Early maturing oilseed rape varieties may be ready for harvest much earlier than official Recommended List ratings indicate, according to latest findings from Masstock’s Best of British Oilseeds initiative.

Observations from a series of trials at the firm’s SMART farms in Northampton and Yorkshire last year found that Excalibur (rated 7 for earliness of maturity in HGCA lists) was ready to harvest a week earlier than the standard variety, Winner (RL rated 6).

Most of the other six varieties studied matured around the same time as Winner, says R&D manager, David Langton.

“HGCA Recommended List earliness of maturity ratings have always shown clear varietal differences, but the extent of these and the management opportunities they offer growers has only really just become apparent.

In our observations last year, Excalibur was the one that stood out most.”

RL ratings may not always show the whole story when it comes to predicting crop maturity, he continues.

These figures are based on 1-9 scoring of the senescing canopy just before swathing or desiccation (1 is green and pliable, 9 is bleached and brittle).

It can take between 10 days and three weeks to move through this range of maturation, depending on conditions, implying that each score represents between one and three days.

“Our work shows that the difference in actual harvesting date between a single RL earliness score could be as much as seven days.

So including an early maturing variety in the cropping mix could make all the difference for many growers.”

Being able to start OSR harvest sooner reduces the risk of it clashing with wheat harvest, lowers the chances of weather disruption, improves timeliness of following cultivations and crop establishment and gives more time for grass weed and volunteer control, he says.

Late season

“Growers in the north of England and Scotland are likely to welcome this attribute even more than most, with the relative lateness of their season and their particular vulnerability to poor autumn weather.

“Where you have got a large acreage, growing a range of varieties with different speeds of maturity could also be a good way of spreading workloads and harvest dates.”

Mr Langton acknowledges that early maturity needs to be combined with relatively early flowering to ensure yields are not compromised by a reduction in the grain fill period.

In this trial, Excalibur yields (about 5t/ha) were similar to the slightly later maturing Castille (RL rated 6 for maturity).

“Providing the crop is harvested at the right time, there shouldn’t be any yield loss (due to problems like pod shattering) compared to later maturing varieties,” he notes.

Looking forward, he says there could be a slight trend towards earlier maturing varieties, but in many cases breeders are focusing on a number of other varietal characteristics and not maturity.

“Monsanto’s new variety, Excel, for example, is later maturing than some current varieties.”

For more information on Masstock’s Best of British Oilseeds initiative, which is investigating the management factors that will deliver higher oilseed rape yields, see www.masstock.co.uk

paul.spackman@rbi.co.uk