Kerr C. Walker

Antifungal Activities of Four Fatty Acids against Plant Pathogenic Fungi

The effect of the fatty acids linolenic acid, linoleic acid, erucic acid and oleic acid on the growth of the plant pathogenic fungi Rhizoctonia solani, Pythium ultimum, Pyrenophora avenae and Crinipellis perniciosa were examined in in vitro studies. Linolenic and linoleic acids exhibited activity against all of the fungi. However, whereas linolenic acid reduced mycelial growth of R. solani and C. perniciosa at 100μM, the concentration had to be increased to 1000 μM before any effect on mycelial growth of P. ultimum and P. avenae was observed. Linoleic acid only reduced mycelial growth of R. solani, P. ultimum and P. avenae at 1000 μM, but led to a significant reduction in growth of C. perniciosa at 100 μM. In contrast, oleic acid had no significant effect on growth of R. solani or P. avenae, but gave significant reductions in mycelial growth of P. ultimum at 100μM and reduced growth of C. perniciosa significantly at 1000 μM. All of the fatty acids reduced biomass production by all of the fungi significantly in liquid culture when added to the media at 100 μM. Erucic acid had no effect on fungal growth at any concentration examined. The antifungal activities exhibited by linolenic, linoleic and oleic acids may be useful in the search for alternative approaches to controlling important plant pathogens, such as those examined in this study.

Persistence of seeds from crops of conventional and herbicide tolerant oilseed rape (Brassica napus)

A series of rotation experiments at five sites over four years has explored the environmental and agronomic implications of growing herbicide tolerant oilseed rape and sugar beet. This paper reports on the population dynamics of volunteer rape (Brassica napus). The experiments compared four winter oilseed rape (WOSR) cultivars: a conventional cultivar (Apex) and three developmental cultivars either genetically modified (GM) to be tolerant to glyphosate or glufosinate, or conventionally bred to be tolerant to herbicides of the imidazolinone group. Seed losses at harvest averaged 3575 seeds m−2 but ranged from less than 2000 up to more than 10 000 seeds m−2. There was a rapid decline in seed numbers during the first few months after harvest, resulting in a mean loss of seeds of 60%. In subsequent seasons, the seedbank declined much more slowly at four of the five sites (ca 20% per year) and the models predicted 95% seed loss after approximately 9 years. Seed decline was much faster at the fifth site. There were no clear differences between the four cultivars in either the numbers of seeds shed at harvest or in their subsequent persistence. The importance of the persistence of GM rape seeds, in the context of the coexistence of GM and non-GM crops and the role of good management practices that minimize seed persistence, are discussed.

The Atmospheric Sulphur Cycle

Emission, transmission and deposition of natural and anthropogenic air-borne S species are described with regard to their relevance to agriculture. Diurnal, annual and spatial patterns of emissions, concentrations and depositions are dealt with in detail. Trends of measured concentrations and depositions are presented. In Europe, the decrease of SO2 emissions has led to a considerable reduction in S deposition both from gaseous SO2 and particulate SO4 and SO3. All other S species are irrelevant for agricultural S balances. For agriculture, future depositions of sulphate S will be in the range of 5 to 10 kg ha−1 a−1. Depositions of gaseous SO2 will be in the same order of magnitude. As a considerable fraction of all S species is deposited outside the vegetation period, the future total plant available S deposition will be less than 10 kg ha−1 a−1 S.

Energy analysis of rape methyl ester (RME) production from winter oilseed rape

Abstract Energy ratios were calculated for production of the rapeseed-oil-based diesel substitute rape methyl ester (RME) from winter oilseed rape. The energy ratio of a biofuel can be defined as the ratio of the non-renewable energy used in its production to the energy value of the fuel and any utilised by-products, i.e. energy input:energy output. For each energy input and output, a range of energy values was calculated to account for different soil and weather conditions and variation in yield. In addition, the range of energy inputs calculated accounted for variation in published estimates of the amount of energy required for various processes. The range of inputs and outputs included values calculated for worst-case (i.e. lowest seed yield, highest pesticide applications, etc.) and best-case scenarios, and two intermediate values, which represented inputs and outputs expected under typical conditions in Scotland. From this data, energy ratios were calculated for rape methyl ester production under best-case, worst-case and intermediate scenarios, with and without the inclusion of by-products. The results indicated that RME production is sustainable under all but the worst conditions. Utilisation of rapemeal greatly improved the energy ratio, but there remained a net loss in energy under the worst-case scenario. Glycerol utilisation had relatively little effect on the energy ratio, while the use of straw resulted in a net energy gain from the production of RME under all scenarios.

