Grapevine shoot growth and stomatal conductance are reduced when part of the root system is dried

Split-root plants, where the root system was divided between two containers, were used to study the effect of partial drying of the root system on shoot growth and stomatal conductance of grape cultivars Chardonnay and Shiraz (syn. Syrah). When part of the root system was allowed to dry while the other part was well-watered, shoot growth was significantly reduced. Changes in both shoot growth and stomatal conductance in response to half-drying took place in the absence of any change in shoot water status suggesting the involvement of a non-hydraulic signal in mediating this response. Recovery of both shoot growth rate and stomatal conductance appeared to start before rewatering of the dried half of the root system, and coincided with the time when there was no further decrease of soil water content in the dried container. This appears to be first report of a significant decrease in shoot growth in response to partial drying of the root system of grapevines.