摘要:

AbstractEight maize (Zea maysL) hybrids were grown under five N levels with or without the nitrification inhibitor, nitrapyrin (2‐chloro‐[6‐trichloro‐methyl] pyridine), to evaluate N interactions relative to yield performance, N use efficiency, grain protein concentration, and kernel texture. Results indicate that maize hybrids can be grouped into three categories based on grain yield: (1) low N‐responsive types which reach their maximum yield with 134 kg ha−1of applied N; (2) intermediate types that respond to moderate N levels (134 to 201 kg N ha−1); and (3) high N‐responsive types that respond to higher levels of N (201 kg N ha−1). High N‐responsive types, in general, increased yield with nitrapyrin treatment at all levels of N. Crop N utilisation efficiency for high N‐responsive hybrids decreased, but was static for low N‐responsive hybrids as N fertiliser increased. In general, as the grain yield of a hybrid increased in response to N, the concentration of protein in the kernel increased; although grain yields and protein concentration are negatively correlated among hybrids. Increased kernel translucence, an indicator of kernel hardness induced by N fertiliser, correlated highly positive with zein proteins. Isoelectric focusing analysis showed that increases in zein were primarily due to a quantitative increase in α‐ and γ‐zein polypeptides. This study indicates that hybrids are different in their N requirements for maximum yield. Low N conditions not only restrict grain yield but also a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580102

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe possible role of allyl cyanide (ACN), the nitrile breakdown product of prop‐2‐enyl glucosinolate, in reducing the voluntary food intake (VFI) of a dried grass pellet diet in sheep was examined in a ruminal infusion experiment. Voluntary food intake of Scottish Blackface wether lambs, infused intraruminally with allyl cyanide (0 mmol day−1, C; 4.8 mmol day−1L; 9.6 mmol day−1, H) for 9 weeks was significantly depressed (P<0.05) on H and L treatments compared with the C treatment. Clinical indicators of liver function (plasma gamma glutamyl transpeptidase (GGTP) activity) and kidney function (plasma urea and creatinc concentrations) indicated minor liver damage but no effects on renal function. Plasma GGTP activity was significantly (P<0.05) higher in the H than in the C group. Liver cytochrome oxidase activity at the end of the infusion period was significantly lower (P<0.05) in the H than in the C group indicating effects on cellular respiration. In general, sheep showed considerable tolerance to administration of ACN in comparison with previously demonstrated toxicity in mon

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580103

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPrevious studies have shown that sheep are relatively tolerant to the prop‐2‐enyl glucosinolate breakdown product, allyl cyanide (ACN). In order to examine the extent to which this is due to degradation of the toxin in the rumen, the in‐vitro stability of ACN in sheep rumen fluid was determined. Gas chromatography of the volatiles in rumen fluid sequentially sampled following addition of ACN revealed a steady reduction in ACN concentration in the rumen fluid of cabbage‐fed sheep (1.0 μmol ml−1to 0.36 μmol ml−1in 100 min) but not in that from sheep fed dried grass (1.0 μmol ml−1unchanged after 160 min). In a further experiment the time taken to develop an adapted rumen microbial population was determined by switching sheep abruptly from a grass to a cabbage diet and measuring the ‘ACN‐degrading potential’ of rumen fluid over 29 days. Adaptation was rapid (<6 days) and could confer tolerance to the effects of ACN to sheep consuming

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580104

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractRelationships among soluble phenolics, soluble and insoluble proanthocyanidins (PAC), lignin, N, neutral‐detergent fibre (NDF), and in‐vitro degradability of protein and NDF were determined in 72 West African fodder trees and shrubs. Species were collected in the semi‐arid (Niger), sub‐humid (Nigeria) and humid/sub‐humid (Benin) zones. Variation among species in chemical composition and in‐vitro degradability of protein and NDF was large. Zones did not differ in mean content of phenolic compounds. Protein degradability was negatively correlated with soluble phenolics (r= −0.34,P<0.01) and soluble PAC (r= −0.47,P<0.001). NDF was positively correlated with soluble PAC (r= 0.44,P<0.001), insoluble PAC (r= 0.28,P<0.05) and lignin (r= 0.76,P<0.001). NDF degradability was negatively correlated with soluble PAC (r= −0.40,P<0.001) and lignin (r= −0.59,P<0.001). Chemical composition and in‐vitro degradability along with field observations can provide useful criteria for determining the nutritive va

