Four research centres in Extremadura, Castilla León, Castilla La Mancha and Galicia have launched a project with the main objective of mitigating the effects of climate change. It studies winter and summer irrigation and other more sustainable agronomic practices in red grape varieties such as Garnacha, Tempranillo, Syrah and Mencía.

The project is called "Annual water and agronomic management in red grape varieties to improve their productive and qualitative management and reduce the effects of climate change" and is funded by the State Plan for Scientific and Technical Research and Innovation.

In addition to the priority of efficient water use in the current situation, climate change is causing alterations in terms of pests and diseases, vine phenology, ripening process, grape yield and quality. The ripening period is being brought forward to the summer months, coinciding with higher temperatures, which has an adverse effect on quality, related to compounds that influence the composition, colour and aromas of wines, such as sugars, organic acids and phenolic compounds.

In view of this situation, it is necessary to generate knowledge to propose sustainable cultivation systems in viticulture, but also more efficient in terms of yield, quality and use of resources.

This project with red grape varieties comprises two main actions related to irrigation and crop management with different agronomic practices, to contribute, as a whole, to maximise the water used by the plant, improve the microclimate of the vine and in the cluster area, regulate production, increase grape quality and reduce the use of herbicides.

Irrigation and agronomic practices
The irrigation study includes novel aspects: different irrigation frequencies and periods in the annual cycle of the crop and the response of the crop to winter irrigation to estimate the most appropriate moment in the event of low rainfall or irregular rainfall in that season of the year. Furthermore, the trials will study the management of the canopy or aerial part of the plant, leaf density and leaf distribution, and their effects on photosynthetic activity, solar radiation reaching the bunches, their impact on ripening and berry composition.

This national project brings together four research groups specialised in viticulture, but with different backgrounds, so some of the actions will be complementary, providing added value to the project. In addition to the common tasks, each team will deepen the project in a specific aspect. It is coordinated by the Centre for Scientific and Technological Research of Extremadura (CICYTEX), with the participation of the Agrarian Technological Institute of Castilla León (ITACYL); the Provincial Technical Agronomic Institute of Albacete (ITAP); and the University of Santiago de Compostela (USC).

Extremadura and Castilla León will deal more specifically with monitoring and data collection for the adjustment of the vine canopy to achieve the most optimal conditions.

In Castilla La Mancha, the vines will be covered in the pre-brotation phase with a roof or shed to simulate a period of winter drought and to study techniques that can mitigate the negative effects.

The alternative to herbicides: slate mulching
In Galicia, an inorganic mulch will be used on the soil, using waste or waste material from the slate industry in the area, to assess its effectiveness in reducing weeds in the vineyard row, as an alternative to chemical herbicides. It will also be examined whether this novel technique is useful in irrigation efficiency to better conserve rainwater, helps to improve the soil profile or provides other advantages. Studies on gravel or inorganic mulching are limited and trials are needed to understand the actual effects on vineyards.

The project focuses on four red grape varieties adapted to each area. In Extremadura, in the experimental plot of CICYTEX, a trial will be carried out with the Garnacha variety, in Castilla León the studies will be done with the Tempranillo variety in Ribera del Duero, in Castilla La Mancha they will be done with Syrah in Albacete, and in Galicia with Mencía in Ribeira Sacra.

All the groups will evaluate, at harvest time, the effect of the irrigation treatments and agronomic practices applied on the yield, productivity and quality of the grapes.

Overall, the project has four main structured tasks: influence of irrigation frequency and water use efficiency; influence of winter water availability regulation on yield and plant behaviour throughout the growing cycle; influence of canopy top opening on microclimate, water relations, and yield and vegetative balance; influence of the use of inorganic mulch on weed control and irrigation efficiency.

The project is funded by the State Plan for Scientific and Technical Research and Innovation.