With the advent of long-storage varieties and improved storage technology – coupled with careful soil type selection, crop husbandry and harvest timing as well as suitable seasonal conditions – the UK onion industry is tantalisingly close to supplying home-grown onions year round.
“A decade ago we relied on eight to nine weeks of imports,” says Sam Rix, technical director at PG Rix, a leading Essex-based grower and supplier. “This year we imported brown and red onions grown in Spain to plug a two-to-three-week gap in UK supply.” To manage supply, G’s Growers has approximately 55,000 tonnes of storage made up of 25,000t of ambient and 30,000t refrigerated, including 2,500t of controlled atmosphere (CA) for late storage.Barry Standing, head of procurement, explains: “Using various systems and combinations, including ethylene and different ventilation management approaches, we can ultimately address long-term bulb quality, shelf-life and storage efficiencies.”
Alongside 9,000t of bulk onion storage, PG Rix has 10,000t of refrigerated box storage, including a new 2,000t store of 35t boxes at a cost of £800,000.
“We cherry pick the best crops to put in to our refrigerated box stores,” explains Rix. “This year we finished packing the 2015-grown UK crop on 15 July. This left us with just two weeks of imported brown onions from Spain before we were back in to newly-harvested overwintered UK production. Using good storage varieties, these refrigerated stores guarantees crop will last into mid-July. The more confidence we have in a variety, the longer we can push it.
“Syngenta’s long-storage variety Vision singlehandedly increased storage by two to three weeks,” says Rix. “The industry only needs to achieve another two to three weeks and it will have cracked 12-month supply of UK onions.”
According to Standing, often the best storage varieties have the worst uniformity – or can lack vigour, and vice versa. “Varieties are programmed to match the soil type, aspect, irrigation regime etc,” he says. “The most reliable results tend to come from Hybound, Centro and Hytech. Others giving good results in specific situations include Hypark, Motion, Vision and Bennito.
Ideal characteristics include good vigour, erect foliage, bulb uniformity, a globe shape, strong roots, single centres, fine necks, dry matter over 13 per cent and good storage as well as fusarium and downy mildew resistance.
“Obviously no one variety has all these characteristics and that is why care is taken to match the variety to the field in the context of the marketing plan,” explains Standing.
PG Rix constantly trials new varieties, working with seed and breeding companies to get ahead of the game – Elsoms, Syngenta, Hazera and Seminis. As well as five to six strip trials per year, Rix hosts the AHDB-funded NIAB drilled onion trial. “It is good to see how the newer varieties perform on our soil type using our agronomy,” says Rix.
“There is no tolerance in the retail market for stained onions – Class I pre-pack is where the returns are. Vision from Syngenta is the market-leading variety for early mid-season maturity and we are confident this variety will go the distance in store. Hybound, bred by Bejo, is another good variety with early maturity – however, in ambient stores it breaks dormancy earlier.”
According to Standing it is now technically possible to supply UK onions year round and has been for the past decade. “Ironically it is the change of emphasis onto price, from quality, that has provided marketing opportunities otherwise supplied with imported southern hemisphere fresh crop,” he says. “In principle, techniques now allow reliable UK maincrop Rijnsburger supply until mid July with the latest best quality and shelf life coming from CA storage. The growing of overwintered and early spring sets overlap the July supply, continuing to September when the new Rijnsburger crop harvest commences again.”
However, while technically this is possible, he says for it to be standardised, production and storage needs to be consistent and competitive. “Further developments and improved UK competiveness will be subject to growers’ ability to reinvest,” Standing says. “Production costs have risen year-on-year while returns have dropped significantly. This has focused growers’ attention on efficiencies, but ultimately their future may not be financially sustainable unless customers embrace the fundamental concept of reinvestment.”
Meanwhile, an interesting newcomer from Hazera Seeds, Fasto, is showing potential to help in the bid to supply UK-grown onion year round. An early variety, it is described as highly tolerant to sprouting, regrowth and rots.
In a 10-week accelerated deterioration store trial, carried out by Hazera, Fasto suffered no rots, no sprouting and produced a 100 per cent marketable yield. A range of established commercial storage varieties produced total waste levels of between nine and 28 per cent and corresponding marketable yields of between 72-91 per cent. Fasto was the only variety tested to also deliver the same improved results in ambient stores and was still marketable by the first week of June.
“This is an early variety offering good bulb uniformity and storability,” says Hazera’s John de Soyza. “Being early, Fasto can be harvested when conditions are better and offers the flexibility to be harvested early and yet stored long term.
“In contrast, later-maturing varieties run an increased risk of rain interrupting harvesting leading to skin staining. Fasto offers maximum flexibility for harvest and storage and reduces losses out of store.
“Hazera maintains 11 screening trials across Europe. Field observations show Fasto produces good clean broad foliage that stands up well against tipping and other issues.”
Keen to crack the 12-month supply and looking to move forward as fast as they can, both PG Rix and G’s Gråowers will be looking at Fasto next year.
After two years of successful strip trials, Hazera newcomer Chico has already found a place in the Rix programme with a 30ha field grown in 2016.
“Producing a nice globe-shaped bulb, good foliage and skin finish and good storage, it impressed me,” says Rix. “Chico is likely to feature more highly in the future.”
G’s is also producing 45ha of Chico in its growing programme.
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