Scientists at SCRI say there’s mounting evidence that raspberries grown in polytunnels are bigger and taste better than those grown out-of-doors and unprotected from the elements.

Fruit was assessed from field and polytunnel sites at SCRI and at Blairgowrie in Scotland’s “fruit belt”. Without exception the taste in terms of sensory perceptions of sweetness and flavour intensity were significantly higher in fruit grown under plastic protection.

Size was also significantly increased in the case of soft fruit grown under cover. Comparisons between raspberries from the field and raspberries from polytunnels were made on the basis of weight, colour, sweetness, sourness and flavour intensity.

The research is being funded by the Horticultural Development Council and the Scottish Government under the HortLINK collaborative research scheme. The aim is to create a raspberry breeding programme that could dramatically expand the UK market for fresh raspberries.

The scientists used consumer tasting panels to assist their work: this part of the project also involved Strathclyde University. Much of the laboratory research depends on high-tech genetic mapping and marking techniques.

The aim is to develop new, high quality raspberry cultivars, adapted to modern production techniques that are naturally resistant to disease. The added advantage is that these new varieties will not require repeated doses of pesticides and fungicides.

The retail market for fresh raspberries is currently valued at over £50 million and has grown substantially over recent years. Persuading people to eat more health-boosting fruit is a Scottish Government priority.

The scientist leading the project, SCRI’s Dr Julie Graham, said: “New production methods, particularly growing under plastic protection, offer opportunities for season extension and improved quality of produce. And yet still only 6% of consumers in the UK eat fresh raspberries in any given season.

“Clearly there is still room for major expansion of sales, provided the industry can grow the kind of fruit consumers want.

“The barriers seem to be disappointment with the flavour, unattractive fruit and the short season of availability of the best quality fruit. What consumers – and therefore everyone else in the supply chain - are looking for are raspberries with sweetness, flavour intensity, and good fruit size and colour.”

Dr Graham and her colleagues say the challenge for plant breeders is to produce varieties with these desirable sensory characteristics using non-controversial techniques that can speed up the selection process and to enable growers to more quickly meet consumer demands and so expand the market. At the moment it can take more than a dozen years to produce a new variety.

A genetic map of the raspberry, developed at the SCRI and refined in a recent HortLINK project for root rot resistance, offers just such a technique.

Using the linkage groups that have been identified, it will be possible to establish the genetic basis of desirable fruit quality traits. And using molecular markers, it will be possible to screen for these traits without going through the lengthy and very expensive process of field selection of progeny from breeding programmes.

More information from:

Phil Taylor, Head of Communications, SCRI, Invergowrie, Dundee, DD2 5DA. Tel: +44 (0)1382 562731