Interactive effect of irrigation level and methodology/strategy on physiological and biochemical responses in two grape varieties differing in drought adaptation

摘要

The effects of deficit irrigation (DI) and partial rootzone drying (PRD) on physiological and biochemical parameters were examined in two grapevine varieties (cvs. Mavrodafni and Savatiano).rnGrapevines had a split root system and were subjected to one of the following five irrigation treatments: control in which both parts of the rootzone were kept to soil medium capacity; deficit irrigation (DI_(75), DI_(50)) receiving 75% and 50% irrigation water of control plants, respectively to both sides of the rootzone; (PRD_(75), PRD_(50)) receiving 75% and 50% irrigation water of control plants successively to one and the other part of the rootzone.rnResults indicated that the reduction of irrigation water resulted in lower predawn leaf water potential (Ψ_(PD)) and stomatal conductance (g_s) in Mavrodafni compared to Savatiano. Furthermore, the differences in Ψ_(PD) between DI and PRD treatments in Mavrodafni were significantly higher compared to Savatiano. Furthermore, Mavrodafni PRD_(50) plants exhibited significant higher g_s values compared to the DI_(50). Leaf [abscisic acid] was significantly higher in PRD compared to DI at the onset of the water stress period in Mavrodafni. In contrast, [cytokonins] followed an opposite trend. Mavrodafni exhibited significantly higher xylem sap pH at a given level of Ψ_(PD) compared to Savatiano, whilst no significant differences were measured between the two irrigation treatments (DI_(50) & PRD_(50)) in both varieties.rnOverall, results suggest that DI could be more effectively used in those genotypes which are considered more adapted to drought, while in vulnerable varieties the reduction in irrigation water would suggest the implementation of PRD as a preferred irrigation strategy.