Dry matter, nitrogen, potassium and phosphorus partitioning in blueberry plants during winter

Mature blueberry plants cvs. 'Elliott', 'O'Neal', 'Bluejay', 'Brigitta' (Vaccinium corymbosum L.) and 'Brightwell' (Vaccinium ashei Reade) were destructively harvested during mid-winter 2001 from a commercial orchard in Gorbea, Chile (38 degrees latitude S). Plants were divided into parts and analyzed for dry weight (DW), nitrogen (N), potassium (K) and phosphorous (P) concentration and partitioning. The crown had the largest DW in the plant (27 to 36%), followed by roots and 4-year-old wood. Nitrogen, P and K concentrations varied amongst plant parts. In all five cultivars the highest N, P and K concentration were found in floral buds (2.8% N, 0.3 %P and 0.8 %K for 'Brightwell'). As tissue aged, N, P and K concentration declined to 0.45 %N, 0.04% P and 0.15%K in 4-year-old wood 'Brightwell'. Total N, P and K partitioning in the plant was significantly correlated to plant part dry weight. Crown and roots were the largest N, P and K storage organs during winter in all cultivars. It is speculated that tissues with the highest nutrient concentration, such as buds, may be very important in supporting new growth.