[eng] Genetic improvement of crop Water Use Efficiency (WUE) is a general scope
because the water scarcity. For grapevines, this results are relevant and need an urgent
response because their wide distribution in semi-arid areas. New cultivars are difficult to
introduce in viticulture due to the narrow dependency of consumer appreciation often linked
to a certain particular wine taste. Clones of reputed cultivars would presumably be more
accepted but little is known on the intra-cultivar genetic variability of the WUE. The present
work compares, on the basis of two field assays, the variability of intrinsic water use
efficiency (WUEi) in a large collection of cultivars in contrast with a collection of clones of
Tempranillo cultivar. The results show that clonal variability of WUEi was around 80% of
the inter-cultivar, thus providing a first assessment on the opportunity for clonal selection by
WUE. Plotting the WUEi data against stem water potential or stomatal conductance it was
possible to identify cultivars and clones out of the confidence intervals with significantly
higher and lower of WUEi values. Similarly, the comparison of the coefficient of the variance
showed for intra-cultivars values of WUEi around 80% of the clonal ones. The present results
contribute to open the expectative for a genetic improvement of grapevine WUE