23 January 1999

reduced rates on the cards

Seed rates could be the crucial element in growers decisions to grow hybrid wheat. Dick Palmer reports on new research.

DONT be put off by high seed costs for hybrid wheats. If early trial results from Independent Agri-culture are anything to go by, hybrid seed rates could be reduced by as much as 20%.

At Manor Farm near Malton in North Yorkshire, the shop window for company agronomic policy, plots of conventional Riband were drilled at 100, 200, 300 and 400 seeds/sq m last year, and at three-weekly intervals starting 10 September.

Alongside them, hybrid wheat variety Cockpit from Monsanto was established at 20% lower seed rates ie 80, 160, 240 and 320 seeds/sq m. "So far the hybrid optimum appears to be 160 seeds/sq m, drilled around 1 October," says Chris Rigley, senior agronomist with Independent Agriculture, part of the American Agri-Products company.

"Results from a single years trial must be viewed with caution, especially given the unusual growing conditions during the 98 season, but we are sufficiently confident to continue seed rate and drilling date comparison work," says Mr Rigley. "Seed rates must reflect seedbed conditions at the time of drilling and early results would suggest that hybrid seed rates could be reduced by at least 10-15% compared to conventional varieties."

Hybrid vigour

"Hybrid vigour was astounding throughout the trial," continues Mr Rigley. "With favourable seedbed conditions last autumn we didnt measure any difference in the percentage establishment but hybrid plots established much faster reaching optimum tiller populations two to three weeks earlier than Riband."

Also the hybrid variety appeared not to exhibit take-all symptoms to the same extent as Riband. "Although it is too early to draw any firm conclusions," cautions Mr Rigley. Unfortunately, Cockpit succumbed to yellow rust earlier than Riband, probably due to its denser canopy but thats likely to be a varietal problem. "Hybrid technology is still in its infancy," admits Mr Rigley. "Cockpit is the first of many varieties, which are bound to get better and better."

Early rust was kept in check using an additional tebuconazole treatment, otherwise both varieties received the same robust fungicide policy of Landmark strobilurin at stem extension and flag leaf followed by Amistar as an earwash. "The yield comparison is all important at this stage of trials," says Mr Rigley, "so disease must be kept at bay.

Hopefully, the right seed rate and drilling date combination should reduce growth regulator requirement according to variety. In the trial, hybrid Cockpit stood as well as Riband.

"There is a future for hybrids provided they arent too expensive to grow under present economic pressures, and that further advances are made in the breeding programme," believes Mr Rigley.


Seeds / sq m Sowing date

10 Sept 1 Oct 22 Oct

Hybrid Cockpit

80 8.77 9.46 9.59

160 10.44 11.95 9.49

240 7.49 7.90 9.66

320 8.99 8.28 8.84

Conventional Riband

100 5.99 9.01 7.7

200 6.49 6.76 8.29

300 3.69 3.11 4.91

400 4.59 4.89 5.86

Soil type – Clay loam

Rotation – Second wheat

Source: Independent Agriculture