Leaf and stem hydraulic traits in relation to growth, water use and fruit yield in Prunus avium L. cultivars

Physio-anatomical traits of rootstock have been considered as determinants of vigor in grafted plants. We evaluated how hydraulic traits of three Prunus avium cultivars grown on the same rootstock are related to tree growth and patterns of biomass allocation between vegetative and reproductive parts as well as total water consumption to determine how water, as a limiting resource for agriculture, might be optimized by choosing appropriate cultivars that are at the same time the most successful from the point of view of fruit production. Bing, Lapins and Van cultivars growing under field- and well-irrigated conditions were selected. Leaf and stem hydraulic conductance (K (Leaf) and k (S)), leaf vulnerability to cavitation, water relations traits, water use and assimilation and growth rates as well as fruit yield were measured. The cultivar with high leaf vulnerability to cavitation and low k (S) and sap flow (Lapins) had low vegetative growth, but larger fruit production compared to the cultivars with higher k (S), resistance to cavitation and water use (Bing and Van). As leaf water potential and k (S) were lower and leaves appeared to be embolized in the cultivar that had lower carbon allocation to vegetative organs during the reproductive period (Lapins), we hypothesize that water instead of moving into the leaves is delivered to the fruits, representing the main sink for water transport. It is possible that increases in the dysfunction of the hydraulic system in the most vulnerable cultivars to cavitation during the reproduction stage (Lapins) may represent a signal for enhancing the delivery of water to fruits. This information related to optimization of crop water use in relation to yield can be useful for selecting cultivars with high yield and low water use. This study also shows that physiological traits of the scions substantially affect growth patterns, fruit production and water relation of the plants.