Economics of starch production in the UK

Abstract To assess the potential for increased utilisation of UK-grown crops by the industrial starch industry, three starch processing options were considered. Starch production from: home-grown potatoes, home-grown wheat and imported maize. Wheat starch processing margins were found to be similar to, but slightly more attractive than, maize starch processing margins. Both wheat and maize margins were significantly more attractive than potato starch margins. Productions refunds paid to industrial users of wheat starch are equal to maize refunds despite a lower European Union wheat procurement price, giving a small advantage to wheat starch. A review of EU starch policy indicates the UK is unlikely to be awarded a potato starch quota due to the absence of any potato starch manufacturing tradition, and the desire of the European Commission to restrict expenditure within the potato starch regime. These quotas allow the payment of fixed premiums to potato starch manufacturers. Without them potato starch manufacture is likely to be uneconomic, discouraging any development of a UK potato starch manufacturing industry. Development of wheat starch processing technology would appear to be economically attractive as well as beneficial, both in terms of import substitution and improving options for set-aside land use. The economics of wheat starch production was calculated for a 100 000 t per annum wheat starch plant. Margins were found to be highly dependant upon sale values of the co-product wheat gluten. Any increase in milling wheat imports within GATT agreements may reduce gluten demand, forcing prices down. Maize starch by-products are sold principally into the lower value animal feed markets and therefore, by-products prices, although important, have much less impact on processing margins than in wheat starch manufacture.

Economics of bioethanol production from wheat in the UK

The cost of bioethanol production from wheat was found to be very sensitive to the price of wheat. When wheat is purchased at a typical current UK price of £115/tonne, the net cost of ethanol was calculated to be 38.3p per litre, but growing wheat on set aside at £45/tonne could result in a net ethanol cost of 21p/litre.

Adaptation potential of the novel oilseed crop, Honesty (Lunaria annua L.), to the Scottish climate

Abstract This paper reports on the adaptation potential of the biennial novel crop, Honesty ( Lunaria annua L.), to the Scottish climate. L. annua is being developed as a crop because of interest, by the oleochemical industry, in fatty acids contained within its seed, notably erucic and nervonic acids. Optimum sowing rate of the seed in these trials was approximately 15 kg ha −1 in rows spaced 0.5 m apart giving a spring plant population of approximately 20 plants m −2 . Crops gave best yields when sown around mid May to mid June. A sowing date after mid July is unlikely to produce a harvestable crop. It should be possible to achieve yields approaching 2 t ha −1 in a commercial situation in Scotland, with this figure comparable to yields attained in trials in Southern England and the Netherlands. However, large seasonal variations in yield may be observed, as was the case here. A fatty acid content approaching 30% of the seed dry weight should be possible, with around 23% of this being oleic acid, 46% erucic acid and 20% nervonic acid. A major hurdle to commercialisation of L. annua is its biennial nature, although annual cultivars are being developed.

Industrial markets for UK-grown starch

Starch is an important ingredient in a wide range of foods. It is used as a thickener, to adjust texture, to improve appearance or to act as a filler. The starch industry also supplies a diverse range of non-food industries with starch and starch derivatives. These markets account for almost half of the total production of the European starch Industry, but only 25% of the total UK starch supply. Of the 216 221 † of starch used for Industrial markets in the UK, 30% is imported potato starch, 57% is maize starch processed in the UK from imported maize, and only 13% is wheat starch, which may be both grown and processed in the UK. This article surveys some of the industrial markets for starch, highlighting recent changes which have occurred and pinpointing areas of potential development which may increase non-food use of UK-grown starch in the future. This article is based on the findings of a LINK project which was funded under the Crops for Industrial Use Programme by the BBSRC, EPSRC, SOAFD, HGCA and PMB.

Industrial Markets for UK-Grown Cereal Starch

Starch is an important ingredient in a wide range of foods. It is used as a thickener, to adjust texture, to improve appearance or to act as a fiiller. The starch industry also supplies a diverse range of non-food markets with starch and starch derivatives. These markets account for approximately 37% of the output of the European starch industry and 24% of the total UK starch supply, but starch crops do not represent a signifiicant proportion of industrial cropping in the UK.