Budburst Flashcards
Why is Budburst important?
It helps vineyard managers to predict key dates like flowering and harvest. And the timing of budburst can determine the yield for the next harvest and the health of a vine. How quickly spring temperature increase can have an affect on the homogeniety of later stages in the vine cycle.
Define Budburst
When buds swell and open, and growth resumes after winter dormancy.
What are the four factors that determine when budburst occurs?
Air Temperature
Grape variety
Hormones
Pruning system
What temperatures are needed for a compound bud to burst?
Average air and soil temps >10 deg C for 7-10 consecutive days
What are 2 physiological mechanisms that affect Budburst.
Hormones, and Plant reserves
Explain how hormones affect budburst
- Abscisic acid maintains dormancy and inhibits budburst so must be eliminated.
- Cytokinins are produced in the roots and stimulate cell division and therefore budburst.
Name 2 hormones that affect budburst.
- Abscisic acid
- Cytokinins
How do a plants carbohydrate reserves affect budburst?
They support new growth after budburst. Low levels of carbohydrate reserves will delay budburst
What is are environmental factor that affects budburst?
Both these mechanisms are affected by inhibitory signals that are dependent on:
Temperature - Average daily temperature must be above 10 degrees and each cultivar has different temps when inhibitory signals are activated.
Root temperature - High root temps lead to an earlier budburst and different soils warm roots up faster than others.
Disease will affect carbohydrate reserves.
What is a cultural factor that affects budburst?
Pruning - If winter pruning is done too late it may delay budburst. Pruning will also determine the amount and position of buds.
Why do varietal selections affect budburst?
Varieties can be released from dormancy at different temperatures depending on their variety: Early budding e.g. pinot noir or late budding.
