Glen Lyon raspberry

Derek Jennings, the breeder of so many of our new raspberries, tells us the story of Glen Lyon which for the past 20 years has been the main variety grown in Spain and exported to the UK.

When I was first involved with raspberries at the Scottish Crop Research Institute, the aim of Scottish growers was almost entirely to supply fruit for the processors. The high yielding varieties Malling Promise and Malling Exploit suited them well, but they had ambitions to extend to the fresh markets and this meant that varieties with firmer fruit were required. Malling Jewel fulfilled this purpose but it had its limitations. We therefore set out to build up the firmness of the fruit by combining genes from different sources.
 
First, the combination of Malling Jewel with Burnetholm gave us Glen Clova; Burnetholm being a popular variety which Lanarkshire growers used to supply fresh fruit to the Glasgow market. Meanwhile, workers at East Malling transferred genes from the black raspberry to the red raspberry to obtain a major advance in the meaty texture of the fruit, and they generously made their germplasm available to us. Glen Moy, Glen Prosen and Glen Lyon and later Glen Ample are all examples of varieties that this combination of three sources of texture improvement gave us.
 
Our work was also greatly helped by germplasm exchanges with Hugh Daubeny, the Canadian raspberry breeder. We were in constant communication and would frequently cross the latest selection from my programme with the latest selection from his. For example, we gave him our Glen Prosen and he crossed it with his Nootka to produce Tulameen, which is now probably the world`s most widely grown variety. At this time, the use of our Glen Clova variety had become very dependent upon the application of dineseb to control its excessive vigour, and growers were alarmed that the chemical was to become unavailable due to health fears. I rashly promised to breed them a variety with `built-in vigour control` and turned to Hugh for his variety Haida, which he had selected because its firm fruit and moderate vigour made it suitable for the strong growing conditions of British Columbia. Crosses of Haida with a close relative of Glen Prosen gave me Glen Lyon which inherited these features.
 
Glen Lyon initially did all that was expected of it, but we did not know that its moderation in top growth was associated with moderation in root growth. A sequence of drought years in the late 1980s revealed this short-coming and the variety suffered badly. Growers ploughed it out faster than they had planted it. However, it was about this time that the industry changed quite suddenly to production under irrigation in plastic tunnels. Not only did this solve the variety`s problems, but to a greater extent than other varieties Glen Lyon suited production in tunnels, particularly in the Spanish tunnels in Spain. The changes happened so quickly that it seemed like divine intervention. Glen Lyon was born again!
 
Glen Lyon`s yields are high in Spanish tunnels because its moderate vigour allows the tunnels to accommodate four rows of plants instead of three as in other varieties. Its picking costs are lower too, partly because its fruit is so well displayed and partly because its superior shelf-life means that it can be picked on alternative days instead of daily. It is common practice in Spain to continually cut all the new growth to the ground to improve yields and facilitate picking, and then to discontinue the practice in spring to allow new canes to grow and provide planting material for the new season. The latter is lifted for 45 days of chilling and canes are planted every three weeks to provide fruit for our supermarkets from November to April. The moderate top growth of Glen Lyon does not limit the new growth of these new canes like the vigorous top growth of a variety like Tulameen does. For all these reasons, Glen Lyon became the main variety grown in Spain and it has retained this position for nearly 20 years, even though the supermarkets would prefer a variety with bigger fruit if a suitable one were available.
 
There were several incidental improvements provided by the diverse parents used in this process of building up fruit firmness. Burnetholm, for example, is the only known variety which carries the recessive gene for spinelessness, and it has contributed spinelessness to many new varieties It also contributed its unique aromatic flavour to the fruit of the varieties Glen Moy and Glen Magna, whose flavour has something extra compared to other varieties. Fruits of the variety Haida are glossy and have improved skin strength: fruits of many American varieties have these features whereas UK varieties are better for texture strength. The black raspberry gave us a more stable form of aphid resistance.
 
The progress described also shows the benefits of a free exchange of germplasm among breeders. Not only is the genetic diversity of the raspberry spread more widely, but distant crosses usually show greater vigour and higher yield potential. Such benefits are rare in the present day trend towards restrictive commercial breeding.  
 
 

Derek Jennings