From July Heat to Wine Quality: The Role of Water Stress
The vine is an extraordinarily adaptable plant, capable of withstanding periods of drought like the one we experienced from late May to early July.
What is the secret of this resilience?
- A deep root system that can reach water in the lower soil layers.
- The ability to adjust its metabolism according to water availability.
Photosynthesis, in fact, is a process that requires water: by using atmospheric carbon dioxide (CO₂) and water, and thanks to light, the plant produces sugars and oxygen (O₂).
What happens in the vineyard when drought begins?
When water becomes scarce, the vine can partially close its stomata – small pores located on the underside of the leaves that allow gas exchange – thus reducing photosynthesis and water loss. This metabolic slowdown results in slower growth.
A moderate water stress can actually have positive effects on grape quality, encouraging the synthesis and concentration of compounds such as acids, aromas, and flavonoids, also because the berries remain smaller. However, if drought is prolonged and accompanied by intense heatwaves, the effects become harmful both for that year’s production and for the plant itself.
Severe water stress can cause:
- A reduction in grape quantity.
- A halt in ripening.
- Shriveling of the fruit.
- Yellowing of the leaf surface.
- Increased pH in the must.
Fortunately, the soils surrounding Podere Il Casale are rich in clay, which is an advantage because clay has a high water retention capacity. The reserves accumulated during the rainy spring in the deeper layers help to limit the effects of drought.
To further improve water availability, we work on the soil’s microbial life, which helps to:
- Improve soil structure.
- Increase its ability to retain moisture.
- Encourage greater root development.
If these reserves are not sufficient, what other strategies can be adopted?
- Temporarily reduce the leaf surface by topping the shoots: a larger canopy increases transpiration. Water consumption varies according to several factors, including solar radiation, wind, humidity, training system, and vineyard exposure.
- Manage the soil and the grass cover between rows to reduce water loss by evaporation.
- Emergency irrigation, as a last resort, to safeguard production and plant health.
Careful vineyard management during climate stress is essential to ensure the quality of our wines and the sustainability of the biodynamic and organic farming we practice at Podere Il Casale.
