摘要:

AbstractThe effects of plant age and variety on the level of nitrate reductase activity in three varieties ofSolanum tuberosum(Kennebec, Norchip and Early Ohio) have been studied by assaying nitrate reductase at different intervals during growth and development. Nitrate reductase appears to be localised in leaves and young stems. Negligible nitrate reductase activity was recorded in roots and tubers. The varieties differed significantly in nitrate reductase activity and the tuber protein nitrogen content paralleled the level of activity in leaves. The levels of nitrate reductase activities in leaves were also highly positively correlated with quantities of leaf inorganic nitrogen, protein and free amino acids. The activity began to decline at about 50 days after emergence, and this may be a useful indicator of when to apply nitrogen fertiliser so as to increase tuber protein content.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330502

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe effect of increased lime applications and one rate of soluble basal fertiliser on leaching losses of NH4‐N, NO3‐N, P, Ca, Mg and K from peat in containers was studied in the presence or absence ofBegonia semperflorensplants in a greenhouse pot experiment. Percentage recoveries (leached, plus extractable nutrient remaining in the peat, plus plant uptake) of mineral N and P were in the range of 60–80% while those for Ca, Mg and K ranged from 95 to 111%. Percentage leaching losses in the absence of plants were: mineral N, 75–76%; P, 59–74%; Ca, 5–7%; Mg, 14–19%; and K, 17–31%. In the presence of plants, the average decrease in the percentage loss of nutrients by leaching was: N, 9.3%; P, 4.4%; Ca, 0.5%; Mg, 0.3%; and K, 1.3% Liming tended to decrease leaching losses of NH4‐N, P, Ca and Mg but increase those of K and NO3‐N. The phosphate adsorption capacity of the peat was not measurable but significant ammonia fixation from added (NH4)2SO4was demonstrated at high pH (>6.5) concomitant with high N rates (>300 g N m−3). Effective cation‐exchange capacity (CEC) and CEC measured with unbuffered 1m NH4CI were both more than doubled with increased lime additions as the pH of the peat increased from 4.3 to 5.6. The conventional CEC measurement (NH4OAc, pH 7.0) and BaCl2‐TEA (pH 8.2) CEC both remained unaffected by the initial lime rates, and both greatly overestimated the CEC of the

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330503

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe distribution of the sulphur‐containing compounds released from cellulose xanthate after its application to soil has been investigated by laboratory experiments using35S‐labelled cellulose xanthate. It was shown that more than half of the sulphur contained in cellulose xanthate applied to soil was dispersed into the atmosphere, presumably as carbon disulphide. This release occurred rapidly during the first few hours and was virtually complete within 48 h. About 25% of the sulphur added was water soluble, and was leached through the soil by simulated rain. About 20% of the sulphur added remained attached to the soil in an insoluble form, some of it acid resistant. Ageing the cellulose xanthate for up to 14 days at 20°C before application had only minor effects on this fractionation. It is unlikely that the use of cellulose xanthate as a soil conditioner would have any appreciably harmful or unpleasant side effects, or cause damage to the environ

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330504

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA procedure for the efficient and rapid isolation of 100‐g quantities of immature endosperm has been developed using a roller device. The material produced has been used successfully for the isolation of messenger ribonucleic acid and deoxyribonucleic aci

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330505

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractBranched‐chain fatty acids (BCFA) were prepared as a concentrate from the adiposetissue lipids of barley‐fed lambs. The BCFA was included in a stock Oxoid ration at levels of 2.5–15% by weight and these diets were given to appetite to female weanling rats for up to 14 days. The influence of the diets oninter aliagrowth‐rate and fatty acid composition of tissue lipids was compared with the effect of the same stock diet with inclusions at a level of 5% by weight of 3‐methylhexadecanoic acid (3‐MHD), 4‐methylhexadecanoic acid (4‐MHD), 3,7,11,15‐tetramethylhexadecanoic (phytanic) acid andn‐hexadecanoic (palmitic) acid which, with the stock ration, served as control. Rats receiving diets containing up to 7.5% BCFA grew almost as well as did those given palmitic acid whereas the animals offered the diets containing 3‐MHD, 4‐MHD or 10% BCFA barely subsisted. Rats given 10% BCFA or phytanic acid became moribund within 3 days. BCFA accumulated to widely varying degrees in the lipids of the main internal organs. The higher proportions of these acids constituted some 40–60% of the total fatty acids of the lipids of kidney, liver and heart and were associated with diets containing 10% and 15% BCFA and 5% 3‐MHD. The lower proportions of the branched acids in the lipids of these organs were in the range 15–25% of the total fatty acids and related to diets that included 2.5% BCFA and 5% 4‐MHD. In contrast to the changes in fatty acid composition of the lipids of the main internal organs, those of the central and peripheral nervous systems were only minor, the proportions of branched acids amounting to some 3% in brain tissue and up to 14% in sciatic nerve. Clearance of branched acids from tissue lipids of the main internal organs was almost complete after the animals were returned to the basal diet for 14 days but the loss of branched acids from nerve

