摘要:

AbstractA function is presented which closely describes photosynthetic area production and senescence for winter wheat canopies. Maximum and mean rates of foliar growth and death can be calculated, together with estimations of initial canopy area and the position and value of maximum canopy area.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350702

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractAssay conditionsin vivofor determining nitrate reductase activity (NRA) in shoot and root tissues of winter barley (Hordeum vulgareL. cv. Igri) were studied. The composition, pH and temperature of the incubation medium, and the size of leaf slice were varied. Maximum leaf NRA was obtained with 5 mm transverse slices incubated at 32oC in a medium containing 0.1Mphosphate buffer, pH 7.0, 0.02MKNO3, 30 ml litre−1propan‐1‐ol and 0.1 ml litre−1Triton X‐100. The optimum assay conditions for roots were similar to those for leaves, except that the pH was 7.5. There was negligible nitrite reductase activity in leaves incubated in

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350703

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350706

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe field pH of a silty clay loam soil affected manganese, zinc and copper concentrations in the fraction extracted by DTPA; lower pH soils had higher metal concentrations. The soil pH also affected manganese and zinc but not copper concentrations in the soil solution, and in shoots of clover grown in pots. Metal concentrations in soil fractions were not affected by soil phosphate status, but zinc and copper concentrations in clover shoots were significantly lower when plants were grown on soils of high phosphate status. Manganese and zinc levels in shoots were predicted slightly more accurately by using soil solution data than by using concentrations extracted by DTPA.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350707

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractFour methods of measuring sulphate content were tested on aqueous KH2PO4extracts from 24 soils, representing a wide range of soil types within Northern Ireland. The methods compared were (i) reduction to hydrogen sulphide (Johnson–Nishita); (ii) loss of barium from solution following barium sulphate precipitation; (iii) turbidimetric measurement of suspended barium sulphate; and (iv) measurement of residual 2‐aminoperimidine by spectrophotometry following precipitation of 2‐aminoperimidine sulphate. The barium loss method was about as precise and accurate as the hydrogen sulphide method, but did not measure the organic sulphur compounds extracted and so tended to give lower values than the hydrogen sulphide method. However, both these methods seemed to be satisfactory. The other two methods were much less precise and, on average, the turbidimetric method overestimated the amount of sul

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350708

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractCopper (I and II) and iron (II and III) ions had qualitatively similar effects on the degradation of radiolabelled 3‐indolylmethylglucosinolate. In the presence of myrosinase they increased the production of 3‐indolylacetonitrile (IAN) largely at the expense of ascorbigen (ASC). With the addition of these metal ions the ratio of IAN to the products of the alternative pathways (3,3′‐diindolylmethane, ASC and formaldehyde) decreased as the pH increased from 4 to 7. These ions also led to a small increase in the non‐enzymic producti

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350709

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractWhole meals prepared from four cultivars (Tower, ‘French’ (unknown cultivar from France), Duo and Tandem) contained sufficient progoitrin and soluble tannins to impair trimethylamine (TMA) oxidation, and thereby allow the TMA content of eggs to rise above the tainting threshold, when they were fed as protein supplements (100 g kg−1) to hens which had been bred for low TMA oxidase activity. Hulls from Tower and ‘French’ seed produced small, but detectable, effects and since the potencies of dehulled and whole meals were similar, it was established that the hulls make only a very minor contribution to the tainting potential. Although the addition of neomycin to the drinking water when the Tandem whole meal was fed appeared to diminish its effects to a certain extent, it had little value as a prophylactic measure. It was concluded that these meals could produce widespread tainting if used commercially in the UK, and that the removal from the laying hens of the genetic defect which restricts the synthesis of TMA oxidase and thereby confers susceptibility is the only effective way of eliminating th

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350710

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractTreatment of high glucosinolateBrassica napusmeals with lime, ammonia or by micronisation lowered their tainting potential by reducing their progoitrin, soluble tannin and sinapine contents. These effects were not sufficient to prevent inhibition of trimethylamine oxidation and the consequent rise in egg trimethylamine levels above the tainting threshold when the meals were fed to susceptible hens as sources of protein (100 g kg−1diets

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350711

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe glucosinolate content of 27 cultivars of commercially grown cauliflower have been determined. The levels of total glucosinolates (<120 mg 100 g−1fresh wt) were comparable with those previously reported for cabbage, but much lower than those found in Brussels sprouts. The major individual glucosinolates were identified as those possessing prop‐2‐enyl‐, 3‐methylsulphinylpropyl‐, 3‐indolylmethyl‐ and 1‐methoxy‐3‐indolylmethyl‐ side chains. Smaller amounts of but‐3‐enyl‐, 2‐hydroxybut‐3‐enyl‐, 3‐methylthiopropyl‐, 4‐methylthiobutyl‐, 2‐phenylethyl‐, pent‐4‐enyl‐, 2‐hydroxypent‐4‐enyl‐ and 5‐methylthiopentyl‐glucosinolates were also measured in some cultivars, the last three compounds not previously having been reported in cauliflower. Environmental effects, determined for the cultivars Wallaby, Coolabah, Barrier Reef and S

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350712

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractSteep moisture, malt moisture, malt yield, malt extract and extract yield were determined when barley samples in the range 5–100 g were subjected to the same malting procedure. Smaller samples took up more water during steeping, and produced malts with a higher moisture content. This led to a lower malt yield and a higher malt extract and extract yield for small samples. The malt moisture, malt extract and extract yield determinations on 5 g samples were of similar precision to those on 100 g samples, while the steep moisture and malt yield were more variable with the small sampl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350713

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY