The fast-slow root economics spectrum in wine grapes: resource acquisition strategies in a common perennial crop

The Leaf Economics Spectrum (LES) is a widely described pattern in plant ecology, representing plant resource-use strategies described by variability in resource conservative to resource acquisitive leaf functional traits. Root traits are also hypothesized to vary along a Root Economics Spectrum (RES) defining belowground resource acquisition strategies. While observed in wild plants, it is unclear if the RES defines belowground strategies in crops, and if a potential RES covaries with a LES in crops. Using 12 cultivars of grapevine scions, spread acorss three unique rootstocks, we measured five RES traits— specific root length (SRL), root tissue density (RTD), root diameter (D), root nitrogen and carbon concentrations—and three LES traits—leaf mass per area, leaf N concentrations, light-saturated photosynthetic capacity on a per leaf mass basis. We tested for 1) the existence of an intraspecific RES in grapevine, and 2) covariation between an LES and RES. Root traits varied along a conservative-acquisitive RES, defined by positive covariation between RTD and D, which both traded off against SRL. Scion identity explained ~49.2% of belowground trait variation. We also found evidence for orthogonality between the RES and LES, suggesting that above- and belowground strategies vary independently of one another in grapevine.