A study reveals that the rootstock-variety combination is key to increasing drought tolerance in cherry trees

A study by CEAF shows that the interaction between root system and variety determines how trees cope with water stress, opening up new strategies for fruit growing under extreme drought conditions.

A study conducted by the director of the Center for Advanced Studies in Fruit Growing (CEAF), Dr. Guillermo Toro, together with researchers Paula Pimentel and Ariel Salvatierra, demonstrated that the combination of rootstock and scion can modulate drought tolerance in sweet cherry trees.

The research was published in the scientific article "Trade-off between hydraulic sensitivity, root hydraulic conductivity, and water-use efficiency in grafted Prunus under water deficit conditions", which analyzes how different combinations influence water-use efficiency and tree survival under water stress.

Climatic context

Chile, the main fruit exporter in the Southern Hemisphere, is currently experiencing a reduction in rainfall ranging from 55% to 75% in its central region. In this context of severe drought, CEAF researchers have shown that the interaction between scion and rootstock is crucial for the plant’s hydraulic response.

Dr. Guillermo Toro explains that "given the uncertainty in water availability, it is no longer sufficient to choose based on vigor or variety. It is essential to select specific rootstock–variety combinations that maintain water-use efficiency under water stress conditions."

Methodology: progressive stress and precise measurement

To evaluate these responses, the team subjected different Prunus combinations to a progressive substrate drying process over 36 days, until reaching the permanent wilting point.

Measurements were carried out using the Fraction of Transpirable Soil Water (FTSW), through daily pot weighing (gravimetric method) to identify the exact moment when transpiration begins to decline.

The study also integrated two high-precision techniques:

• Root hydraulic conductivity: using a High-Pressure Flow Meter (HPFM), the capacity of roots to transport water was assessed. Results indicate that the rootstock regulates stomatal opening through hydraulic resistance, limiting flow before vascular failure occurs.

• Biochemical sugar analysis: using High-Performance Liquid Chromatography (HPLC), it was found that the most tolerant combinations increase sorbitol content in leaves and roots. This compound acts as an osmoprotectant, allowing the plant to retain water and maintain its functions under stress conditions.

Two strategies to cope with drought

1. Conservative strategy: observed in combinations such as 'Bing/Colt', where the plant reduces transpiration early to conserve water, which limits growth.
2. Productive strategy: found in combinations such as 'Lapins/Colt', which maintain transpiration and growth longer thanks to greater water uptake and osmotic adjustments.

According to Toro, this knowledge changes the way we understand irrigation: it is not only about how much water is in the soil, but also how each plant absorbs, transports, and regulates it."

From this perspective, he warns that not all combinations should be treated in the same way, as each presents different response thresholds to water stress, reinforcing the need for more precise agriculture, where irrigation is adapted to crop physiology.

The study concludes that the success of cherry orchards under climate change scenarios depends not only on the variety, but also on the strategic selection of the rootstock, capable of optimizing water-use efficiency through proper hydraulic connection between root and stem.

The future of orchards must be based on physiology and adaptation, not only on tradition or commercial availability," the researcher concludes.

Source: Ecociencias Journal

Image source: Stefano Lugli

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