摘要:

AbstractThe proportion of the world's population that cannot get enough food to eat is increasing. Research has led to methods of increasing yields in ‘good’ soils with heavy inputs of fertilisers and other agrochemicals. But millions of people have to rely on food grown with few inputs on soils that are difficult to manage and present severe nutritional problems. There is a pressing need to devise sustainable systems of production that increase yields for these people. The problems that need to be overcome and the opportunities for advance are examined. Innovative agronomic practices are being developed that show promise of success. Quantitative models for soil and plant processes have also been developed and should be applied, to a greater extent than at present, in assessing possible practices in a given area, and in adapting practices to suit conditions. In addition there are a range of new techniques for measuring soil conditions and plant characteristics which should greatly facilitate progress.New methods of supplying crops with nutrients and water have led to spectacular improvements in the production of many horticultural crops in the Western world. Improvements in quality and the introduction of new products have been especially notable. They have enriched the lives of the consumer and created wealth for the producer.Pollution of the environment occurs almost everywhere. It has contributed to the economic decline of some of the earliest industrial areas of the world. Methods of overcoming the chemical constraints to plant growth on polluted and disturbed soils have been devised and have played a major part in improving the appearance of some of these former industrial areas and enabling them to attract modern industries and to enjoy new prosperity. Forest decline brought about by atmospheric pollution is becoming very serious in Western Europe and the USA. So far the only practical remedy involves the application of selected nutrients chosen on the basis of site characterist

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480402

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA survey of aflatoxins in acid‐treated grain and milk from farms using such grain was conducted in Sweden during 1986. Aflatoxins occurred most frequently (40%) in grain treated with a new formula of diluted (700 g litre−1) aqueous formic acid, but also in 31% of the samples of grain treated with 850 g litre−1aqueous formic acid. The lowest incidence was found in grain treated with propionic acid, where aflatoxins were found in only one sample (3%). Aspergillus flavus/A parasiticus occurred in the same manner, but were more frequent than the aflatoxins. When cultivated on aflatoxin‐producing agar, positive reactions were more common (56%) among strains originating from grain treated with formic acid than among strains originating from grain treated with propionic acid (4%). Aflatoxin M1in concentrations over 50 ng kg−1was mainly found in milk from farms using formic acid, and in most of these cases aflatoxins were also detected in the grain samples. In some cases, milk from a single farm was contaminated enough to generate consumption milk from the dairy with aflatoxin M1concentrations above or close to 50 ng kg−1.The risk of aflatoxin formation after inadequate treatment of grain with formic acid is very high and is considerably lower with propionic acid. Formic acid has now been prohibited for use as a preservative of high moisture grai

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480403

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSweet potatoes (Ipomea batatasL (Lam) cv LO 323) were treated with naphthaleneacetic acid, and during storage at 25°C per cent sprouting and per cent weight loss were measured. Naphthaleneacetic acid was applied either under reduced pressure as a 1 g litre−1solution containing wetting agent or as a dust of 1, 10 or 100 mg per gram of talc. Application of naphthaleneacetic acid by either method reduced sprouting by more than 50% during a storage period of at least 40 days, with the exception of the 1 mg naphthaleneacetic acid per gram of talc which reduced sprouting by 29%. Treatments that significantly reduced sprouting increased water loss. A mechanism for the control of sprouting is propos

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480404

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA new15N technique (termed the negative discard method) for measuring recovery of foliar‐applied N by crops in the field is described.15N‐labelled fertiliser solution is sprayed on to a small area of crop, using a hand sprayer, while the surrounding area is sprayed with unlabelled N at the same rate. An area considerably larger than that given15N is harvested with a small‐plot combine‐harvester, and crop recovery of foliar‐applied N is calculated from the15N enrichment of the resulting sample containing a mixture of labelled and unlabelled material.The technique was used to measure recovery of N from15N‐labelled urea solution sprayed on to winter wheat (Triticum aestivumL cv Avalon) at six different times from growth stage 39 (3 weeks before anthesis) to growth stage 73 (2 weeks after anthesis). Each treatment of 40 kg N ha−1was divided into two equal portions, the second being applied 1–2 days after the first, to minimise the risk of leaf damage. The crop had earlier received 210 kg N ha−1, as ‘Nitro‐Chalk’, in spring (50 kg ha−1at growth stage 22 and 160 kg ha−1at growth stage 31) which was more than sufficient to achieve maximum grain yield. At harvest, 70% of the foliar‐applied N given at anthesis (growth stage 65) was recovered in the above‐ground crop, including 64 % in grain. The proportion of labelled N recovered in the grain (92% of that in the above‐ground crop) was slightly greater than with soil‐applied N given earlier in the growing season. Recovery of foliar‐applied N was slightly less for the earliest (growth stage 39) and latest (growth stage 73) times of spraying: 64% and 58% in above‐ground crop, and 56% and 54% in grain, respectively. All of the foliar applications of 40 kg N ha−1increased %N in grain to the same extent as an additio

