摘要
Crop nutrition has a significant effect on disease incidence, resistance or tolerance of various crops. There is currently a lack of reliable recent UK-based research about the effect of copper, zinc and boron on disease incidence, green leaf area （GLA）, green leaf retention （GLR） and grain yield of winter wheat, spring wheat and spring barley. Data analysis showed that these trace elements had positive effects on GLR. These positive effects may have been due to the role of copper, zinc and boron in the production of defence related compounds （phenolics and lignin）, which may have reduced the disease incidence resulting in prolonged GLR. Grain yield was significantly enhanced by the application of these trace elements on the crop grown on high pH calcareous soil, which can be partly attributed to enhanced GLR. Also trace elements have a positive role in reproductive growth, flowering and male fertility. On average, zinc was found to be the most consistent trace element in terms of enhancing GLR and grain yield. Across all trials, it was noted that for every 10% increase in GLA from trace elements, grain yields increased by 4.2% in 2012-2013, by 4.4% in 2013-2014 in winter wheat and by 3.9% in spring wheat in 2014. These are remarkably consistent and indicate that increasing GLA by 10% by early dough stage was associated with a yield improvement of about 4%. These trace elements also had a positive effect on grain protein content （GPC）. This research concluded that the trace elements had positive effects in enhancing GLA and yield. It can be speculated that with the use of these trace elements, there may be more scope for using less robust or reduced rates of fungicides to control foliar diseases, which may help to maximize farm profits.
