Drought resilience of long term dry-farmed grapevines ('Vitis vinifera' L.)

We explored the long-term drought resilience of field-grown unirrigated (or dry-grown) grapevines of pre-clonal origin from shallow (SR) and deep (DR) soils representing low and high soil water availability, respectively, in a warm, Mediterranean climate. Despite lower soil moisture available to SR vines, both deep and shallow-rooted vines had similar vine water status, based on measurements of midday stem water potential ({Psi}s), and leaf net photosynthesis (An). Due to the lower stomatal conductance (gs), SR had higher intrinsic water use efficiency (WUEi) than DR, however the carbon isotope ratio ({delta}13C) of the fruit at harvest was similar between the two groups. Our observations suggest a degree of drought adaptation in the SR vines resulting from multi-decadal cyclical droughts. Overall, we demonstrate that pre-clonal Cabernet Sauvignon grapevines dry-grown in shallow soils have an enhanced resilience to drought compared to dry-grown vines in deep soils. This study has implications for selection of crop genetic material in a changing climate.