摘要:

AbstractThe influence of seed quality on seedling growth of white clover cv Makibashiro plants was examined in a controlled environment. The average dry matter (DM) yield of 70‐day‐old seedlings from a poor‐quality seed lot was significantly less than that from a high‐quality seed lot. In both seed lots, a linear relationship between the DM yield and time from sowing was observed. The slope of regression of DM yield against time from sowing for the poor‐quality seed lot was less than the equivalent slope of the high‐quality seed lot, suggesting that possible avenues for increased DM accumulation in a high‐quality seed lot are somewhat indirect (time of emergence, uniform emergence etc.); a direct effect of seed quality on the photosynthetic ability of plant tissue seems less likely to occur. The root: shoot ratios declined in both groups of plants with increasing age. Seedlings from the high‐quality seed lot reached a stable root:shoot ratio (equilibrium state) much earlier than those from the poor quality seed lot. The seed quality had no influence on the proportion of DM partitioned to various organs. The results of this study are discussed in relation to fiel

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02301.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of two periods of rest from grazing by sheep (either April‐May or May‐June) on the composition of swards of both an early‐flowering (Aurora) and a late‐flowering (Melle) perennial ryegrass variety grown with cither a small‐leaved (Kent) or a medium‐leaved (Milkanova) white clover variety are described. Compared with a continuously stocked treatment, the early rest period did not affect the mass of clover in the swards (expressed as a proportion of the total) but resulted in a subsequent decrease in its population density. The late rest period doubled clover mass in the swards at the time of cutting but did not affect the subsequent population density of clover. The magnitude of the change in mass during the late rest period depended on ryegrass variety, but not on clover variety. The adverse effect of the early rest period on the subsequent population density of clover was associated with the degree of shading experienced by clover laminae at the end of the rest period. Temperature may also have had an effect here as mean temperatures were cooler during the early rest period than during the late rest period. It is concluded that the effects of the two rest periods on the clover content of the swards were primarily due to timing, and less to inherent differences between ryegras

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02302.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSimulated swards of reed canary grass (Phalaris arundinacea L) and ryegrass received applications of separated cow slurry liquor in winter, at rates up to the equivalent of 500 m3ha−1. Subsequent measurement of oxidized nitrogen in the soil under the different species indicated that lower levels of soluble forms of nitrogen were found under the reed canary grass than were under the ryegrass sward. At the first harvest after liquor application, the dry weight yield of reed canary grass responded positively to increasing applications of slurry liquor, but the ryegrass sward appeared to be damaged by very high rates of application. At later harvests, yields of the two species were similar, but over the season, apparent recovery of the nitrogen applied to the swards was greater in the reed canary grass than in ryegrass, suggesting that this species could be of value in the control of losses of nutrients from livestock waste

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02303.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe use of freshly cultured lactic acid bacteria in comparison with conventional freeze‐dried preparations as inoculants for grass silage was examined. Perennial ryegrass was ensiled in laboratory silos, either untreated or treated with formic acid, or a commercial freeze‐dried strain ofLactobacillus plantarum, or a fresh culture of the same strain ofL. plantarum, or fresh cultures ofPediococcus pentosaceous, orLactococcus lactisalone or in combination withL. plantarum.All inoculants were applied at a rate of 106colony‐forming units g−1fresh matter, with the mixtures containing a 1:l ratio of each species. Herbage treated with freshly cultured inoculants exhibited shorter lag times, in relation to the initiation of pH decline, than those associated with untreated or freeze‐dried inoculant‐treated herbages. Treatment of herbage with inoculants containingL. plantarumincreased the initial speed of pH decline. In comparison with silages made with freeze‐driedL. plantarum, in measurements made during the initial 14 d of ensilage, those inoculated with fresh cultures bad significantly (P<0·05) higher lactic acid concentrations and significantly (P·0.05) lower pH values. BothP. pentosaceousandL. lactisinitiated a rapid fermentation, but compared toL. plantarumalone, or mixtures ofL. plantarumwithP. pentosaceousorL. lactis, these cultures demonstrated intermediate rates of lactic acid production and pH decline. All mature (105 d) silages were of good quality with pH values of four or less, low ammonia‐N concentrations (<100gkg−1total N) and no detectable levels of clostridia or butyric acid. Results suggested that the main advantage of freshly cultured inoculants over their freeze‐dried counterparts may lie in their metabolic state

