PARTITIONING OF DRY-WEIGHT, NITROGEN, AND POTASSIUM IN CABERNET-SAUVIGNON GRAPEVINES FROM ANTHESIS UNTIL HARVEST

Entire Cabernet Sauvignon grapevines grafted onto 5C rootstock were harvested on four separate dates during the growing season, beginning at anthesis. Dry weights, nitrogen, and potassium subsequently were determined on all vine organs at each harvest date. Dry weights of roots increased throughout the season, while that of the trunk varied from date to date. The dry weights of the fruiting canes, leaves, stems (main axis of the shoot) and clusters increased on each harvest date. Potassium concentrations in the root system remained almost constant during fruit development with little K redistribution to the other organs. The concentrations of K in the leaves, stems, and clusters decreased from anthesis until 1 August. However, the decreases in K concentrations of those three organs were due to a dilution effect as K content in each organ increased during that time. Between 1 August and 16 September (final harvest date), leaves, stems, and canes lost a combined total of 5.3 g K vine-1 while the K content in the clusters increased by 6.9 g K vine-1. This indicates that approximately 75% of the increase in K by the clusters of these vines during the month and half before harvest may have been due to K redistributed from the above-ground vegetative organs during that time.