In a context of scarcity of water resources, a way of adapting to climate change can be through the reduction of planting density. This is especially true for non-irrigated vineyards. Observation and modelling of the water balance in a vine plot shows that non-irrigated low density vineyards (2,500 vines/ha) are significantly less sensitive to drought compared to medium (3,333 vines/ha) or high (5,000 vines/ha) density vineyards. An adaptation measure may therefore be to increase inter-row space when planting new plots.

Note that the difference is less noticeable (but still existing) in soils with low water reserves. The reduction in planting density, however, has an impact on production, with an expected reduction in yields. However, the economic impact according to a study conducted in Bordeaux and Avignon is positive: the gross margin per hectare increases thanks to the reduction in production costs, especially in the case of low-value vineyards (in €/kg).

Increasing inter-row space is therefore potentially a good way to continue growing vines on very dry land without irrigation. Compared to gobelet pruning, another adaptation practice, this measure has the advantage of remaining adapted to existing mechanisation tools.

This technique is, however, too little documented by winegrowers and technical and scientific bodies to date, although it is regularly mentioned. Recall also that in the context of a production in name, the minimum density is fixed by the specifications. This regulation limits the development of such innovation.

Authors : Marc Nougier (SupAgro), Audrey Naulleau (INRAE)

References:

• Reduced density is an environmental friendly and cost effective solution to increase resilience to drought in vineyards in a context of climate change, Van Leeuwen et al., 2019