Influence of rootstock, irrigation level and recycled water on water relations and leaf gas exchange of Soultanina grapevines

Abstract

The effects of rootstock variety (41B, 1103P and 110R), irrigation level (0.50, 0.75 and 1.00 of the evapotranspiration) and water quality (recycled versus freshwater) on water relations and gas exchange of potted Soultanina grapevines were investigated during two growing seasons. An early reduction of predawn leaf water potential ( Ψ pd) was detected for vines irrigated with recycled water in both the seasons. However, assimilation rate ( A) and stomatal conductance ( g s) were reduced only late in the first year at higher irrigation levels. This was consistent with the higher reduction of Ψ pd at these treatments indicating that the development of a water deficit due to salt accumulation reduced gas exchange. At midday during 1998, leaves on vines grafted on 1103P and 110R had lower leaf water potentials and higher g s and A. An opposite effect was however observed early in June the following season, although later in that season no differences were detected among rootstocks. That differentiation of rootstock effect between seasons may have been induced by alterations in source/sink relations due to differences in yield among rootstocks and its effects on leaf area. Irrigation level strongly affected water relations and gas exchange. Both A and g s were significantly correlated with soil moisture. A differentiation in these relations was observed among rootstocks late in 1998 which probably resulted from the change in leaf area development among rootstocks during that period.