3-Isobutyl-2-methoxypyrazine(24683-00-9)
3. All structures were drawn by the freely available drawing program from ACD Labs called ACD/ChemSketch Freeware.
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