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580105

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractGuava, a tropical fruit, is valued for its aroma and is used in many fruit products. Earlier work from this laboratory has shown that the expression of the flavour as a secondary metabolite through tissue culturein vitrois possible. In the present study an attempt has been made to maximise the callus culture growth through optimisation of the hormonal combinations of indole acetic acid (IAA), 2,4‐dichlorophenoxy acetic acid (2,4D) and kinetin (Kn). The effect of using fruits of different maturity was also assessed. The study of the complex interactions of the growth hormones and the identifications of the optimal hormonal levels have been carried out using appropriate design of experiments which are specially framed for such purposes. Simplex optimisation techniques were used to obtain the optimum levels of these hormones for highest relative growth in the experimental region. The results indicate that callus culturing with fruits before reaching climacteric with MS medium supplemented with 0.01 mg litre−1of IAA and 2,4D and 2.87 mg litre−1of Kn results in a high relative growth of 8.97 for the c

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580106

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractGrain samples from nine sorghum (Sorghum bicolor(L) Moench) cultivars were germinated for 16, 48, 96 and 144 h, and changes in their diastatic activity, protein, starch, soluble sugars, tannin and total phenols contents were studied. The diastatic activity increased up to 96 h of germination and decreased at 144 h. Diastatic activity showed significant variation among cultivars, which ranged from 10.0 to 88.3 units at 48 h and from 20.0 to 150.4 units at 96 h germination. In general, starch content decreased while soluble sugars increased during germination. Variation in protein content during germination was appreciable among the cultivars.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580107

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAfter‐cooking blackening (ACB) in potato cultivars results from the formation of complex compounds of chlorogenic acid and iron ions. At present the estimation of chlorogenic acid content represents the most reliable method for predicting the extent of ACB in material in a potato breeding programme to allow subsequent selection. A number of methods for determining chlorogenic acid levels, including high performance liquid chromatography, sodium nitrite and other colorimetric and chromatographic assays, are evaluated. A rapid screening method for the direct determination of chlorogenic acid levels is described, and its application within a breeding programme and the results obtained from a number of cultivars are discusse

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580108

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe steam distillation of tea tree (Melaleuca alternifoliaCheel) oil was investigated in a small batch still to ascertain the effect of operating variables on the yield, composition and rate of recovery of oil. Provided suitable distillation times (2–3 h) were used, the oil yield and composition did not vary with steam rate or pretreatment of the leaves by maceration. However, the rates of recovery of individual oil components were markedly affected.The results demonstrate that the oil components can be divided into two main groups according to their distillation behaviour. Oxygenated components, particularly terpinen‐4‐ol and 1,8‐cineole, are recovered the most rapidly, despite their high boiling points relative to other components. Their rates of recovery are increased with increasing steam rate, but are insensitive to leaf maceration. A second group of components, characterised by either a hydrophobic structure (the monoterpenes) or a larger molecular size (sesquiterpenes), exhibited the opposite behaviour. The rates of recovery of these components were unaffected by steam rate and improved by leaf maceration. It is hypothesised that the rate‐limiting processes for oxygenated and hydrophobic components are different. For the former, recovery is mass‐transfer film controlled, whereas the latter are diffusion controlled. This understanding provides the basis for manipulating oil quality by process

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580109

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThree trypsin inhibitors of 20, 12 and 7 kDa were isolated in pure form from seeds of the vineClitoria ternateaL of the tribe Glycineae of the Papilionoideae. The 20‐kDa inhibitor is a one‐chain molecule with arginine in the reactive site. The 12‐kDa one is also a one‐chain molecule and has lysine in the reactive site. It is also an inhibitor of chymotrypsin. They were tentatively assigned to the Kunitz and Bowman‐Birk families, respectively. The small molecular weight inhibitor (7 kDa) also has an arginine in the reactive site and is probably of the Bowman

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580110

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe changes in the biogenic amines tryptamine, 2‐phenylethylamine, putrescine, cadaverine, histamine and tyramine of straw mushroomVolvariella volvacea(Bull, ex Fr) Sing produced by heat treatment and during storage at different temperatures were studied. About 80% of the original content of these amines was lost during cooking. Commercial canned straw mushroom contained low amounts of amines. The amine contents of straw mushroom increased during storage at 4°C, with particularly notable increases in the concentrations of 2‐phenylethylamine and tyramine after 5 days' storage. However, the levels of all amines increased more markedly during storage at 25°C, and the increases in the putrescine and cadaverine concentrations were much greater than those reached a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740580111

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY