ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01441.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01442.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractSixty‐four samples were used to measure the accuracy ofin vitrotechniques using rumen fluid‐pepsin or pepsin‐cellulase for predicting digestibility of grasses grown with different levels of fertilizer calcium(Ca), sulphur(S), phosphorus (P) and nitrogen (N). In each case, fertilizers changedin vivodry matter digestibility (DMD) and thein vitrotechniques accurately predicted the changes inin vivoDMD caused by fertilizer Ca, P and N. Thein vitrotechniques gave biased estimates ofin vivoDMD in studies with fertilizer S. This bias was caused by a decrease in the digestive efficiency of the sheep when fed the unfertilized feed. It was concluded that biased estimates of DMD may be associated with low fertilizer levels and these cannot be eliminated by improving thein vitrotechniques and would also apply to estimates of DMD based on chemical analysis of the

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01443.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThree experiments were carried out in boxes to determine the response ofL. perenneseedlings to competition fromP. trivialisseedlings at different densities and ages and when the proportions of the two species were varied according to the replacement principle. Tiller numbers per plant were significantly reduced byP. trivialisat densities commonly found in the field. Prior establishment ofP. trivialiscaused disproportionate damage toL perennetillering and the early removal of such plants resulted in yield benefits toL. perenne.When sown together,P. trivialiswas shown to be competitive towardsL. perenneduring the first 4 weeks of establishment but during the next 4 weeks, although competition was still occurring between the two species to the detriment ofPoa, relative productivity (but not total productivity) was marginally greater in the mixture. The need for early herbicide treatment to prevent interspecific competition between graminaceous species during establishment is discussed.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01444.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA sampling procedure for estimating herbage intake by the ‘Difference’ method over short grazing periods using an electrically powered sheep‐shearing head to cut long narrow sample strips, was compared with several indirect animal techniques on single‐variety grass swards. The method provided intake estimates in good general agreement with those obtained by animal methods but discrepancies arose when used on a semi‐prostrate variety due, probably, to incomplete recovery of sampled herbage cut from post‐grazing residues.It was concluded that the method might be usefully adopted for the preliminary assessment of the intake characteristics of herbage varieties in routine evaluation programmes, provided that care is taken to ensure the efficient collection of herbage sampled post‐grazing and that a reduction in the land requirement can be achieved without undue loss of accuracy or precision. Confirmation of results should be sought using animal methods

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01445.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of level of removal of current season's shoots of heather (0,40 and 80% of the dry matter of the shoots) in the summer and autumn on the intake and diet selection by grazing Scottish Blackface wether sheep was examined in an experiment conducted over two years in which all combinations of level and season of grazing were provided. The treatment plots were grazed for 5 weeks at any one time and measurements made of intake and diet selection in weeks 2 and 5.In both the summer and autumn grazing periods level of removal in week 2 had little effect on the quality of the diet selected. In week 5, digestibility of organic matter was higher for the 40% than the 80% level of removal in the summer (0·543 vs 0·508) and particularly in the autumn (0·503 vs 0·449). Digestibility of the diet selected was higher in week 2 than in week 5 in both the summer (0·555 vs 0·525) and in the autumn (0·511 vs 0·476). Mechanisms of diet selection are discussed.In the summer grazing period only small differences existed in intake of organic matter between levels of removal but in the autumn intakes were higher at the 40% than the 80% level of removal. In a clipping experiment in which 0, 40 or 80% of the length of current season's shoots was removed in May, July and September in 3 consecutive years the nitrogen content of clippings in May and July was higher and the cell wall constituent lower at the 40% level in comparison to the 80% level of removal. Higher levels of removal at the previous clipping increased the nitrogen content of the clippings in May, July and September and reduced the cell wall constituent content in Se

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01446.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractDates of initiation of reproductive development and of ear emergence were determined for four cultivars of perennial ryegrass (Lolium perenne) representing a range in maturity from early to late in a single trial in 1977. The influence of climatic factors upon the reproductive development was investigated and it was found that, while day‐length largely influenced the dates of initiation, subsequent growth and development towards ear emergence was influenced mainly by temperature. The data indicated that cultivars may have similar requirements in terms of accumulated temperature between the physiological growth stage of initiation and the agronomically significant growth stage of ear emergence. The possibility of achieving greater accuracy in forecasting ear emergence dates by relating meteorological data to the physiological development of the individual cultivars is suggeste

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01447.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01448.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Book review in this articlePrinciples of Herbage Seed ProductionTechnical Bulletin No. 1, Welsh Plant Breeding Station. 2nd edition. Revised by E. W. Bean.Environmental Role of Nitrogen‐fixing Blue‐green Algae and Asymbiotic BacteriaEdited by U. Granhall.Ecological Bulletin No. 26, Swedish Natural, Science Research CouncilProduction Ecology of British Moors and Montane GrasslandsEdited by O. W. Heal and D. F. Perkins, assisted by W. M. Brown.Food Production SystemsCourse T273. A Technology Second Level Cou

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1979.tb01449.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY