Abstract

Sweet cherry is mainly cultivated in arid and semi-arid areas. In the last decade, these areas have experienced a dramatic reduction in rainfall, which has resulted in water shortage for sweet cherry. The use of specific root-stock and scion combinations could help improve the tolerance of plants to water shortage events. This study reports on the influence of rootstocks on whole-plant performance under water deficit as detected by hydraulic sensitivity, root hydraulic conductivity (Lp), water use efficiency and sugar content. Four Prunus rootstocks/scion combinations -'Bing/Colt', 'Lapins/Colt', 'Bing/Mx60', 'Lapins/Mx60', and two self-rooted rootstocks Colt and Maxma 60 -were acclimated for 30 days and then exposed to well-watered (WW) and water deficit (WD) conditions for 36 days. Whole-plant transpiration and growth were both influenced by WD, and two groups were identified based on responses: 'Bing/Colt', 'Bing/Mx60' and 'Mx60' had an early reduction (conservative strategy), whereas 'Lapins/Mx60', 'Lapins/Colt' and 'Colt' had late reduction (productive strategy) in transpi-ration as WD increased. Among the combinations, 'Lapins/Colt' and 'Colt' showed a remarkable growth response to the WD being less affected in shoot and root biomass. The 'Colt' rootstock maintained a higher psi gs50 (near-isohydric behavior) than combinations using the 'Mx60' rootstock (near anisohydric behavior). The relationship between Lp and the variation of psi pre-dawn-psi midday showed differences among rootstock/scion combinations, and under WD condition the reduction in Lp induced by WD affected the whole-plant WUE of combinations differ-ently. Sucrose and sorbitol content in leaves and roots of WD-tolerant combinations such as 'Colt' and 'Lapins/ Colt', showed a remarkable increase under WD condition. Our finding highlights the importance of the specific interaction between rootstock and scion, suggesting that combinations characterized by a higher water uptake capacity under conditions of lower water availability would be sustainable under minimal to moderate water deficit.