Modern Soft Fruit Breeding 2007

Modern soft fruit breeding/industry – the way forward

The Scottish Society for Crop Research and SCRI hosted the soft fruit event ‘Modern soft fruit breeding/industry – the way forward’ at SCRI on 2 November 2007. The event was chaired by Andrew Logan.

The keynote lecture was given by Mrs Victoria Knight, Leader of the Raspberry Breeding Group at East Malling Research, East Malling, Kent. Mrs Knight retires early next year and kindly agreed to give her thoughts on how the raspberry industry has developed and what may lie in the future.

Changes in the raspberry industry

Photograph of raspberries in polytunnel Copyright: Vicky Knight, EMREntitled ‘Changes in the Raspberry Industry – a breeder’s perspective’ her lecture covered seven main areas of change all of which were inter-related and important. The very rapid change in the UK raspberry industry in the last 35 years has come about because of the combination of many different factors.

The first is changes in raspberry production. Over the last 30 years there have been significant changes in where raspberries are produced. Serbia, USA/Canada, Chile and Poland have all increased their production whereas Germany and the UK have had considerable reduction. In the UK, much of the reduction in output has been due to the decrease in the area down to raspberry in Scotland following the demise of open-field grown raspberries for processing.

The change worldwide is still taking place and by 2020 production in the following countries is expected to increase; Mexico, Morocco, Egypt and China whilst production in the Pacific North West and Chile is expected to decrease.

The next factor is the effect of introduction of new cultivars and the resultant extension of harvest season. Up until the early 1970s, nearly all production relied on summer fruiting cultivars which lasted for about four weeks. The season was further extended with the introduction of Glen Moy and Leo but was significantly extended by the release of Autumn Bliss, Joan Squire and Octavia.

During this period, there have also been significant improvements in the quality of summer fruiting raspberries, notably Glen Prosen, Tulameen, Glen Lyon, Glen Ample, Octavia, Glen Doll and Malling Juno. In autumn fruiting cultivars, Joan Squire, Polka and Autumn Treasure have improved quality attributes compared to Autumn Bliss but are later ripening. The current trend, especially with ‘private breeding’ consortia is to grow cultivars that can be ‘double cropped’. The characteristics of Octavia, Malling Juno and Autumn Treasure were described.

The last 30 years have seen major changes in production methods to get raspberries to the market place. In the UK, the introduction of cool chain marketing, use of overseas student pickers and plastic punnets in the 1970s; trickle irrigation, mechanical harvesting and primocane production in the 1980s; long cane production, use of polythene tunnels, fertigation, biological control and lidded, labelled punnets in the 1990s and development of doubled-cropping of primocane fruiting raspberries in the 2000s are of particular note.

Importance of labour

Photograph of raspberries being mechanically harvested Copyright: Vicky Knight, EMRLabour has always been a major part of UK raspberry production. Since the early 1980s overseas students, mainly from Poland were the mainstay of the UK hand harvested crops. However in the 2000s labour has been sourced from many other countries, such as Latvia, Lithuania, Ukraine and Russia. The introduction of non-indigenous labour is not restricted to the UK. For example in the USA Vietnamese and Mexican labour is used extensively.

Mechanical harvesting, especially for the processed crop was extensively trialled in the UK, resulting in the introduction of machines and varieties suitable for mechanical harvesting on some farms. Mechanical harvesting is still the main stay of the processed crop in the Pacific North West.

Long cane production was introduced to extend the season in the UK and used in Spain for early production. Although expensive and requiring the correct handling, improvements in plant quality means that long cane production has a place in the market. Season extension and fruit protection using glass, and to a much larger extent, polythene tunnels has revolutionised fresh fruit production.

The development of producer organisations in the UK and Europe has had a major role in shaping the raspberry industry. The main organisations operating in the UK were summarised.

Breeding raspberries is a long term exercise but the number of breeding programmes worldwide has reduced considerably in the last 30 years. Most were public breeding programmes but now many are either fully private or a part private/part public funded.

Mrs Knight raised concern that with the privately funded organisations there is now little or no exchange of germplasm, which was previously one of the main drivers in the public breeding programmes.

The lecture also addressed the possibility of genetic modification (GM) in raspberry. All GM breeding has apparently stopped, even in the US where GM-Meeker had been planted. However, the use of molecular markers is still being researched and is used for fingerprinting cultivars, identifying hybrids, in taxonomic research and assisting with breeding. Markers that have been identified and mapped include: SCRI – root rot resistance; Cornell (USA) – root rot resistance; EMR – aphid (A1) resistance and dwarfing.

Marketing of raspberries has also seen major changes. Berries are being actively promoted and this has greatly increased the public’s awareness and interest in healthy eating. Improvement in pack design and incorporation of berries, including raspberry, into drinks and juices, snack bars, dairy products and dried fruit have all improved sales.

Image of fruit and smoothie drink Copyright: Vicky Knight, EMRThe final area Mrs Knight covered is the interest in the effect of consuming raspberries on health and wellbeing. They have been identified as a good source of several chemicals reputed to be amongst the best defence against a range of common diseases. Studies are ongoing to confirm if these bioactive molecules are functioning in humans. As long as unsubstantiated claims are not made, raspberries can be promoted as part of a healthy, varied diet and there is a strong future for the UK raspberry industry.

Other presentations

The keynote lecture was followed by two short presentations.

Screening for winter chill requirement in Blackcurrant
Lyn Jones (University of Dundee) and Rex Brennan (SCRI)

Image of blackcurrantsProfessor Jones introduced his presentation with the question, ‘Why is winter chill important in blackcurrant?’He answered this by explaining that:

  • chilling is essential to satisfy dormancy requirement for optimal flowering and hence fruiting
  • chill affects flowering date and spread of flowering
  • climate change is leading to less chill and hence weaker flowering.

Therefore the aim of this project is to select blackcurrant genotypes that will perform well even in a warmer future. He continued by illustrating some of the chilling units that have been used in the past.

Previous research has estimated the accumulation of chill as the amount of time plants are exposed to temperatures below 7.2oC and were used to calculate the chill units, using natural chilling in the field. The approach that will be adopted in this project will rely on much more controlled chilling.

The potential advantages will be more reliable results independent of the actual weather conditions in any year; a reduced need for multi-site/multi-year trials; and therefore quicker high-throughput screening that will also allow precise definition of the chill response function for any species. This should lead to identification of cultivars that will be able to cope with climate change and be tailored to specific geographical regions.

Breeding for healthier rasps - new approaches, old problems
Gordon McDougall (SCRI)

Image of raspberriesBreeding targets for any fruit crop are complex and adding ‘human health’ to this list increases the difficulty for breeders. Dr McDougall reviewed the work already being done and showed that there could be considerable variation in anthocyanin content from a single breeding cross. However quick, sensitive and effective methods have been developed to select for healthy components in future cultivars.

The potential benefit to an increasing number of human disorders is being added to all the time. Two chemical groups have been shown to have possible effects, the anthocyanins and ellagitannins. In model systems, the former appear to be effective in managing cardiovascular disease (although the mechanism is still not fully understood) and the later appear to inhibit cancerous cells, especially in the gut.

Breeding to specifically increase levels of either of these compounds may have an important effect on either the taste or the colour of the resultant fruit and would the consumer accept this? It may be possible to modulate levels to increase beneficial effects but without greatly affecting colour or taste.

Poster presentations

A range of poster presentations were given following the speakers.