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Canadian Organic Science Cluster Success Story: Laying the foundation for organic black currant production
While black currant (Ribes nigrum L.) production is prevalent in Europe and New Zealand, it has been slow to take off in North America. However, with increasingly resistant cultivars, a recent interest in organic production on Prince Edward Island has arisen to satisfy a health-savvy Japanese market that prizes blackcurrant berries for their high vitamin C, antioxidant levels and flavor. However, organic production of this fruit is extremely limited globally, and the growing conditions in Atlantic Canada are starkly different from other countries. One of the key goals in black currant production is to quickly establish tall bushes that can be mechanically harvested. As with most crops, this means that an adequate supply of light, water, and nutrients is needed during the first three years to promote bush growth and then ultimately yield. In preliminary trials, it was observed that weed management was essential for maintaining leaf tissue nutrient concentrations and growth of newly planted currants. However, fertility weed management practices for organic production are not well known. We also wondered if flower management during years two and three could affect growth and yield of the bushes.
Two sites of blackcurrant cv. “Titania” were established on PEI in 2009 to measure the effects of deflowering and nutrient rate and timing on the growth, yield and nutrient uptake of establishing plants. Seven fertility treatments were applied which included four spring rates and one summer application and two combinations of spring and summer applications. Black plastic mulch was used to prevent weed growth. Nutrients were applied as a mix of pelletized poultry manure and crab meal. In four of the fertility treatments, we had plots that were either flowered or deflowered.
One of the most important findings related to site effect, where one site with higher phosphorus and potassium levels had much better growth and yield and little response to the fertility treatments compared with the other site with lower phosphorus and potassium and a stronger response to the amendments observed. Hence background soil fertility is a very important factor, and can override any expected benefits from amendments applied on the basis of nitrogen. Addressing phosphorus and potassium deficiencies in establishing currants can lead to more than doubling the yield bush growth and yield of the currants.
Deflowering of black currants as a method of promoting early growth and yield has never been tested, according to our literature reviews. Preliminary results are showing very interesting trends that are again site dependent. Where background fertility (especially phosphorus and potassium) was higher, one year of deflowering promoted yield. Where background fertility was lower, deflowering promoted greater bush growth.
The results of this work will have significant impact on the feasibility and profitability of growing black currants in PEI for high value markets.
© 2012, Organic Agriculture Centre of Canada (OACC)