There is increasing pressure from government legislation and supermarket quality assurance schemes to reduce chemosynthetic pesticide-inputs in conventional production systems. This has resulted in the need to study potential management based approaches to develop alternative management (e.g. rotational design or crop nutrition) strategies and/or crop breeding/variety selection based approaches to reduce disease pressure or crop resistance to biotic stress. Two long-term, factorial field trials (the NSCS and the NUE-crops trials) were used to assess effects of fertiliser input types (composted manure vs mineral fertilisers), fertiliser input levels, pre-crop/rotational position, crop protection (with and without the use of chemosynthetic pesticides) and wheat genetics/variety choice on phenolic profiles in flag leaves, foliar disease severity and grain yield in winter wheat. Interactions between crop management practices and growing season were investigated using univariate and redundancy analysis approaches. Flag leaf concentrations of phenolic compounds differed between years and plant growth stages and were higher (approx 40%) in crops fertilised with organic compared to mineral fertilisers, but there were virtually no effects of crop protection on phenolic profiles. In contrast, both disease severity and crop yield were significantly affected by crop protection and fertilisation practices. The use of conventional, pesticide based crop protection resulted in lower disease severity and higher yields and mineral NPK fertilisers resulted in lower Septoria and higher mildew and stripe rust severity. Effects of precrop/rotational position and wheat genetics/variety choice, and interactions between precrop, fertilisation, crop protection and/or variety choice were also detected for phenolic profiles, disease severity and grain yield. RDA identified (a) positive associations between organic fertilisation and radiation, and concentrations of phenolic compounds in leaves, (b) positive associations between organic crop protection and relative humidity, and disease severity and (c) negative associations between concentrations of most phenolic compounds and disease severity. Results indicate that it is possible to increaseing concentrations of phenolic compounds in cereals via changes to fertilisation practices, and that this may (a) reduce disease severity and/or increase crop yield in cropping systems which omit chemosynthetic pesticides, but (b) may have no effect on disease and reduced crop yields in cereal cropping systems which use pesticides. However, varietal differences in leaf phenolic expression under organic fertilisation could not be linked to differences in disease severity and yields.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:594571 |
| Date | January 2013 |
| Creators | Almuayrifi, Mohammed Saleh B. |
| Publisher | University of Newcastle upon Tyne |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10443/2196 |
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