Resumen de Phosphorus speciation of dormant grapevine (Vitis vinifera L.) canes in the Barossa Valley, South Australia
A. L. Doolette, Ronald J. Smernik
Background and Aims The phosphorus (P) contained in annual prunings can represent a substantial proportion of annual vineyard P addition. Availability of P to the growing vines is controlled by the forms of P present. Solution 31P nuclear magnetic resonance spectroscopy was used to investigate the chemical composition of P in dormant canes taken from two cultivars of Vitis vinifera L., Shiraz and Viognier, collected from nine vineyards.
Methods and Results The main forms of P detected were similar, although the proportion of these varied; orthophosphate comprised 37–57% of total P, phospholipids 8-15%, myo-inositol hexakisphosphate (phytate) 20–34% and a specific isomer of myo-inositol pentakisphosphate (rarely identified previously in plant material) 9–25%; DNA and pyrophosphate contributed <1% of total P. Variation in P composition appeared unrelated to grape cultivar, but varied with vine P status. Higher total P concentration correlated with proportionately more orthophosphate and phytate.
Conclusions Grapevine prunings represent a nearly equal combination of immediately available and potentially recalcitrant forms of P.
Significance of the Study This study is one of the first to examine the P composition of dormant grapevine canes, which is a prerequisite to predicting the contribution they make to P nutrition.
