摘要:

AbstractA study was made of the effects of seedbed compaction and use of fertiliser (application rate, placement, and the choice of ammonium or nitrate forms of nitrogen) on the availability of manganese to barley in light soils in East Scotland. Generally, the uptake of manganese by the plants was increased by increasing the amount of fertiliser applied and by compaction of the seedbed, although no significant increase in extractable soil manganese was detected. The increase in uptake from wheel‐tracks (where the compression had resulted in an element of fertiliser placement), compared with nonwheeled areas, was much greater than the effect due to overall plot compaction by tractor wheels in the absence of a fertiliser placement effect. Combine‐drilling of fertiliser with the seed resulted in large increases in plant uptake of manganese in non‐wheeled areas, compared with uptake where the fertiliser had been broadcast, but had no significant effect in the wheel‐tracks where growth and uptake were generally better. In some, but not all, experiments, significant reductions in pH occurred in the soil beneath the wheel‐tracks which were very closely correlated with increases in extractable manganese. Use of ammonium sulphate as nitrogen source also reduced the pH, compared with calcium nitrate, and this, too, increased extractable manganese and greatly improved plant growth. The probable cause of enhanced manganese availability was soil acidification brought about by nitrification of ammonium fertiliser and/or by H+ion secretion by roots to balance the uptake of ammonium and other cations. The uptake of manganese by the plant was further improved either through concentration of fertiliser in the root zone by placement, or by soil compaction which resulted in shallow sowing of seed and a closer active relationship between roots and broadcast fertiliser. Other possible factors involved were (a) a greater exudation by roots of compounds able to dissolve insoluble manganese, in compacted soil; (b) contact reduction processes; (c) stimulation of root growth, leading to more efficient uptake by the plant, where higher rates of fertiliser were used or where the fertiliser was concentrated in localised zones in

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340702

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractInvestigations on light soils from 1977 to 1981 revealed important effects and interactions of husbandry methods and fertiliser placement on barley growth and yield which were largely due to their effects on Mn availability to the crop. Thus combine‐drilling an acidifying fertiliser (but not a non‐acidifying fertiliser) with the seed rather than broadcasting it, was very effective in controlling Mn deficiency and increasing yield substantially on Mn deficient sites. Soil compaction was beneficial where the fertiliser was broadcast, primarily because it forced shallow sowing of seed and thus kept the seminal roots near the acidifying fertiliser. Deep sowing of seed greatly reduced yield when fertiliser was broadcast but not when fertiliser was placed near the seed. These effects and interactions explain why poor crops were frequently associated with loose seedbeds, deep sowing and broadcast fertilis

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340703

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractEight winter‐wheat experiments conducted by Rothamsted on clay soils in 1980 and 1981 formed part of an inter‐institute collaborative programme on yield variation. The tests included no N and four amounts of fertiliser N up to 200 kg ha−1, with and without spray treatments to control pests and diseases. Large grain yields—in excess of 10 t ha−1—were often obtained, mainly where losses had been limited by sprays. In Belgium, 10 experiments during the same seasons were on a wider range of soils and had spray treatments applied to all plots. Yields exceeding 10 t ha−1were obtained at one site. Graphs showing the inter‐relationship between grain‐N %, grain yield and N uptake are used to compare the recent results with those from a 20‐year study of similar data from 124 earlier Rothamsted experiments. The envelope curve delineating the range of yield and grain‐N % values from these older experiments enfolded most of the more recent data points, except those deriving from the largest yields which were associated almost entirely with grain‐N % values below the minimum recommended for British breadwheat. The largest grain‐N uptakes were 180–190 kg ha−1and 170–180 kg ha−1in the recent Rothamsted and Belgian experiments respectively, compared with 160‐170 kg in the older experiments. The linear or near‐linear relationship between grain‐N % and amounts of fertiliser N, established in the 20‐year study, was again observed in the recent Rothamsted and Belgian experiments, with about 38 kg of added N needed t

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340704

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractUsing the nitrogen balance technique, the effects ofS‐Methyl‐L‐cysteine on the protein quality of egg albumin, extracted microbial protein and Maris Bead bean as well as in amino acid mixtures has been evaluated. No sparing effect was observed for methionine or cystine under any of the experimental conditions investigated. Equally, with a minor exception, no serious deleterious effect appears to result from the feeding ofS‐Methyl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340705

