Research Highlights
Nutrient Assimilation and Allocation
In addition to examining seasonal growth and carbohydrate dynamics, the previously mentioned experiment also examined the seasonal nutrient assimilation and allocation dynamics of the wild blueberry during the sprout and cropping years of production. Results from these studies have indicated that with the exception of supplying adequate nitrogen levels for the initial two months of the sprout phase of production, the wild blueberry is under nitrogen deficient conditions throughout the remainder of the sprout and cropping phases of production, the deficiencies in nitrogen are present throughout the roots, shoots, and rhizomes, and these deficiencies are particularly apparent during the cropping phase of production.
The net results of these finding has been implementation of additional trials to examine the influence of different nitrogen forms (e.g., ammonia versus nitrate formulations), application dates, and application frequencies (1, 2 or 3 times during the 2-year production cycle). From the nitrogen formulation perspective, results have indicated that ammonium sulphate is the most favorable form of nitrogen to use in wild blueberry production with minimal effects on the mycorrhizal association of the wild blueberry, improved phosphorous uptake, improved stem vigor (the stems are less spindly), increased leaf tissue nitrogen levels, and increased yields. The effect of applying multiple nitrogen applications at various intervals throughout the season has indicated the impact of developmental stage, and frequency of application on growth, development, and yield. Results are indicating (there are 2 more trials to be harvested in 2002) that the optimal timing for nitrogen application consists of an initial application of a broad spectrum fertilizer in the spring of the sprout year (e.g., a 14-18-10), followed by an additional application of nitrogen in late July (i.e., after black-tip has commenced). Depending on the soil type (i.e., light textured soils) and inherent plant vigor, there may continue to be a need for crop-year applications of nitrogen. In addition, the net impact of different nitrogen application methods (i.e., soil-applied fertilizer versus foliar-applied urea) need to be examined to determine the proportion of nitrogen that is being used (i.e., nitrogen use efficiency), the influence of these treatments on the various yield components (i.e., stem densities arising from the rhizomes or improved floral bud quality attributed to increased carbohydrate and nitrogen content within the floral bud), and the most economically feasible means of applying the additional nitrogen applications.
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Seasonal Growth Dynamics
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