Development of field management protocols for Atlantic rose hip production

Roses of the genus Rosa are found growing wild throughout the Atlantic Provinces in a multitude of different habitats. Rose hips, the marketable product from these roses, are a rich natural source of bioactive compounds useful in the pharmaceutical industry. In 2004, two wild rose field experiments were established in Prince Edward Island. Experiment #1 was established at the Agriculture and Agri-Food Canada Harrington Research Farm, while experiment #2 was created on private land in the Argyle Shore area. The sites chosen for the experiments differed in soil conditions, microclimate, and the number and isolates of the rose plants used. Planting stock for these experiments was propagated from numerous wild rose (Rosa virginiana x carolina) isolates collected from populations throughout Prince Edward Island.

The experimental design for experiment #1 was a 3 x 3 x 2 factorial with 800 plants in a randomized complete block design, and four replicates of each treatment. Treatments were applied at planting and included: in-row mulch (none, bark and straw), in-row fertility (none, compost and fertilizer), and inter-row management (tilled and sod). The experimental design for experiment #2 in 2004 was a 3 x 2 factorial with 560 plants in a randomized split-block design, and eight replicates of each treatment. In-row fertility treatments (no fertilizer and fertilizer) were not included in the initial design for experiment #2, and were added in 2005. In-row mulch and fertility treatments were reapplied to both experiments in 2005. The objective of this study was to investigate the effects of several field management practices (in-row mulching, in-row fertility, and inter-row sod) in the establishment of a commercial rose hip plantation in Atlantic Canada. Data collected from both experiments included: mean shoot length, shoot diameter, number of branches per shoot, number of shoots per plant, plant spread, yield of rose hips per plant, and percentage of rotten and failed rose hips.

Mulching had a positive impact on several aspects of rose plant growth, resulting in larger shoots (length, diameter, and number of branches) and greater plant spreads for rose plants than no mulch. Mulching did not increase the number of shoots per plant, and in some instances had the opposite effect. Straw and bark mulches also improved plant nutrient uptake of P and N, but had no effect on rose hip yields in either experiment. Straw mulch was the most effective in-row mulch treatment for promoting plant vegetative growth in experiment #1, while bark mulch was the most effective in experiment #2.

Fertilized plants in experiment #1 had greater vegetative growth (significantly higher values for shoot length, branches per shoot, and plant spread) than plants with no fertilizer or compost treatments. The compost used in experiment #1 had clearly positive effects on soil fertility, but not on plant growth or productivity. Fertilized plants in experiment #2 had more shoots and greater plant spreads than did plants with no fertilizer. Use of fertilizer increased plant growth in both experiments, and rose hip yields in experiment #1.

Tilled inter-row areas led to a larger mean increase (from May to September, 2005) in shoot lengths, diameters, and plant spreads than for the inter-row sod treatments. Biological yield of rose hips was also significantly lower in inter-row sod treatments when compared to tilled treatments in experiment #2. Inter-row sod increased plant uptake of P in both experiments, but was not as effective at promoting plant growth and rose hip yields as the tilled inter-row treatment used in this study.

In general, the results from this study showed that wild roses responded very well to agricultural management. There was excellent survival of wild plants after transplanting, with only 2 deaths from the more than 1300 rose plants grown in these experiments. Regardless of the original collection source of wild plants, the plants displayed a similar growth pattern with few phenotypic differences under Prince Edward Island growing conditions. When these wild plants were removed from their natural habitat and grown in an agricultural setting, they established well and most began rose hip production in their second season, earlier than in published reports from other countries. The creation of a rose hip plantation is a long-term venture, and the rose plants used in this study are expected to reach full yielding potential only after four or more years of non-irrigated growth. The knowledge gained from this research will be a part of a long term project for establishing wild roses as an alternative agricultural crop for Atlantic Canada.