Effect of dose and timing of application of different plant growth regulators on lodging and grain yield of a Scottish landrace of barley (Bere) in Orkney, Scotland

The effects of dose and the timing of the application of three different types of plant growth regulators on lodging and grain yield of a landrace of barley (Bere) were investigated. Results indicated that the application of full dose of plant growth regulators at Zadoks growth stage 31 had improved lodging resistance by reducing the stem length. Amongst plant growth regulators Upgrade caused the highest reduction in stem length and lodging index compared with other plant growth regulators while Adjust was the least effective plant growth regulator. The results indicated that Upgrade was less effective in lodging control at the higher nitrogen level (90 kg ha-1). Although this plant growth regulator improved lodging resistance, grain yield was not enhanced in any of the trials. This outcome was due to a delayed lodging and/or absence of severe lodging in the control plots. Further investigations on the effect of timing of lodging incidence on grain yield would be useful extension of the present study. A separate trial investigating the effectiveness of Upgrade in lodging control under a range of nitrogen levels is recommended.