title / Development of grass and white clover variety testing systems to predict performance under conventional, low input and organic livestock production
/ DEFRA
project code / VS0129
Department for Environment, Food and Rural Affairs CSG 15
Research and Development
Final Project Report
(Not to be used for LINK projects)
Two hard copies of this form should be returned to:Research Policy and International Division, Final Reports Unit
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Project title / Development of grass and white clover variety testing systems to predict performance under conventional, low input and organic livestock production
DEFRA project code / VS0129
Contractor organisation and location / IGER
Aberystwyth
UK
Total DEFRA project costs / £ 44,403
Project start date / 01/07/02 / Project end date / 13/03/03
Executive summary (maximum 2 sides A4)
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CSG 15 (Rev. 6/02) 3
Projecttitle / Development of grass and white clover variety testing systems to predict performance under conventional, low input and organic livestock production
/ DEFRA
project code / VS0129
Forage grass and clover breeding helps to support a major industry that occupies more than half the agricultural land in the UK. Value for Cultivation and Use (VCU) trials play an important role in directing the efforts of forage grass and clover breeders by determining the type of varieties added to the UK National List. It is important that the VCU system is relevant to industry practices and needs and, if possible, also helps to protect the UK environment. Grass and clover seed accounts for only 1% of the seed purchased by farmers, however, and this severely limits the funds available to seed companies for testing and marketing new candidate varieties.
The VCU system for grass and clover has evolved slowly in response to scientific developments, in order to base new standards on hard evidence, but alternative methods of setting standards may be acceptable and more responsive. Recent research has identified high water-soluble carbohydrate content of grasses as an additional trait that can be used to reduce nitrogen losses to the environment. There is also scope for altering the management of VCU trials to provide better data on winter hardiness. Consultation with 275 farmers indicated that they regarded persistency as the most important characteristic when selecting herbage seed mixtures. The other traits currently given a weighting when deciding whether or not to add a candidate to the National List were also considered important by farmers. However, both conventional and organic grassland farmers considered early spring growth to be an important characteristic that currently is given no weighting in grasses and only a low weighting in white clover. Financial limitations preclude additional trials, and so any changes will require modifications to the existing procedures for trialling varieties and making decisions.
There have been considerable changes to grassland agriculture over the last 20 years and an increase in the diversity of grassland farming systems. Less chemical fertiliser is used by most grassland enterprises, and a significant proportion (ca 5-10%) have converted to organic and now rely entirely on white clover, other legumes and organic manures to provide the nitrogen to grow forage and grain crops to feed their animals. Research is required to determine if further changes to the VCU trials are necessary to take account of these recent changes in farm practice.
Recommendation 1. That Defra endeavours, where possible with the limited resources, to incorporate into VCU trials the measurement of herbage water-soluble carbohydrate concentration of all grasses (in addition to D-value).
Recommendation 2. That grass plots are managed to increase the probability of generating reliable data on winter hardiness and disease resistance.
Recommendation 3. New means of setting standards for making VCU decisions should be adopted to reduce the delay in responding to change.
Recommendation 4. That Defra commissions research to answer the following questions.
a) Will the ranking in dry matter yield and persistency of white clover varieties grown in mixture with grass, and of grass varieties grown in monoculture, be changed significantly by severely reducing fertiliser N and P application?
b) Will the ranking in the dry matter yield and persistency of clover varieties grown in mixture with grass be changed significantly by being managed organically?
c) Will the ranking in dry matter yield, persistency and digestibility of perennial ryegrass varieties be changed significantly by being grown organically in mixture with white clover?
d) Will the importance of resistance to various plant diseases and tolerance to climatic stresses be altered by low input and organic management , or by other changes in management?
CSG 15 (Rev. 6/02) 3
Projecttitle / Development of grass and white clover variety testing systems to predict performance under conventional, low input and organic livestock production
/ DEFRA
project code / VS0129
Scientific report (maximum 20 sides A4)
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CSG 15 (Rev. 6/02) 3
Projecttitle / Development of grass and white clover variety testing systems to predict performance under conventional, low input and organic livestock production
/ DEFRA
project code / VS0129
The role of Value for Cultivation and Use (VCU) trials of grasses and clovers in UK agriculture
Grassland is as important to the landscape of the UK as all the other crops together. It occupies more than half our agricultural land, excluding rough grazing (DEFRA, 2002b). Grass and clover also support a major industry, which in 2002 produced 14,488m litres of milk, 692,000 tonnes of beef and veal, and 306,000 tonnes of sheep meat, with a total value of £5,353m. If this industry is to be sustained in the face of increasing global competition, it must remain competitive while at the same time minimising its negative impacts on the local and global environment. Improving grass and clover by plant breeding provides an important means of achieving these objectives. UK National List VCU trials (together with non-statuary Recommended List Trials) have a major influence on plant breeder’s objectives and must therefore reflect growers’ needs for improved varieties. Such independently operated trials systems provide a ‘level playing field’ that encourages competition among plant breeders and facilitates the uptake of improved varieties by farmers.