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330506

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractTwo isoforms of an embryonal inhibitor of serine proteases have been isolated from barley grains. Both forms strongly inhibit animal trypsins and the microbial trypsinlike protease in Pronase. Chymotrypsin is weakly inhibited, and no effect is observed on subtilisin. Grains of the high‐lysine barley mutant Risø 1508 contain about 0.35 mg inhibitor g−1grain, which is 2–4 times more than in normal barley varieties. The two inhibitor forms were isolated from Risø 1508 barley by extraction with a 5 g litre−1solution of sodium chloride acidified to pH 4.9, ammonium sulphate fractionation, anion exchange, cation exchange and gel filtration. The final preparations were homogeneous in electrophoretic analyses. The two isolated inhibitor forms are basic proteins with isoelectric points higher than pI 9 and molecular weights of about 16 000. There are only slight differences between the amino acid composition of the two forms, both being rich in cyst(e)ine, proline and basic amino acids. The properties of the two forms are very similar showing high stability to pepsin at pH 2, and to heat at 100°C, and having identical inhibitor properties against trypsin, Pronase and chymotrypsin. Both inhibitor forms have two active sites against trypsin and the trpysin‐like protease in Pronase, but apparently only one against chymotrypsin. The two purified barley inhibitor forms show immunochemical identities between themselves and with corresponding protease inhibitors from rye and w

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330507

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA high carvacrol content in essential oil is the key to the concept of the ‘oregano’ spice and is a prerequisite determining a plant's suitability for the preparation of this condiment.Origanum heracleoticumL., the main source of Greek oregano, is a chemically non‐uniform species. Within its wild population there are at least three chemo‐varieties which, although similar in their external appearance, differ in their odours. On the basis of their flavours and essential oil compositions, these varieties could be defined as marjoram, thyme and oregano‐types. The latter, which contains mainly carvacrol, is traditionally, and almost exclusively, collected for oregano spice preparation on the basis of

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330508

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractProtease inhibitory activities were screened in 12 varieties of pearl millet (Pennisetum typhoideum), 12 varieties of echinocloa (Echinocloa colona), 12 varieties of setaria (Setaria italica), 11 varieties of kodo (Paspalum scorbiculatum), 13 varieties of proso (Panicium miliaceum), 11 varieties of miliare (Panicium miliare), 29 varieties of sorghum (Sorghum bicolor) and four varieties of ragi (Eleusine coracana). Proso, miliare and kodo had no detectable inhibitory activity. Pearl millet, setaria and echinocloa millets displayed only antitryptic activity. Ragi had both antitryptic and antichymotryptic activity. Two varieties of sorghum had neither antitryptic nor antichymotryptic activity. In most other strains of sorghum, the antichymotryptic activity was more than the antitryptic activity. Pearl millet, setaria, sorghum and echinocloa extracts inhibited the proteolytic activity of both human and bovine pancreatic preparations.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330509

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn red beet (Beta vulgarisL. var.conditiva) the main degradation product of added nitrapyrin [2‐chloro‐6‐(trichloromethyl)‐pyridine] has been shown to be 2‐chloro‐6‐(dichloromethyl)‐pyridine. The distribution of these two compounds in beet was also studied. The highest content of nitrapyrin residues (dry weight) was found in the root tips and the petioles; the peel contained more than the leaf laminae or other parts of the root. The higher the nitrapyrin content, the higher was the ratio of nitrapyrin to its dechloro form. No clear linear correlation was observed between the content of nitrapyrin and its dechloro form. The amounts of nitrapyrin residues in beet treated with Ca(NO3)2were smaller than in the respective samples of beet fertilised with

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330510

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe nutritional quality of the blue‐green algaSpirulina platensishas been evaluated on the basis of its chemical and amino acid compositions and feeding trials with rats. The protein content of the alga was 58.5%, lysine 4.34 g 100 g−1protein, sulphurcontaining amino acids (methionine and cystine) 2.77 g 100 g−1protein, and nucleic acids 4%. The true protein digestibility of the alga was found to be 75.5 and its biological value (BV) 68. Supplementation of the alga with methionine (0.2%) resulted in a significant improvement in the BV and net protein utilisation (NPU), but had no effect on true digestibility (TD). TD, BV and NPU were significantly improved when the alga was supplemented with barley (50% nitrogen from both). In Chad and Mexico the alga has been used for centuries as a food. This together with its low cost of production, makes it a suitable source of high quality protein for use as a feed suppl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330511

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY