Crop disease not only threatens global food security by reducing crop production at a time of growing demand, but also contributes to greenhouse gas (GHG) emissions by reducing efficiency of N fertiliser use and farm operations and by driving land use change. GHG emissions associated with adoption of reduced tillage, organic and integrated systems of field crop production across the UK and selected regions are compared with emissions from conventional arable farming to assess their potential for climate change mitigation. The reduced tillage system demonstrated a modest (<20%) reduction in emissions in all cases, although in practice it may not be suitable for all soils and it is likely to cause problems with control of diseases spread on crop debris. There were substantial increases in GHG emissions associated with the organic and integrated systems at national level, principally due to soil organic carbon losses from land use change. At a regional level the integrated system shows the potential to deliver significant emission reductions. These results indicate that the conventional crop production system, coupled to reduced tillage cultivation where appropriate, is generally the best for producing high yields to minimise greenhouse gas emissions and contribute to global food security, although there may be scope for use of the integrated system on a regional basis. The control of crop disease will continue to have an essential role in both maintaining productivity and decreasing GHG emissions.
The antifungal activity of volatile oil obtained from the leaves of sweet gale (Myrica gale) has been investigated. Fungi, isolated from the leaves of M. gale, were grown in liquid medium containing the oil and its effect on biomass production was gauged. The oil inhibited growth of all species of fungi to greater or lesser extent. Sesquiterpenes were more active than monoterpenes, and among the sesqui-terpenes germacrone was marginally more active than 13-elemenone. These results support the proposition that the volatile oil of M. gale has a role in resistance to fungal pathogens.
SummaryThe leaf gland volatile oils of ten sweet gale plants from a Scottish population were extracted in early summer. The results differed notably from reports of other populations in respect of the sesquiterpenes, [3-elemenone and germacrone, which were major components of the volatile oll. Three dihydrochalcones were also detected in the volatile oll. Variation within the population existed, particularly with respect to the relative importance of germacrone.Five plants were resampled in late summer and exhibited a marked reduction in 13-elemenone, a lesser reduction in germacrone and changes in the proportions of some monoterpenes.
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