Growth responses of three New Zealand northern highbush blueberry cultivars (Vaccinium corymbosum) to nutrient availability

Responsiveness of three New Zealand northern highbush blueberry cultivars (Vaccinlum corymbosum L.), 'Nui', 'Puru' and 'Reka' to three degrees of regulated nutrient availability was examined: 1) in the control treatment, no nutrient was added, 2) in the solid fertilizer treatment, a standard commercial fertilizer was applied at the start of the experiment, the release of nutrients being dependent on the properties of the fertilizer and environmental conditions, and 3) in the fertigation treatment, a dilute solution of readily available nutrients was supplied daily. Treatments were applied from mid-May 2001 up until plants were destructively harvested in mid-September 2001. For all three cultivars, accumulated dry matter in the fertigation treatment was 2 to 3 times that in the solid fertilizer treatment, whereas that in the control treatment was the least. 'Nui' had the lowest total dry matter levels, they were significantly higher in the fertigation treatment though because of increases in aboveground growth. The root system was unresponsive to the varying nutrient levels applied. 'Reka', the fastest, growing cultivar, had the most responsive root system, its dry weight increasing 2.9 fold in the fertigation compared to the solid fertilizer treatment, that of 'Puru' was intermediate. We concluded that there is potential to apply a finely regulated fertigation system to commercial blueberry production.