Potatoes | Management of water deficit in potato cultivation: playing the varietal card

The choice of variety is the first factor which allows adaptability of its system according to its production capacities and the desired destinations.

The objective of this trial is to characterize the tolerance of each variety to water stress and thus be able to refine the agronomic recommendations to be made to producers and manufacturers.

Effect of irrigation: une baisse généralisée mais différenciée

Analysis of the results highlights an almost systematic reduction in yield in non-irrigated conditions. This observation confirms the major impact of water deficit on potato cultivation, particularly in the tuberization and enlargement phase.

However, beyond this overall trend, the amplitude of the decline varies significantly depending on the genotypes (varieties). This interaction between genotype and water regime reflects a diversity of physiological responses on the part of varieties to stress: water efficiency, maintenance of photosynthetic activity, limitation of tuber abortion, etc.

Typology of varietal behaviors

The analysis makes it possible to distinguish three main profiles:

1. Varieties tolerant to water stress

(DB-649-16-3, Palace, Theda, Storm, Lady Avalon et Travis)

These varieties present either a high level of yield in non-irrigated conditions, or a limited irrigated/dry differential. They combine stability and relative performance, suggesting good water use efficiency. Their positioning above or close to the average in dry conditions makes them references for constrained irrigation systems.

2. Varieties sensitive to water stress

(Honorata, Gravity, Valencia, Norman and Leonore)

These varieties record low dry yields (around 5.5 to 7.5 t DM/ha), reflecting a strong dependence on irrigation. Their drop in performance indicates a marked sensitivity to water deficits, possibly linked to a lesser capacity for stomatal regulation or to a less exploratory root system.

3. Varieties with high potential but unstable

(Esperanto, Lady Jane et Carlos)

These profiles are characterized by high yields in irrigated conditions but strong degradation in dry conditions. Their genetic potential is real, but strongly conditioned by the availability of water, which makes them primarily intended for irrigated contexts.

Focus on the material dry: a criterion discriminant

Beyond the overall yield, the capacity to produce dry matter constitutes a determining lever for the transformation sectors. In this regard, certain varieties clearly stand out, notably DB-649-16-3 and Lady Avalon, which combine good MS levels and stress tolerance.

Notable fact: Norman also displays a good ability to produce dry matter, despite its sensitivity to water deficit. This underlines the importance of crossing the criteria (yield, stability, quality) in the variety choice.

Teachings agronomic and recommendations

This essay highlights several key points:

• Water stress systematically impacts yield, but with an intensity depending on the genotype.

• The varietal variability is sufficiently marked to constitute a lever for agronomic adaptation.

• The choice of variety must be considered according to irrigation capacity and production objectives (yield vs. dry matter).

• In limiting water conditions: favor DB-649-16-3, Palace, Theda, Storm, Lady Avalon.

• In irrigated systems: possibility of promoting varieties with high potential such as Esperanto, Lady Jane or Carlos.

• For industrial outlets: integrate the dry matter criterion into varietal arbitration.

Conclusion

In a context of climate change, this trial confirms the strategic interest of varietal selection as a lever for adaptation. The identification of tolerant and stable profiles constitutes a major asset for securing production, particularly in areas where access to irrigation becomes limiting.

However, it is important to take into account the destination of the tubers produced before choosing the variety. These varieties have different responses to processing. Yield is not the only parameter to take into account.