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480405

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo low molecular weight durum wheat (Triticum durumDesf) glutenins, DSG‐1 and DSG‐2 (durum‐wheat sulphur‐rich glutenin fractions) were isolated from two cultivars, Mondur of good technological quality and Kidur of poor technological quality. The glutenin fraction, composed mostly of DSG protein, was extracted using a low concentration of NA‐tetradecanoate and then fractionted by by using molecular sieve chromatography (Bio‐Gel P 30). The amino acid compositions and the N‐terminal sequences of the pure DSG proteins were determined, and their hydrophobic characteristics, calculated on the basis of these data, showed that DSG‐2 is more hydrophobic than DSG‐1. The amino acid compositions of DSG‐1 and DSG‐2 were different. The N‐terminal amino acids of DSG‐1 and DSG‐2 were also different but were identical for each of the two cultivars. In the case of DSG‐1, in addition to the main chain a minor chain was found in which the first three amino acids of the main chain were missing. The minor chain represented about 30% int he DSG‐1 of

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480406

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect has been studied of a range of concentrations of ochratoxin A on some biochemical parameters, viz chlorophyll, protein and nucleic acid concentrations during seed germination and seedling growth in mung beans (Vigna radiata (L) Wilczek, var Pusa 119). Reduction in levels of all the parameters resulted from ochratoxin A treatment, and the extent of reduction was directly influenced by the concentration of toxin applied.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480407

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractQuantitative analysis of the major γ glutamyl peptides present in cultivars of onion (Allium cepaL) bulbs representing brown, white and red varieties was achieved by ion exchange and electrophoretic separations and by quantitation involving integration of ninhydrin‐developed spots on thin layer chromatography.γ Glutamyl trans‐prop(I)enyl cysteine sulphoxide was found to be the major γ glutamyl peptide in each of the three cultivars at levels between 1.24 and 2.18 mg g−1fresh weight, followed by S‐2‐carboxypropyl glutathione (0.45‐0.60 mg g−1fresh weight) and γ glutamyl phenylalanine (0.09‐0.16 mg g−1fresh weight).Conclusive identification of each of the compounds was achieved by NMR spectroscopy and by GC‐MS of the n‐butyl, trifluoroacetyl derivatives o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480408

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractForms of oxalate inAmaranthus gangeticusL (a vegetable amaranth) grown in three sites with different soil and climatic factors were identified, and their contents were determined. On average the total oxalate content was 91 g kg−1on a dry weight basis. This is high when compared with the amounts reported to be a health hazard in other vegetables and forage crops. Two dominant fractions of oxalate in amaranth were isolated: a fraction soluble in boiling water which was predominantly in the form of potassium and magnesium oxalate, and an associated insoluble residue which was predominantly calcium oxalate.Most of the Ca in amaranth is unlikely to be available to the body. A suggestion was made that research on reducing the oxalate content of amaranth should first be directed at soluble oxalates because they can interfere with Ca availability from other food source

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480409

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThree procedures are described for the calculation of digestible or metabolisable energy values of food components making a small contribution to the diet in energy balance experiments. Each procedure is assessed for the extent to which measurement errors associated with energy balance studies are magnified when calculating these values. It is shown that one procedure used currently in the literature is subject to sonsiderable error (for example 30‐fold magnification errors for a component comprising ∼5% of the food dry weight) whereas others are very much less prone to errors of this kind. A new procedure is described which minimises the effects of experimental error. It is concluded that energy values of components contributing a small fraction of energy intake can be determined with greater accuracy by energy balance than is often considered possi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480410

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPepper (Piper nigrumL) volatile oil was extracted with supercritical fluid carbon dioxide at pressures of 8 and 10 MPa and at two different temperatures, 40°C and 60°C. The mass transfer rates are presented at different supercritical conditions of extraction, together with the fractionation effect that was observed. The volatile oil obtained was analysed for its physical constants: specific gravity, refractive index and optical rotation. The samples were fractionated by column chromatography, and both the samples and fractions were subjected to TLC, gas chromatography and sensory analysis. It was observed that pepper oil obtained with supercritical fluid carbon dioxide at 10 MPa and 60°C was superior to steam‐distilled

ISSN:0022-5142    

DOI:10.1002/jsfa.2740480411

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY