摘要:

AbstractTwo grassland sites, reinstated after opencast mining for coal, were used to assess the effect of cultivation on structure rehabilitation. In general, cultivation had an adverse effect over a range of porosity and aggregate stability indices. This effect tended to be more marked in macro‐ rather than micro‐aggregate stability, in the upper rather than the lower half of the tillage layer and at higher intensities of cultivation. Some tillage responses persisted after two years.Cultivation effects were partly explained by mixing of soil within the tilled layer. However, results indicated some direct physical destruction of aggregates and a large reduction in aggregate stability. Data available did not point to any clear cause of this reduction in stability. Nevertheless, there was some evidence that cultivation may have disrupted the stabilisation of aggregates by organic matter, without influencing overall organic content.Net structural responses to cultivation are a balance of adverse and beneficial effects. In replaced soils this balance is negative. For this reason, tillage should be restricted where structure rehabilitation is a prior

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550302

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractSix high protein and high lysine barley lines were derived from four crosses involving high protein andlor high lysine donors, ie Riso 1508 and SV 73608 (Hiproly×Mona5), with well adapted local strains V 5681 and V 4342. The trial was grown at the Wheat Research Institute, Faisalabad, Pakistan. The lines were chemically and nutritionally characterized and the results were compared with the parents. The biological value, net protein utilization and lysine contents were higher in all the derived lines than in their local parents, ie V 5681 and V 4342. The increased lysine levels in the lines B 82503 and B 82507 may be a consequence of the reduction of prolamin fractions with simultaneous increases in salt soluble fractions. In all the lines, lysine and nutritional quality increase were a reflection of high protein andlor high lysine parents. The line B 82503 had grain yield comparable to its local parent V 5681 but it was superior in lysine and some nutritional attributes to its high lysine donor parent Riso 1508. In some lines, lysine improvement was achieued without impairing grain yield

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550303

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThin layer chromatography resolved nine major compounds from the 60%‐methanol extractables from PI 227687 soya bean (Glycine max(L) Merrill) leaves. The flavonoids, daidzein, an unidentified flavonoid X2 (Rf0·19), glyceollins, sojagol and coumestrol exhibited antifeedant and/or antibiotic effects against the larvae of cabbage looper,Trichoplusia niHb. The results indicate that several compounds in PI 227687 soya beans contribute to its antifeedant and/or antibiotic effects againstT ni. The role of these compounds in plant resistance to insects is discuss

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550304

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractCell walls of tall fescueFestuca arundinaceaSchreb and coastal bermudagrassCynodon dactylonL Pers were treated sequentially with increasing concentrations of sodium hydroxide (0·1 M to 10 M) to release monomeric and dimeric phenolic acids. (E)‐p‐Coumaric and (E)‐ferulic acids were the major monomers released. Most of the saponifiable feruloyl groups (97% for tall fescue, 89% for coastal bermudagrass) were released with 0·1 M sodium hydroxide. Much lower proportions of saponifiable p‐coumaroyl groups (67% for tall fescue, 46% for coastal bermudagrass) were released with this treatment. The major dimers from both grasses were 4,4′‐dihydroxy‐α‐truxillic, 4,4′‐dihydroxy‐3‐methoxy‐α‐truxillic, and 4,4′‐dihydroxy‐3,3′‐dimethoxy‐α‐truxillic acids, and were mainly released with 0·1 M sodium hydroxide. Similar proportions of the monomers and dimers were released from the cell walls of each grass with the 0·1 M and 1 M sodium hydroxide sequential treatments. It is probable that most if not all of the monomers and dimers released by the sequential alkali treatments were originally ester linked to the cell walls. If it is assumed that the cell wall bound dimers are formed photochemically fromp‐coumaroyl and feruloyl groups during plant growth, it is calculated that, for the two grasses, between 12 and

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550305

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractIn 1972 an experiment was set up to investigate the long‐term effects of herbicide, irrigation and two rates of nitrochalk fertiliser application on soil fertility in a Cox's Orange Pippin apple orchard. Samples taken in 1986 showed that uncultivated soil which had been maintained bare by herbicide had much lower organic C, total N and extractable K and Mg concentrations than soil which had been maintained under grass. Extractable P concentrations were lower in soil under grass than in soil under herbicide. In the absence of grass, soil pH was slightly lower than in its presence. All these effects were much greater at depths above 7·5 cm than below.Irrigation of the grass slightly increased organic C and total N levels at 0–7·5 cm compared with unirrigated grass but had no effect on extractable P, K and Mg.Increasing the fertiliser rate from 63 to 189 kg N ha−1had no effect on organic C, total N, extractable P and K. Yet, throughout the soil profile, extractable Mg concentrations were greater at the low than at the high N fertiliser rate.In a seedling growth test on soil taken from the orchard in 1988 (and confirmed to be free from residual herbicide), apple seedlings grown in soil which had previously been under grass grew significantly better than those in soil which had been bare. These differences were ascribed to a greater rate of N mineralisation in the soil formerly under grass.The results of this trial indicate that to safeguard soil fertility it is necessary to maintain a grass cover in the orchard. In addition, fertiliser application on newly planted trees should be adjusted to take account of the presence or absence of grass in the previous soil management tr

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550306

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe content and chemical composition of soluble and insoluble dietary fibres from the brown marine algaLaminaria digitata(kombu breton) were determined. Two enzymic‐gravimetric methods were used to determine (1) the content of soluble and insoluble fibres according to a modification of the AOAC procedure, and (2) the distribution of the soluble fibres in saline buffer at 37°C and at pH 2·0 and 7·5 used to simulate the gastric and intestinal phases of digestion, respectively. The total dietary fibre contents obtained by the two methods were similar (37·3 and 40·0%) and of these 84·8–87·4% was soluble. A partitioning of soluble fibres may occur during digestion since 49·3% was recovered in saline buffer at pH 2·0 whereas 50·7% was recovered in saline buffer at pH 7·5. Solubility of dietary fibres was related to the chemistry of brown algal polysaccharides. Fucans and laminarans were essentially soluble at pH 2·0 and alginate at pH 7·5, and insoluble fibres consisted primarily of cellulose.Oil adsorption and hydration properties (uptake, retention and swelling) in water, 154 mM NaCl, and 38 mM CaCl2at 20 and 37°C of three particle sizes ofL digitatawere measured. Oil adsorption was low (0·16–0·41 g g−1) and was related to the particle size of the fibres. Hydration properties were more important with small particles except in CaCl2solution and followed the order water>NaCl>CaCl2. Water uptake and swelling were greater at 37°C than at 20°C. The overall decrease in hydration properties observed with solutions of ionic strength ∼0·15 was interpreted as reflecting the decrease in the electrostatic repulsion between charged polysaccharides. The lowest water uptake, water retention and swelling were obtained with solutions of CaCl2, and were related to the known selective afinity of alginate for calcium. Thus, L digitata is especially rich in soluble dietaryfibres, and these have physico‐chemical properties characteristic of the polysaccharides present. Water absorption and uptake and swelling can be modulated according lovarious ph

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550307

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThirteen cultivars of cowpea (Vigna unguiculata(L) Walp) were analysed for their proximate composition, amino acid, trace element and phytic acid contents. Crude protein values ranged from 206·8 to 283·8 g kg−1DM. The mean contents (g kg−1) of other major nutrients were ether extract, 18·6; ash, 38·8; total dietary fibre, 121·8 and carbohydrates, 573·4. When compared with the provisional amino acid scoring pattern of FAO, all cultivars were low in methionine and high in lysine, isoleucine, leucine and phenylalanine plus tyrosine. Values for threonine and valine were variable compared with the pattern. The range of values for the chemical score was 0·61–0·74. Phytic acid values ranged from 5·10 to 10·27 g kg−1, and the phytate: zinc molar ratios were all higher than that (15:1) above which zinc deficiency can be induced. Most of the trace elements showed wide variation in their occurrence among the cultivars. The values for zinc and iron showed less variation. The toxic elements mercury and selenium were present in varying amounts in more than half of the cultivars while tin was found in

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550308

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTwo different chemical methods, sequential extraction with alkali and sodium chlorite and treatment with 4‐methylmorpholine N‐oxide (MMNO), were applied to the extraction of non‐starch polysaccharides (NSP) from the enzymically deproteinated, water‐insoluble cell wall materials of sunflower (Helianthus annuusL) meal and palm kernel (Elaeis guineensisJacq) meal. The NSP content accounted for 550 g kg−1(sunflower meal) and 750 g kg−1(palm kernel meal) of the cell wall materials. Neither of the treatments alone was capable of solubilising more than about half of the original NSP. Combined treatment using alkali/chlorite followed by MMNO completely dissolved cell wall material from palm kernel meal, whereas a small residue (40 g kg−1of original NSP) was left in sunflower meal. Loss of NSP occurred with both methods (total NSP recovery ranging from 88% for alkali/chlorite extraction of sunflower to 64% for MMNO extraction of palm kernel). Due to differences in solubility revealed upon acidification and/or dialysis, extracts became subdivided into precipitates and soulble fractions. The sugar composition of the resulting fractions enabled a tentative identification of teh major non‐starch polysaccharides; sunflower meal was found to contain cellulose, (acidic) xylans, polyuronide‐containing fractions and xyloglucan; palm kernel meal was found to contain mannans, cellulose and xylans, with the major part of the mannans originating from the endosperm and the xylans being almost exclusively locate

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550309

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThree Indian tribal pulses,Bauhinia purpureaL,B racemosaLamk andB vahliiW and A, were analysed for pod morphology, proximate composition, seed protein fractions, amino acid composition, minerals and antinutritional factors. The seeds ofB purpureaandB vahliicontained higher contents of crude protein and crude lipid than those ofB racemosaresulting in higher energy values for these two pulses. The seeds ofB purpureawere rich in K, whereas those ofB racemosaandB vahliiwere rich in Ca and Fe. Albumins and globulins constituted the predominant fractions of the seed proteins inB purpureaandB vahliiwhereas glutelins predominated inB racemosa. In all three species the contents of the essential amino acids lysine, tyrosine and phenylalanine were fairly high; the contents of sulphur amino acids were limiting. Isoleucine and leucine were limiting only inB vahliiproteins. Levels of the antinutritional factors investigated, free phenols, tannins, L‐DOPA, and haemagglutinating and trypsin inhibitor activities were not particularly hig

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550310

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe present study examined whether differences in mineral content of the diet or faecal samples contribute to variation in analytical recovery of marker chromium from these samples. Three corn/soya bean diets containing various levels of Ca, P and Mg, and the corresponding faeces of swine fed these diets were used. Diet and faecal samples were analysed by colorimetry and atomic absorption spectrophotometry with increments of Cr added to samples either preceding or following the acid digestion procedure. Results indicated significant differences (P<0·05) in analytical recovery of Cr between diets and corresponding faeces, between individual diets and faeces, and between methods of determination. The acid digestion step leads to the lower recovery of Cr (diets,P<0·05; faeces,P<0·01) whereas no significant differences were found in post‐digestion procedure by either method of determination, indicating that marker‐chromium loss due to the acid digestion procedure was not higher than the apparent loss due to the acid analytical method. Results suggest that the analytical recovery factors should be considered when estimating faecal recovery of marker chromium or digestibility of nut

ISSN:0022-5142    

DOI:10.1002/jsfa.2740550311

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY