摘要:

AbstractThe suitability of freezing a large amount of grass from a single harvest for use in a series of experiments to investigate silage fermentation and its manipulation was examined. Perennial ryegrass, harvested in late June, was ensiled in sterile polythene bags inside an anaerobic cabinet; some was also stored frozen at ‐20°C for up to nine months before ensiling in a similar manner. The course of fermentation was followed using not only conventional chemical and microbiological analyses, but also by measuring microbial metabolic activityin vitro.Freezing and thawing affected the chemical composition and the microbial populations on the grass, and there were differences in the changes occurring in thawed grass during ensilage, probably related to damage to plant cells and impaired microbial activity associated with freezing and thawing. For both the grasses and the silages made from them, it was clear that the number of microorganisms present was not a reliable guide to microbial metabolic activity. Although the fermentation of frozen‐and‐thawed grass did not simulate precisely the fermentation occurring with fresh grass, it is concluded that, when used judiciously, the ensilage of thawed grass can be a useful experimental tool, particularly in the initial screening of manipulants of fermen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02297.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractFour sets of half‐sib families of perennial ryegrass with (E+) and without (E‐) infection with the fungal endophyteAcremonium loliiwere established in spaced‐plant nurseries and trial plots in 1989 and 1990 at eight locations in France. In the nurseries, families were scored visually for six agronomic traits; in trial plots, dry matter yields or visual scores were obtained for eleven traits in the planting year and in the following two years. Significant differences between E‐and E+ families in each set were more frequent in trial plots than in nurseries, and in all cases there was a positive response toA. loliiinfection. In the nurseries, the traits showing the greatest number of significant responses to infection were spring growth (3/28 comparisons) and autumn vigour (3/26 comparisons). In trial plots, E+ families had a significantly (P<0·05) higher yield than E‐ families at three dry locations (5/7 comparisons at Clermont‐Ferrand, 3/9 at Montours, and 4/7 at Vemeuil I'Etang) in the 1989 sowings. However, in the 1990 sowings, when different families were studied, endophyte infection had no effect on yield at the driest location. Therefore it is concluded that infection of perennial ryegrass with some strains ofA. loliiseems to benefit the host in stressful conditions. However, in Europe generally, climatic conditions are not often stressful for perennial ryegrass and the chances of E+ plants being favoured by either natural or artificial selection se

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02298.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn experiment was conducted to examine the effect of the timing and severity of defoliation on the vigour of the soft rush (Juncus effusus). Three levels of defoliation (uncut, cut at half the current green stem height, and cut at ground level) were applied at each of two cutting dates (the end of June and the end of August) in a factorial design that gave nine cutting treatments. Treatments were imposed for two consecutive years and their effects on tussock size (rush herbage mass) and vigour, as determined by green stem height, peripheral green stem density, and the proportion of flowering green stems, were assessed in Year 3. Defoliation to half the current green stem height either once or twice annually had no effect on tussock mass or vigour. Defoliation to ground level reduced tussock mass and vigour but a large number of green, living stems remained on all treatments, indicating considerable potential for regeneration once the cutting treatments had ceased. There was no significant effect of number or timing of the cuts, but the results suggest that cutting rushes to ground level twice during the growing season is more effective at reducing rush vigour. Where only a single cut is possible, cutting in August after flowering is the best option.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02299.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSoft rush,Juncus efffususL., is a widespread weed of managed grasslands. In 1991, a sample‐based field survey of the weed's distribution in improved grasslands was conducted within the catchment of the River Tyne in Northern England. The land classes of the Institute of Terrestrial Ecology (ITE) environmental landscape classification system were used as sampling strata. In total, 182 I‐km grid squares were surveyed. Areas of improved grassland and levels ofJ. effususinfestation differed significantly between land classes, but there was also wide variation between grid squares within land classes. Most squares within a land class had noJ. effusus, while a proportion had large areas. Extra‐polation from the sample data suggested that an area equivalent to 24·0% of the 3000km2land surface of the catchment supported improved grassland, of which 3·5% was infested with the rush. Infestation of improved grassland was estimated to be lowest in the lowlands (2·0% of improved grassland), intermediate in the marginal uplands (3·0% of improved grassland) and greatest in the uplands (10·8% of improved grassland). Data from the Farm Business Survey, on broad patterns of utilization of improved grassland for hay, silage and livestock in lowland, marginal upland, and upland landscapes in the catchment, do not readily explain the observed variation in infestation levels, which may reflect local factors and the availability of propagules from adjacent rough gr

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1995.tb02300.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY