The influence of sowing date and nitrogen on yield determination in winter barley in north-east Scotland
Detailed field trials were conducted over 4 years to investigate the effects of sowing date, nitrogen applied in the autumn and in the spring and growth regulator on the yield and yield components of Igri winter barley. Overall there was a yield plateau from sowings made between the end of August and the middle of September, but thereafter there was a yield decline with delayed sowing, the steepness of which, related to how early reduced temperatures caused growth to cease in the autumn. The detrimental effects of late sowing were only reduced in one year by increased nitrogen application in the spring and even then the benefits were too small to be of practical significance. The wide ranging yields were found to be closely related to fertile tiller number and also vegetative tiller number indicating the importance of pre-anthesis growth in determining yield. Nitrogen applied in the autumn gave cosmetic benefits in terms of greening and vegetative tiller production but the beneficial effects declined as the season progressed and only occasionally was fertile tiller number increased and on only two occasions out of a possible 42 was yield increased by autumn applied nitrogen.