VCU trials are part of the chain between a breeder producing a new variety and its use by farmers in commercial practice. Seed sales of plant varieties in the UK are regulated in three ways: plant variety rights, variety recommendation and seed certification. The Plant Varieties and Seeds Act of 1964 introduced plant breeder's rights to the UK, under the Union for the Protection of New Varieties of Plants (UPOV). This gave a financial incentive for private seed companies to invest in breeding herbage varieties for the UK. It also necessitated a system of tests for Distinctness, Uniformity and Stability (DUS), to identify varieties and ensure their stability during seed multiplication, together with legally enforceable constraints by breeders on the multiplication and sale of the seed of their registered and named varieties. The British Society of Plant Breeders collects and distributes the royalties on certified herbage seed sold in the UK. Income from herbage seed sales is much smaller than from any of the other major agricultural species because much less herbage seed is sold. Herbage seed accounted for only 1% of the seed purchased by UK farmers in 2002. This is because seeding rates are low (rarely more than 30 kg/ha) and the more persistent varieties may last for 20 years or more. Seed certification is the final link in the chain and is compulsory for legal seed sales in the UK. Certification ensures varietal purity and freedom from weed species, and it also helps to protect against piracy of varieties by rival seed companies.
VCU and DUS trials currently provide all the data for addition of new herbage varieties to all three UK recommended lists (for England and Wales, Scotland and Northern Ireland), although recommendation remains provisional until further Recommended List Trials are completed.
The development of VCU trials for the UK and associated research
VCU trials for the UK National List were introduced in response to European Union (EU, formerly the EEC) legislation requiring member states to restrict the sale of seed to varieties of specified crops which could be included in their own National List (NL) or in the NL of another EU member. This list covers all the grass and legume species likely to be used for forage in the UK. Records of listed varieties are maintained in the European Common Catalogue. The legislation defines the criteria for VCU: “The value of a variety for cultivation and use shall be regarded as satisfactory if, compared to other varieties accepted in the catalogue of the Member States in question, its qualities, taken as a whole, offer, as least as far as production in a different region is concerned, a clear improvement either for cultivation or as regards the uses which can be made of the crops or the products derived from there. Where other, superior characteristics are present, individual inferior characteristics may be disregarded”. Another EU directive (EC/72/180) specifies that yield, rhythms of production, resistance to diseases and herbage quality should be assessed. This legislation gives scope for differences among Member States in the weightings that they give to different traits. It does not specifically include traits likely to benefit the agricultural environment (apart from disease resistance which could affect fungicide use), but it does not specifically exclude them either. The legislation also does not explicitly include testing varieties to assure protection of animals or humans from possible adverse effects on their health (except for genetically modified varieties), but it does provide for member states to prevent the marketing of varieties found to pose such threats. Minor agricultural species, not listed in the legislation, can be marketed without undergoing VCU trials. The EU legislation was first incorporated into UK legislation in The Seeds (National List of Varieties) Regulations, following the entry of the UK into the EU in 1973. These regulations were amended in 1982 and later replaced by the Seeds (National List of Varieties) Regulations 2001. A VCU requirement for all major agricultural species has been retained in the current EU and UK regulations. A recent government report has recommended that Defra should negotiate to have the VCU requirement removed from the EU seed and plant breeding directives (Better Regulation Task Force, www.brtf.gov.uk/taskforce/reports/Scientificresearch.pdf). However, it is quite possible that some of the other EU members will not agree to this.
The Scottish Agricultural Collages began testing began testing the performance of grass varieties in 1951, and their first recommended list of herbage varieties (North of Scotland College of Agriculture Leaflet 33) was published in 1960. The Northern Ireland Plant Testing Station began trials at Crossnacreevy in 1955 and published their first recommended list in 1972. The National Institute of Agricultural Botany (NIAB) began trials of herbage varieties at four sites in England and Wales in 1961 and published their first recommended list (Farmers Leaflet No. 16) in 1968. VCU testing was Implemented by combining the majority of these Recommended List (RL) trials of candidate varieties that were already in operation. For more detailed accounts of the development of VCU trials in the UK, see Aldrich (1987) and Weddell et al. (1997). VCU trials in the UK have been administered by Defra (formerly MAFF) and advised by a UK interdepartmental group of technical experts (the Herbage VCU Group).
