Nerves ahead of what could be a make or break week for Europe's wheat rally dragged prices back from one-year highs on Friday.

In Paris, the best traded November wheat lot rose 2.3% to E152.00 a tonne in early deals, matching the best price for a next-but-one contract since June last year, but failed once again break above a level which has been identified by traders as offering technical resistance.

London wheat for November delivery rose 2.1% to £112.00 a tonne, the highest for a second-in lot since late July last year.

However, the grains reversed from highs in afternoon deals amid profit-taking ahead of what could be a crucial period for market watchers.

Next week is expected to bring first results of the wheat harvest in France, Europe's biggest producer of the grain, where farming co-operatives have been talking down yield prospects after a series of weather setbacks.

'Operators cautious'

Hot weather has raised concerns that some crops have ripened before grains have had a chance to reach their ideal quality and crop size.

Some crops also face the hazard of rains this weekend, just as harvest is starting in many southern areas.

"Operators remain cautious with a possible drop in temperatures and the expected arrival of stormy episodes in the next few days," Agritel, the Paris-based analysis group, said.

A UK trader told Agrimoney.com: "People have been talking down yields in mainland Europe. We will soon see what the real yields are, whether better or worse than expected.

"But at the moment, we are not in a situation of plentiful supply, compared to where perceptions were."

Besides Europe's weather challenges, a wet spring has devastated Canadian wheat prospects, by setting back sowings, while Russia's grain may fall as much as 17%, analysis group SovEcon said this week.

Ukraine delays

Pierre Begoc, Agritel's executive director, said that a rain-delayed start to the harvest in Ukraine, a major competitor to the EU on export markets, had also underpinned European prices.

"That has given some support to cash markets [in Ukraine]," he said.

In France, Agritel was expecting yields "the same as last year, or a little bit lower", although field data would make more accurate analysis possible next week.

Some traders have forecast weaker wheat yields after making comparisons with the barley harvest, where yields have been reported to be some 5-10% down on last year.

Paris's November contract closed at E150.25 a tonne, up 1.4% on the day, with its London equivalent ending 1.1% higher at £111.00 a tonne.