A British plant breeding breakthrough could help eradicate one of the most common threats to swede production around the world.
Two new Elsoms swede varieties available to growers in 2022 will be the first ever to include genetic resistance to the yield and quality sapping disease Brown Heart, says Elsoms Brassica Crop Manager, David Clay.
Teviot and Derwent have been tested extensively in field conditions across the UK and have achieved consistently high yields and quality without any incidence of Brown Heart, he explains.
“Brown Heart has been a problem for growers for many years with potentially devastating losses including unmarketable roots and field yield reductions of up to 40% being commonplace.
“The problem is the disease cannot be seen until the crop is harvested and by then it is too late to do anything about it.
“Brown Heart results from stress conditions, particularly lack of moisture at key times of the growing cycle, and with summer droughts now becoming more prevalent in many parts of the country, it is a problem that is likely to get worse.
“For some swede growers, production has unfortunately become a bit of a gamble and every variety bred to date is susceptible.”
Once in the crop, there is little that can be done to prevent the condition in terms of crop management, points out Mr Clay.
“Slower growing varieties have suffered less historically, and Boron deficiency is also thought to contribute to the problem, but even if you add Boron its uptake is seldom efficient so the condition persists.
“Over the years we have managed to breed swedes that have significantly improved quality, colour, shape and yield but Brown Heart resistance has eluded the industry until now.”
Richard Tudor, head of research and development at Elsoms, says building Brown Heart resistance into the new varieties has taken many years of talking to growers, patient plant breeding and transferring promising trial results into consistent field success.
“It all starts with the customer. We listened to their views about Brown Heart, how it affected them and the problems it gave them with marketing the crop. All said the condition was the number one problem they faced with commercial swede production.
“The first step was, therefore, to screen all the material we could source to find the lines least affected and establish why this was the case. This enabled us to select the best parent lines to create a new generation of hybrids with Brown Heart resistance.”
Working with York University, researchers were able to identify candidate genes we believe are providing resistance to Brown Heart.
“The great news for growers is that in seven years of trials in various conditions, in multiple locations and even when trying to force the condition on crops, we have never seen a single case of Brown Heart in Teviot or Derwent.
In one challenging trial in the Borders several years ago, every commercial variety developed Brown Heart apart from Teviot and Derwent. But Elsoms says in pre-commercial trials of the new varieties involving 300,000 plants grown in the field, not one developed Brown Heart.
With the most progressive swede breeding programme in the UK, Elsoms was the first to introduce hybrid varieties to the market in 2008 with the introduction of the variety Tweed, adds Mr Clay.
“Tweed introduced previously unheard-of levels of uniformity to the crop, which combined with high yields, allowed far more of the swede crop to be in specification for the retail market and consequently resulted in higher pack-out.”
Higher pack-out allows growers to get more production from each hectare and therefore reduce production costs associated with potential land rent, growing costs and netting so the introduction of hybrids has brought benefits to swede growers.
Brown Heart resistance adds significantly to the trait set of the hybrid varieties, says Mr Clay. It is something he believes will be welcomed by all swede producers.
“Teviot and Derwent are real breakthrough varieties and we’re very proud of them. They are genuine British-bred world firsts.
”Interest from the trade has already been phenomenal and we’re hoping for great things from them.”