LAUSR

Abstract The purpose of this study was to investigate the mechanisms underlying the effect of rootstocks on table grapevines grown under irrigated conditions in the arid North macro-zone of Chile. Grapevine cv. Red Globe grafted onto three rootstocks (Harmony, Saint George and Salt Creek) were studied Structural and physiological parameters were monitored at different phenological stages under optimal production conditions. An outstanding yield increment brought about by the rootstocks Harmony and Salt Creek was correlated with increased individual leaf and specific leaf area, pruning weight (proxy for total leaf area), photosynthesis per unit leaf mass, sugar in leaves and root carbon reserves. In addition, these high yielding rootstocks induced higher contents of light-harvesting chlorophyll a/b protein of photosystem II and total chlorophyll in the leaves of the scion. No correlations of yield with traits involved in water use (relative water content or instantaneous water use efficiency) were observed. The effects of rootstocks on the light capture capacity of the scion directly affected carbon assimilation and storage and, accordingly, yield. Therefore, the identified traits are valuable targets for screening and selecting yield efficient rootstocks for irrigated table grape production in arid zones.