The cost of herbage variety trials has become an increasingly important consideration, because of progressive decrease in support for trialling from public funds and the relatively low value of herbage species to private seed companies. The cost of trials is partly affected by the number of sites, because each site carries the fixed costs of at least one suitably qualified person with experience in herbage variety evaluation together with specialised equipment (forage plot harvester and high capacity drying ovens), regardless of the number of plots harvested. Statistical analysis of the dry matter yields of perennial ryegrass, Italian ryegrass, timothy and cocksfoot at 11 sites over a 10-year period indicated that variety/site interaction was small although variety/year interaction was considerable under the silage (infrequent cutting) management (Talbot, 1984). After examining the testing system and sites in use at the time, it was concluded that extra replicates could substitute for sites without great loss of accuracy in ranking varieties for silage yield but they can not substitute adequately for extra sowings and harvest years. Subsequently, the 11 sites used for VCU testing perennial ryegrass in 1974 were reduced to 5 sites.
The technical difficulties of evaluating forage varieties for use in a wide range of animal production systems were recognised from the outset. Direct evaluation of varieties by animal production experiments is impractical, for two reasons. Firstly, it is enormously expensive to evaluate even a few varieties in this way. Secondly, the results of any animal production experiment will vary according to the particular factors limiting animal production at the time. Thus herbage variety evaluation depends on measuring traits in small plot trials that are important for animal production: dry matter yield and its seasonal distribution, persistency, components of herbage feeding value, and factors affecting reliability (such as frost tolerance, and resistance to several plant pathogens). The management of the trials and the collection and interpretation of the data have been continually revised in the light of research findings, although some findings have yet to be fully addressed.
An important question is whether the regular close cutting used to simulate grazing is an adequate substitute for actual grazing. There was good, although not perfect, agreement in the ranking of six diploid perennial ryegrass varieties in annual dry matter yield (DMY) and persistency under simulated grazing and under rotational grazing by cattle or sheep (Aldrich, 1974). Similar results were obtained when ten diploid Italian ryegrass varieties were compared under simulated grazing and under rotational grazing by cattle (Camlin and Stewart, 1975). The annual DMY of diploid and tetraploid perennial and hybrid ryegrass varieties continuously grazed by sheep did not correlate significantly with results from an adjacent cutting experiment or with results from simulated grazing in NIAB RL trials (Orr et al., 2001). However, this experiment was not designed specifically to detect variety/management interactions and does not provide direct evidence of such interaction. It is also worth noting that the cutting regime used was actually closer to the VCU conservation management than the VCU simulated grazing management. Under continuous grazing in this experiment differences among varieties in annual DMY were barely significant statistically, so a strong correlation with yield under simulated grazing would not have been expected. Thus the research on ryegrass varieties has not provided convincing evidence of interaction between the persistency and DMY of ryegrass varieties and the method of harvesting. However, such interaction can be important with other grass species. Some cocksfoot varieties declined markedly in annual DMY from the first to the second harvest year when subjected to rotational grazing, but not when subjected to cutting (Papadopoulos et al., 1995). Cocksfoot is known to be much more susceptible to damage from heavy treading than ryegrass (Edmond, 1964), which could explain why some cocksfoot varieties do not persist well under grazing. Such a situation could conceivably arise with new ryegrass varieties if treading tolerance declined after several generations of breeding for herbage quality, DMY and persistency in the absence of treading. White clover varieties do rank differently in DMY and ground cover under simulated rotational grazing and under continuous grazing by sheep (Evans et al., 1992; Swift et al., 1992). Much of this interaction can be accounted for by differences in variety leaf size; large-leafed varieties persist best under both simulated grazing and light cattle grazing while small-leafed varieties persist best under sheep grazing (Morrison, 1997). Varieties of white clover in the medium-leaf-size category ranked very differently in DMY under simulated rotational grazing and under continuous grazing by sheep (Williams et al., 2001). However, these varieties gave similar rankings in ground cover to those obtained under the persistency management (very frequent close cutting) that is currently used in VCU trials. Thus although the evidence is inconclusive for the major UK species, it indicates that testing general-purpose herbage varieties for their ability to persist under actual grazing is desirable, although currently it is not essential for VCU purposes. Evaluation of persistency under cattle grazing requires larger plots than do cutting trials, because of lower uniformity due to damage from dung and urine patches, and thus much more seed is required for trials that utilise cattle grazing. It can be difficult for breeders to supply enough seed for such trials during the early stages of variety development. Thus testing for persistency under grazing is more appropriate for recommended list trials than for VCU trials.