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02304.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractExperiments were earned out on seven UK sites during 1985–1988 to evaluate the importance of negative effects (smoethering and scorch) of winter and spring‐applied cattle slurry on grass yield, assessed at the time of early grazing or first‐cut silage. Slurry application has both positive and negative effects on herbage growth. Positive effects, usually associated with herbage yield increases, derive from the nutrient value of the slurry. Negative effects, often resulting in herbage yield decreases, are caused by smothering and/or scorch. The net effect on herbage depends on the balance between these positive and negative effects. These experiments were designed to isolate the negative effects of slurry whilst attempting to minimize the positive effects. Yield reductions of up to 20% for early grazing and 5% for first‐cut silage were recorded, following applications of cattle slurry in February and March. Earlier applications smaller yield reductions. The threshold for the occurrence of yield reduction was estimated at 3–4 t ha−1of slurry solids applied, at 6% solids content. In practice this would mean an application of 50–65 m3ha−1at 6% dry matter, which would supply 150–200 kg ha−1total nitrogen, based on typical slurry analyses. Within the limits of application rates tested in these experiments, yield depression tended to increase with increasing rate of slurry applied above this threshold. Although the results suggest that the effects are more likely to occur following spring applications of slurry, earlier (autumn or winter) applications would increase the risk of losses of slurry nitrogen by leaching and denitrification. These results, therefore, confirm current advice in the UK that, where possible, cattle slurry is best applied to grassland in early spring according to the fertilizer needs of the crop. High rates of application should be avoided after early March for cutting areas and, more especially

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02305.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA mathematical model of the aerobic deterioration of silage is described that includes the physical processes of gas and heat Rows, as well as an established model of microbial growth and the associated chemical changes. Yeasts and acetic acid bacteria are included in the growth model. The version of the model described relates to a cylinder of silage subject to forced aeration, a common experimental configuration. The model was very sensitive to variations in insulation thickness and yeast growth rate, and to initial pH, especially when maize was the forage. Great care is needed when selecting input data for use in the model to be sure that the physical and chemical properties are accurate. The model solution was sensitive to grid size, but with 361 cells, the maximum grid resolution that could be used on a 486 series PC, solutions were achieved with an acceptably small loss of accuracy. The model predicted the results of an experiment on silage deterioration quite accurately. However, the model also predicted that considerable spatial gradients of parameters, such as temperature, pH, and lactic acid, would occur. This indicates the need for care when taking samples or making temperature measurements in deterioration experiments. The model is potentially a useful tool in predicting the optimal time and position to take samples for analysis in a time‐course experimen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02306.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA field experiment was conducted to assess the effect of autumn defoliation treatments on inflorescence production, potential seed yield and yield components of white clover cv Makibashiro. Between 10 July and 10 October 1992, white clover swards were subjected to one of three treatments: monthly cutting to 3–4 cm (4DEF), cutting to 3–4 cm on 10 August and 10 October (2DEF), and no cutting (control). The total numbers of inflorescences and the proportion of inflorescences in different development categories were counted throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. There were consistent significant differences in inflorescence density between treatments. Plots which received the 2DEF treatment produced significantly more inflorescences than did the no‐defoliation (control) and 4DEF‐treatment plots. In this particular year the optimum harvest date (date at which the proportion of ripe inflorescences and potential seed yield was highest) was 26 July, approximately 30 d after peak flowering. Defoliation treatments had no effect on optimum harvest date. However, treatments differed in potential seed yield and ripe inflorescences on this date. The 2DEF treatment gave the highest potential seed yield because there were significantly more ripe inflorescences than either the contol or 4DEF plots. Control plots produced inflorescences with more florets than the other two defoliation treatments, but the differences were not always significant. Seed number per pod was higher in inflorescences obtained from previously defoliated plots than from control plots. The 1000‐seed weight was significantly lower in inflorescences developed in 4DEF plots than those developed in 2DEF and control plots. The results are discussed in relation to the management of white clover seed crops and the importance of canopy structure and light intensity for seed p