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractSheep and steers were given, at a maintenance level of feeding, four diets consisting of either poor quality dried grass, good quality dried grass or separate mixtures (63:35) of each of the dried grasses and barley. Ammonia and total N concentrations in rumen liquor were significantly higher in sheep than in steers whereas total volatile fatty acid concentration was significantly lower and protein N concentration, pH and rumen fluid dilution rate did not differ significantly between species. For all rumen measurements, except total volatile fatty acid concentration, there were significant differences between diets with the dietary responses being similar in both species. Protein degrading activity in the rumen was measuredin vitrowith casein as the substrate andin situby measuring N disappearance when soyabean meal, cotton seed meal, groundnut meal, meat and bone meal, fish meal and dried grass were incubated in polyester bags in the rumen. Casein degrading activity of rumen liquor did not differ significantly between species, whereas rumen in‐situ degradation of all feedstuffs, except fish meal, was significantly higher in sheep. In both species, ruminal casein degrading activity was higher when the good quality forage was given than when the poor quality forage was given and also increased when part of each forage was replaced by barley. In contrast, rumen in‐situ degradability of feedstuffs did not differ when the two all‐forage diets were given and the inclusion of barley in the diet reduced the rate of degradation. In both species and with all diets the rumen in‐situ degradability ranking of the feedstuffs was

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340706

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340707

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractTwo new multivariate techniques for comparing two blocks of variables were tested on sensory data from cauliflower. The techniques are based on Partial Least Squares (PLS) regression on latent variables. The method of PLS2 was used for relating four different preference variables simultaneously to 11 descriptive variables by regression on common factors. The method of PLS1 was subsequently used to relate individual preference variables to the 11 descriptive variables. Two factors were in each case found to be statistically significant by cross‐validation. The first, dominating PLS2 factor was a general quality factor showing that all the descriptive variables were more or less related to all the preference variables. This quality factor agreed well with the producers quality classification of the batches upon harvesting. A second, minor factor distinguished between texture and flavour descriptor's relationships to the preferences. PLS1 regressions showed that texture preference was best predicted by texture descriptois, especially crispness, and flavour preference was best predicted by flavour descriptors, especially fruitiness. Some benefits of the PLS methods over the conventional alternatives of stepwise regression and principle component analysis are discusse

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340708

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractRice straw was chosen as a cheap carbon source for SCP production using a locally isolated fungus identified asTrichoderma harzianum. The chemical constituents of the raw material were cellulose 43%, hemicellulose 26% and relatively low lignin, 16%. The effects of chemical and physical pretreatments on the protein production, cellulase activity and cell mass ofT. harzianumhave been investigated.Pretreatment of the raw material using a combination of NaOH and high pressure steam treatment increased its microbial digestibility from 24% to 73%. Similar results were obtained by pretreatment with sodium chlorite for holocellulose formation. However, maximum yields of cell mass and protein were obtained by the first method. The organism gave 7.18 g litre−1cell mass and 2.50 g litre−1mycelial protein. Treatment with sodium chlorite increased cellulase activities but gave a lower fungal yield. When the NaOH was applied with high pressure steam, the organism produced 32.8% crude protein, a yield similar to that given by the same organism cultured on soluble carboxymethylcellul

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340709

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractDifferences in the extent of loss of pectic substances from potato (Solanum tuberosumL.) after boiling, steaming and pressure cooking were investigated. Losses were found to be significantly greater (P<0.001) after boiling than after pressure cooking or steaming. The pectic substance content (g 100 g−1dry matter) of potatoes (cv. Pentland Crown) was 2.98 for raw peeled tubers, 0.97 after boiling for 35 min, 1.22 after steaming for 35 min and 1.24 after pressure cooking at 103.4 kPa (15 psi) for 15 min. The roles of cooking time, cooking temperature and heat transfer medium are discussed. The effects of calcium sulphate (at levels typical of ‘hard’ and ‘soft’ water supplies) in the cooking water on losses of pectic substances from potato (Solanum tuberosumL.), carrot (Daucus carotaL.), and swede (Brassica napusL. var.napobrassicaPeterm.) after boiling and pressure cooking were also investigated. Water hardness did not influence losses during pressure cooking but samples boiled in hard water had decreased losses of pectic substances compared to those boiled in soft water. The increase in retention of pectic substances due to hard water was about 8 % for potatoes (cv. Pentland Dell), about 33 % for sliced carrots (cv. Berlicum, approved maintenance Perfecta) and about 23% for diced swedes (cv. Acme). The interaction of water hardness with cooking method was significant for potato (P<0.05) and swede (P<0.001) and approaching significance (P=0.055) f

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340710

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractAcid soluble proteins (bipyramidal crystalline, 76.9% protein, 15% carbohydrate) prepared by citric acid extraction and acid precipitated proteins (amorphous, 64.2% protein, 11.3% carbohydrate) prepared by alkali extraction from baby lima beans (Phaseolus lunatus) were found to behave in a similar manner under alkaline conditions (pH 8.9) of electrophoresis (absence of urea). Striking differences were observed in the behaviour of the two types of protein preparations when electrophoresis was performed under acidic conditions (pH 4.5; absence and presence of urea and a mixture of urea and 2‐mercaptoethanol) and in the presence of sodium dodecyl sulphat

ISSN:0022-5142    

DOI:10.1002/jsfa.2740340711

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY