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UK: NIAB onion trials - Spring-sown varieties trialled in Suffolk

Hybing was clearly the earliest brown this year, in a season running two weeks late, Claire Shaddick reports.
 
Four onion varieties closely competed to be the earliest brown in the National Institute of Agricultural Botany's (NIAB) main spring-sown variety trials last year. But the industry standard Hybing is clearly the earliest this year in a season that is running about two weeks late.

The trial was drilled in good soil conditions on 17 March but the cold spell that followed caused plants to stand still. Getting enough irrigation onto the plots during the heat and dry of midsummer was also a challenge, says NIAB vegetable consultant Mike Day.

At one of two NIAB trial sites - PG Rix Farms on the Suffolk/Essex border - Hybing reached 35 per cent fallover by 19 August. But in Norfolk, fallover was 68 per cent, followed by Vision on 25 per cent. "Hybing has also bulked up," says Day. "It has good shape and yield but is not a variety for long-term storage."

Vision, on the other hand, now in its third year in the main trials, was the highest yielding last year on both trial sites, producing the equivalent of 75 tonnes per hectare at PG Rix and almost 68 tonnes/ha in Norfolk. "It's outstanding for storage, having broken the mould for storability for early varieties," he adds.

NIZ 37-71 is early but the bulbs seemed to be lacking in size by the time of an NIAB open day at the Rix site on 24 August. "It makes a decent shape, has a thin neck and had a good yield last year (more than 71 tonnes/ha on the Rix site)," says Day.

Attraction is not quite as early as it was last year when, entered in the preliminary trials as ONL295, it came in as early as Vision. It stored as well as Vision, too. Yields averaged almost 71 tonnes/ha across both sites.

Motion and Hybound - both in the main trials for the first time - Centro, Premito and Sunnito are all in the early maincrop slot.

In the preliminary trials last year, Motion was judged to have well protected globe-shaped bulbs with erect foliage and early vigour. In maturity, it is going to settle down between Wellington and Napoleon, says Day. Yields were good last year, especially on the Norfolk site, and it "stored very well".

Hybound has slightly flattened globe-shaped bulbs and yielded well at both sites last year, with a mean of 68 tonnes/ha.

Centro produces uniform, well protected globe-shaped bulbs and is capable of high yields. Storage performance has been above average in ambient store. Commercially available for three years, it is the first variety to emerge from a Nickerson-Zwaan development programme that focuses variety screening on UK growing conditions, rather than seeing whether varieties bred for European markets would work just as well here, says range manager John De Soyza.

"Centro consistently produced above average yields in every situation, be it light sand or peat fenland, in warm or cold years," he adds. Its root vigour helps it to get away in a difficult spring and meant it coped better with the long dry spell this year, he adds.

Premito yielded well on the Essex site last year, with almost 75 tonnes/ha of well protected, globe-shaped bulbs. It stores better in ambient conditions than in a cold regime.

Sunnito is similar to Premito, both being bred by Seminis. Last year it had an early mid-season maturity with average yields of slightly flattened globe-shaped bulbs.

Santero has maincrop maturity and only average yields, but its main selling point is downy mildew resistance. "It has come into its own in the organic sector," says De Soyza. "It is not as high yielding as Centro but offers security against the disease." It is now available as a set from the English Set Company. Nickerson-Zwaan's aim now is to introduce resistance into earlier varieties with longer-term storability, such as NZ 37-82, which is in the preliminary trials this year.

Hylander is also one of the new generation of mildew-tolerant varieties, in its second year in the main trial but yet to be tested by a bad mildew year. "I have seen it in organic situations and it does stand up," says Day. "But there is some payout in yield." Yield last year was among the lowest of all brown varieties trialled. Timing is between Arthur and Sunskin.

Sunskin is the oldest hybrid in the trials, NIAB having first seen it in 1999. "It had maincrop maturity then," says Day. "Now it is probably regarded as late maincrop because the whole crop is getting earlier." It suffered last year from poor establishment and below-average yields on both sites - but it does store well.

Sakata's Pegase and SVS 69497 from Seminis are in the preliminary trials this year for a second look. Pegase has a similar early maturity to Vision and produces a very large, elongate bulb with a thin skin, which would suit processing. But based on one year of results it does not seem to store beyond February/March in ambient storage. Last year's yield, of 87 tonnes/ha averaged across the two sites, was exceptionally high. Its lack of wax on the leaf may, however, make it more susceptible to mildew. "It did get more mildew than other varieties last year, which is a worry," says Day.

SVS 69497 produces slightly flattened bulbs with a mid season maturity that stored well. Yields averaged almost 72 tonnes/ha last year.

Also in the preliminaries are Sherman and Hytide from Bejo and three Nickerson-Zwaan varieties, including NIZ 37-84, which has a strong top and had bulked up well.

At 60 per cent fallover on the site by 19 August, Sherman looked to be the earliest variety in the field. But the bulb's distinctive Spanish shoulder may be a disadvantage, according to Day.

Red varieties

In the main trial of red varieties this year are Grenada, Redspark and Red Tide, with Red Baron as the industry standard.

Redspark is the most successful of hybrid reds introduced in the past 10 years, in uniformity, good colour and decent yield, says Day. But its good storage is its main characteristic. "It's the best storing red we've had on the late side of maincrop," he says.

Red Tide is earlier than Red Baron, with 35 per cent fallover at the Essex site by 19 August compared to two per cent for Red Baron, and is about a week earlier than Redspark.

Judging by last year's preliminary trial, Grenada has decent shape and yield, averaging 53 tonnes/ha across both sites, and early mid season maturity. Problems with the seed stock have led to a thin stand this year, however.

Four red varieties are in the preliminary trials - Garnet and Red Queen from Allium & Brassica Supplies (ABS), 9.125 from Allium Farms and Renato from Nickerson-Zwaan.

Garnet has been trialled before but grown from a set. ABS promotes it as featuring a more regular shape and more single centres than Red Baron. It stored very well as a set, says NIAB vegetable specialist Bruce Napier. This bodes well for the drilled crop, which by its nature stores better.

Red Queen was trialled in the preliminaries last year as ABS 203, where it had early mid season maturity. ABS says its bulbs are more globe shaped than Red Baron, with a slightly paler skin colour. With very good early vigour, 9.125 was showing clean foliage with no hint of tipping back.

Renato, seen for the first time, looks like slotting in between Red- spark and Red Tide for maturity. "It established well and is filling out nicely," says Napier.

Naked versus pelleted versus primed

The site at PG Rix Farms is also hosting an Horticultural Development Company-funded seed treatment experiment comparing three Bejo varieties, Hyfort, Hytech and Hybelle, sown as either naked, pelleted or pelleted and primed seed.

The aim is to settle the debate about whether the benefits of using pelleted or primed seed is worth the extra investment, says NIAB vegetable specialist Bruce Napier.

Seedlings from primed seed were first to emerge. "Plants got to the two-leaf stage about a week sooner," he says. "Maturity wise, we're not seeing any correlation with the seed treatments. Hyfort is the earliest."


Source: hortweek.com

Publication date: 9/27/2010


 


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