Growers should consider direct drilling courgette crops to extend their season, National Institute of Agricultural Botany (NIAB) vegetable specialist Bruce Napier has advised.
However, he urged caution due to the risk of weather damage and the as yet incomplete picture of how different varieties perform when grown this way.
Speaking at the NIAB's courgette variety demonstration day at its Cambridgeshire site last month, Napier said he had chosen to conduct trials of direct-drilled plants in addition to the main variety trial to fill an apparent gap in the information available to growers.
"There is pressure from supermarkets to provide UK-grown produce over a longer period and if you direct drill through polythene, as long as you do not get hit by frost, you can harvest a week or two before the main transplanted crop comes through," he said.
"So far it's a look-see, but I will push the seed companies to do a bigger trial on this," he added. "There's very little information from the seed companies themselves because they are targeting main crop material and won't necessarily know which is best suited to direct drilling."
The 10 commercial varieties were hand sown at double the spacing for the main transplanted trial through black polythene on 24 April. "It rained afterwards for a couple of months," said Napier. "They can rot in the wet soil at the seedling stage."
Resulting emergence varied widely, from eight per cent for Enza's Aretusa to 80 per cent for the Acceste variety from Seminis.
"There are still big differences between the varieties but the lack of seed treatment clearly makes a difference in adverse conditions," said Napier.
"It's a balance of risk and reward. The courgette is a delicate plant and even experienced growers can still get clobbered by a late frost - you have to approach with caution, perhaps trying it on a small area of the farm."
Syngenta crop specialist Nigel Kingston expressed some scepticism at the approach, saying: "Your biggest cost is your land and you don't want gaps (due to uneven emergence)."
NIAB courgette trials - Exhibitor varieties and recommendations
Besides yield and disease resistance, growers should consider plant habit, ease and method of harvesting and colour, size, shape and size of blossom scar in selecting courgette varieties, according to exhibitors at the National Institute of Agricultural Botany trials.
Syngenta crop specialist Nigel Kingston described the company's Milos as "upright, open, easy to pick - the developments from our breeding in France". Meanwhile, its Mykonos "hasn't yielded so well, but the fruit quality is outstanding - dark and cylindrical rather than bulbous".
Kingston admitted though that "specialist" varieties such as the long yellow Golden Glory and the round, scalloped-edged Sunburst "will remain niche".
Other breeders exhibiting were HM Clause, Enza, Nickerson and Seminis.