Differential accumulation of potassium in the vegetative and reproductive organs of three grapevine cultivars

Vine nutrition and vineyard fertilizer management have long-term implications for plant performance, notably vigour, crop load and fruit composition. Grape and wine composition is intrinsically linked to vineyard management practises. Wine sensory outcomes such as flavour, colour and aroma are heavily dependent upon intrinsic grape properties including pH, which in turn is influenced by berry potassium (K) concentration. Cultivar differences in the accumulation of nutrients is evident, however, tracking the accumulation of K in the various vine tissues is crucial for understanding how this macronutrient should be monitored during the season to achieve optimum growth performance and grape quality. We studied three economically important wine grape cultivars in Australia, grown under identical conditions, to determine how K accumulation differs between the cultivars, between the vegetative and reproductive organs and between two node positions on the shoot. The samples were collected at flowering and veraison and analysed for K by inductively coupled plasma atomic emission spectroscopy (ICP-AES). K concentrations ([K]) increased or decreased between these two phenological stages depending on cultivar, organ and node position. [K] in the berry and flower were not correlated with [K] in the leaf blade, petiole, or bunch stem. The differential accumulation of K in various organs points towards complex partitioning and mobilisation patterns, and this will have implications for berry pH and acidity at harvest. The differential accumulation of K between cultivars suggests that cultivar specific reference standards are required.