Domestic production of raspberry covers around 50% of the wholesale market, but with more than 90% of the harvest in July and August. Both industry and market want a higher and more stable access to inland raspberry also in June, September and October. Furthermore, there is an ambition to establish a blackberry production supporting the market from June to October. The project 'RobustRubus' will therefore develop new solutions for economically and environmentally sustainable production of raspberry and blackberry. To achieve this, RobustRubus will i) introduce new, high-quality cultivars adapted to Nordic climate and light conditions; ii) improve the understanding of environmental reactions in raspberry and blackberry cultivars for rapid and economically sound adaption to new production systems and environments; iii) introduce new, locally produced substrates to reduce the use of peat and adapt watering/fertilization (fertigation) regimes to such media; iv) introduce automated tools for fertigation; v) introduce sustainable means to replace synthetic chemicals and subsequently reduce resistance development; vi) based on the obtained interdisciplinary results further develop existing platforms for interaction among growers, other industry, advisors and researchers for application of new technologies and achievements; and vii) offer internships and thesis subjects for students and a postdoctoral scholarship.
For three seasons, long-shoot plants of 18 varieties of raspberry and 10 varieties of blackberry have been imported and grown in a pots in a plastic tunnels. Yield and shoot architecture have been recorded, and berry constituents have been analyzed. Several sensory tests have been carried out during the seasons in collaboration with the project partners. Norwegian-produced long-cane plants have been tested in trials for three years and compared with imported plants. Experiments have been carried out in controlled climate with varieties of blackberry and raspberry for studies of plant growth and development. Results have ben published in a MSc thesis and in two scientific articles. Experiments have also been carried out on the effects of different substrates and fertilization strategies for growing long-cane plants of the raspberry variety Glen Ample. The preliminary results show that a substrate consisting of 50% wood fiber and 50% peat gives comparable results as with cultivation in standard substrate such as peat and coconut and can be a good alternative in raspberry pot production. The effect of fertilization strategy on the berry contents will be analyzed. Raman spectroscopy has been tested and used to investigate berry taste and chemical composition of the berries from different varieties. The taste of the berry was assessed by a taste panel and was analyzed for sugar and acid content. The collected data were correlated with the Raman spectra using chemometric methods. The prediction model revealed opportunities for using Raman for accurate analysis of sugar and acid in the berries, as well as a relatively good assessment of taste. Results from tests with varieties, substrate and fertilization are disseminated in popular scientific articles in grower magazines.
Root masses used for propagation, dormant detached flowering shoots and flower induced long cane plants of raspberry were steam treated at 44°C for different exposure times. Steam treated roots of four raspberry cultivars produced as many cuttings as non-treated roots. Bud break of steam treated detached flowering canes was delayed by 2-4 days, and number of viable buds was slightly reduced following steam treatment. However, when steaming long cane plants, many buds were damaged, and yields were significantly reduced. Two fungal species in the black root rot complex were eradicated from the root masses. Steaming for 2 hours killed 90-95% of overwintering leaf and bud mites and eradicated them after 4 hours. No eggs of raspberry aphids hatched after 2 or 4 hours steaming. Thus far in the project period, it may be concluded that root masses tolerate the steam treatments, but adjustments in temperature and/or exposure times must be made before long cane plants can be steam treated commercially. Brief pulses of overhead water irrigation 4 times per day reduced the population of two-spotted spider mites with approx. 50%.
Experiments with varieties, plant spacing, pesticides for removal of new shoots in the pots, and examination of shoot diseases in the field have been investigated in growers fields in different parts of Norway. An economic calculation is being prepared, after data collection from different cultivation systems. This will provide data for a life cycle analysis and provide guidance for economically sustainable berry production. Project meetings and field days have been held during the project period, and results have been disseminated continuously to the project partners and others in the industry nationally.
Over the recent years, the berry industry has received an increasing request for more domestically produced raspberry for fresh consumption outside the current major harvesting season in July and August. There is also a market demand for an increase in blackberry production from near nil today. The primary focus of RobustRubus is therefore to provide the basis for extended-season cultivation in high plastic tunnels of both crops, i.e. harvesting from June to October. However, results from the project may also be used in the traditional open-field production. The project will investigate how we can better exploit high-quality and high-yielding annual and bi-annual cultivars adapted to Nordic climatic conditions. For a rapid and economically sound adaptation of the cultivars, we seek to advance the understanding of their reactions to temperature, light and growth media. To ensure the establishment of wood fibre as a viable growing media, watering and fertilization will be thoroughly adapted to cultivars, growth phases, time of the season and environmental conditions. A life cycle assessment (LCA) will be performed to compare environmental sustainability among growth media and high plastic tunnel vs. open field production. Both in transplant and fruit production of the two crops, it is expected that RobustRubus will contribute to a substantial reduction in current use of synthetic chemicals by introducing several non-chemical means in the control of fungal pathogens and mites. For rapid transfer of new knowledge and ensure economically viable innovation, the advisors in the project will have a continuous communication with the growers and pay weekly to bi-weekly on-site visits at production sites. The project will contribute to recruitment of the industry by yearly offering student internships for work experience and thesis subjects based at research stations and/or regional advisory offices, and a postdoctoral fellowship in plant pathology will also be offered.