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02307.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractFour varieties of perennial ryegrass (Lolium perenneL.), (Ba11316, Merlinda, Morgana and Talbot), with similar ear emergence dates but differing in seasonal yield distribution were compared over two harvest years (1992 and 1993) in a small plot trial employing six levels of fertilizer N (100 to 600kg Nha−1year−1applied monthly as split dressings). In each year, a conservation cut in May was followed by five further harvests at monthly intervals. Herbage samples from each of the twelve harvests were separated into leaf lamina and other tissues, and the yield of leaf lamina calculated. The percentage of flowering tillers was determined in May and July of each year, Ba11316 produced significantly more dry matter (DM) than the other three varieties at six of the twelve harvests, but its total DM yield over all twelve harvests was 5% less than Merlinda and 3% less than Morgana, owing to lower yields of reproductive growth in May of both years. Varieties also varied in mean leaf content of the herbage over all harvests, Ba11316 being 69 g kg−1higher than that of Merlinda. Differences among the varieties in leaf content were primarily because of difference in proportion of flowering tillers, Ba 11316 having a lower proportion of flowering tillers than the other three varieties. However, the mean leaf content of the tetraploid Merlinda was significantly lower than that of Morgana although these two varieties had a similar mean percentage of flowering tillers. Despite its lower total DM yield, Bal 1316 produced 16% and 14% more leaf over the two harvest years than Merlinda and Morgana respectively. Total leaf yield of Talbot was significantly higher than that of Merlinda and Morgana, although Talbot had been developed twelve years earlier than the other two vari

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02308.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA perennial ryegrass (Lolium perenne)‐white clover (Trifollum repens) sward, that had been grazed for over 2 years, was cut at 1‐, 2‐, 3‐ or 6‐week intervals from 18 April to 28 November 1986. The effects of two rates of N application in spring, 0 and 66kg Nha−1, were compared. Clover growth was studied in three six‐week periods that began on 18 April, 18 July and 17 October respectively. Increasing the interval between cuts increased the yield of herbage without reducing the proportion of clover in the harvested herbage, but the combination of applied N and the six‐week interval was harmful to clover production. Increasing the interval between cuts tended to increase the proportion of resources allocated to stolons rather than to leaves, and to increase the weight of new dry matter (DM) per growing point rather than per m2. In the third period of the study, when the ten youngest internodes per stolon were examined separately, all ten ages of internode were found to have been affected by the cutting management. This was indicated by the positive effect of the length of the interval between cuts on the weights of N, P and K per intemode. The concentrations of N, P and K were highest in the youngest intemodes. The application of N reduced the proportion of new DM allocated to stolen rather than to leaf and it reduced the number of clover growin

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02309.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTen commercial varieties of winter wheat were sampled at different stages of growth, and dry mailer (DM) yields and potential nutritional quality, as determined by modified acid detergent fibre concentration (MADF), were measured. Maximum yields for the different varieties were spread over a four‐week period, when the DM content was above 350 g kg−1. When the varieties were harvested for conservation as either fermented (DM 380 g kg−1) or alkaline (DM 580 g kg−1) whole crop, the mean MADF concentration was similar at both harvests, with large differences recorded between varieties. At both harvests the quality of the crops was sharply increased by raising the cutting height from 10 to 40 cm above groun

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02310.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY