bluuebunny/crossref_metadata_2025 huggingface dataset:
Recurrent selection for grazing tolerance in winter-active populations of the perennial grass, Phalaris aquatica L.
Authors: Culvenor Richard , Boschma Suzanne , Reed Kevin
Published: March 2021

Phalaris (Phalaris aquatica L.) is a perennial grass of Mediterranean origin used widely by the sheep and cattle industries of south-eastern Australia. Winter-active cultivars released since the 1970's have the potential for higher herbage productivity than the earlier, semi-winter dormant cultivars but have been reported to be less persistent under sub-optimal grazing management and soil conditions. To improve genetic potential for persistence in winter-active phalaris, a program of recurrent selection was conducted by subjecting three populations of half-sib families to two cycles of selection for persistence under heavy, largely continuous grazing pressure. Cycle 2 progeny families and bulked seedlots of each generation were grown in separate grazed plot trials in Western Victoria and the Southern Tablelands and North-West Slopes of New South Wales from 1999-2003 to assess response to selection. Positive linear response to selection was observed in all populations at the Western Victorian and Southern Tablelands sites. Response to selection was absent and persistence was very low under higher temperature and drought stress on the North-West Slopes. This high level of genotype Ã— environment interaction for persistence was also observed among final generation families. Families with better persistence than current winteractive cultivars at the two southern sites were identified in each population and a new cultivar is being formed from the parents.
Statistical methods to address spatial variation in pasture evaluation trials
Authors: Murison Bob , Ayres John , Lane Leah , Woodfield Derek
Published: March 2021

The primary breeding objective for white clover improvement in eastern Australia is more reliable persistence under summer moisture-stress while maintaining herbage production (especially winter growth). To identify elite germplasm, evaluation of candidate lines is done in situ, under field conditions for which the prospective cultivar is targeted. These conditions (e.g. moisture stress, nutrient infertility, grass competition) may impose spatial influences within the field site that as artefacts mask or alter the uniform expression of response to environment. A significant component of artefact variation which affects interpretation of the data is the spatial variation due to plot position. Failure to correct for this may give unreliable comparisons as some lines inadvertently (through randomisation) are allocated to favourable or unfavourable plots. Our methodology was developed at two sites (Glen Innes , Armidale in northern New South Wales, Australia) in an experiment which sought to identify superior lines among 20 candidate entries. Cultivars of reputed stability and spanning the expected performance range, are replicated at regular intervals through the field site. The difference amongst replicates within cultivar (that is a reduced G X E) is used to estimate spatial trends. Elite lines are identified from temporal profiles of plant performance related to the breeding objectives. We describe (i) design and analysis which allows estimation of the spatial effects, and (ii) the temporal profiling of plant performance. These statistical procedures are seminal in identifying superior breeding lines that subsequently proceed to cultivar development.
Slugs as Pasture Pests
Authors: Wilson M.J. , Barker G.M.
Published: March 2021

Several invasive European slug species are thriving in New Zealand and have become important pests of many crops. In pasture, they are particularly damaging to white clover during renovation and the problem may be exacerbated by direct drilling. Slug feeding causes both lethal and sublethal damage that reduces clover establishment and thus pasture quality. Much less is known about slug damage to established pastures and the degree to which slugs limit pasture persistence. Established pastures frequently support large slug populations that feed on clover and the application of molluscicides can reduce slug numbers and increase the proportion and yields of clover. Future research on these pests should concentrate on determining damage thresholds, breeding resistant clover varieties and developing agronomic practices that favour natural enemies. In the long term, there is much potential for developing microbiological pesticides that target slugs. Keywords: molluscs, slugs, clover
What factors lead to poor pasture persistence and weed ingress?
Authors: Tozer K.N. , BourdÃ´t G.W. , Edwards G.R.
Published: March 2021

In an ideal pasture, sown species would persist indefinitely and there would be no weeds. 'Poor persistence' occurs when the desirable species are replaced by weedy, undesirable species. Unfortunately, poor persistence of sown pasture plants is the reality that most farmers experience. In this paper we review the literature on three key factors leading to poor persistence and weed ingress: 1) inter-specific competition; 2) sward disturbance; and 3) propagule pressure. We reveal that grazing and other management decisions, pasture insect pests, nutrients, climate and the composition of the sown species mix have a critical influence on these factors, and hence over the replacement of sown pasture plants by weeds. The key practical message from this review is that farm practices that improve the vigour of sown species, reduce pasture gaps and minimise weed propagule pressure will improve the persistence of sown species and minimise weed ingress. An outstanding deficiency is our lack of knowledge of the economic impacts, and hence weed status, of most of the ca 187 volunteer plant species that may invade and replace sown plants in New Zealand's pastures.
Effect of soil physical condition, and phosphorus and nitrogen availability on pasture persistence
Authors: Mackay A.D. , Gillingham A. , Smith C. , Budding P. , Phillips P. , Clarke-Hill W. , Johnstone P.
Published: March 2021

Soils are the substrate at the base of any grazing or cropping system providing plants with nutrients, water and physical support, a habitat for beneficial organisms and a physical base on which animals stand. A change or a loss of any one of these soil services has the potential to impact on plant growth and persistence. The findings of two ongoing field-based studies are presented and discussed as they relate to the current debate on pasture persistence. One study is investigating the influence of the physical condition of the soil on a ryegrassbased pasture response to added phosphorus (P). The second study is investigating the P requirements of high producing perennial ryegrass and tall fescuebased pastures, where the constraints to pasture growth and associated P uptake imposed by low nitrogen availability and low soil moisture over summer-autumn have been removed. The critical Olsen P value for maximum pasture production appears to increase as the constraints to pasture growth are removed. This challenges the continued use of a single relative yield Olsen P function and one critical Olsen P value for near maximum yield regardless of the absolute pasture yield. Loss of soil pore function also appears to increase the critical Olsen P value necessary for optimum pasture growth. Additional P can compensate for a lack of pore function to a degree, but there appears to be an upper limit to this effect. Given that the physical condition of many of our pasture soils in intensive lowland situations is below optimum, nutrient stress may be more of a factor in poor pasture-persistence, than previously thought. Inclusion of a measure of soil physical condition would appear to warrant further study in defining the conditions for optimum plant growth and persistence. Keywords: fertiliser nitrogen, Festuca arundinacea, Lolium perenne, Olsen P, pasture persistence, soil pore function, soil services
Delivering Endophyte Benefits on-farm: Pasture Renewal Success and Effects on Pest Invertebrates
Authors: Rennie G.M , King McG , Bell N.L. , Eden T.M.
Published: March 2021

New pasture grassâ€¦
Pasture persistence: how much is it worth?
Authors: Brazendale R. , Bryant J.R. , Lambert M.G. , Holmes C.W. , Fraser T.J.
Published: March 2021

The farm system model, Farmax Dairy Pro, was used to evaluate the impact of new pastures on dairy farm profitability, assuming a range of pasture yields and qualities, and different levels of persistence in the new pastures, which were established on 10% of the farm annually. Scenarios were tested for Waikato, Taranaki, Canterbury and Southland dairy farm systems. Assuming a $6.50/kg MS milk payment and a response to pasture renewal of 10% in dry matter yield and a 0.6 MJ ME/kg DM increase in quality, increasing persistence from 4 years up to 8 years was modelled to increase dairy farm profitability by $271/ha to $478/ha. Management practices, including selections of cultivars and endophytes, that improve pasture persistence are likely to increase dairy farm profitability. Keywords: dairy farms, modelling, pasture renewal, persistence
Pasture persistence: farmer observations and field measurements
Authors: Tozer K.N. , Cameron C.A. , Thom E.R.
Published: March 2021

Information is presented on farmer perceptions and concerns regarding key factors leading to poor persistence of sown pasture species. Forty-seven farmers from four regions viz. Northland (beef, sheep), Waikato (dairy), Taranaki (dairy) and North Canterbury (beef, sheep, deer) were asked for their opinions on the 'keys' to persistence and 'killers' of sown species; i.e., factors leading to a decline in sown species. In all regions, grazing management was perceived to be the most important key to persistence and insect pests the top killer of sown species. Better industry dissemination of existing information and further research on forage herbs and insect pest issues are future requirements. In each region, presence of sown species was also assessed in 30 paddocks belonging to the surveyed farmers. There was a significant decline in pasture chicory presence, but no decline in that of cocksfoot or plantain. Ryegrass, white clover and tall fescue were present in nearly all paddocks in which they were sown. Chicory may be best used as a crop, while plantain shows greater potential for persistence as part of a pasture mix. Keywords: chicory; farmer survey; information gaps; plantain; research needs
Sowing methods for successful pasture establishment - a review
Authors: Thom E.R. , Fraser T.J. , Hume D.E.
Published: March 2021

Methods of achieving successful pasture establishment have been broadened over the last 50 years by the introduction of no-tillage technologies, providing a viable alternative to cultivation. Parallel developments in drill technologies for seed and fertiliser placement, and methods to control competition from the existing pasture have ensured the success of no-tillage methods. This review focuses on the effects of the establishment method on seedling growth over the establishment period, defined for the purposes of this paper as the year after sowing. Undersowing existing pasture is the establishment method least likely to provide a suitable environment for seedling growth and development. New pastures must receive different management to existing pastures for at least 1 year after sowing to increase their chances of becoming persistent and productive. Long-term monitoring (5-10 years) of new pastures has received little research attention, making assessments of effects of different establishment methods on persistence difficult. Factors likely to affect seedling establishment and plant survival are discussed. Keywords: competition control, cultivation, directdrilling, first year management, Lolium perenne, ryegrass, seedling survival, Trifolium repens, white clover
Observations and insights on pasture persistence in New Zealand
Authors: Lane P.M.S.
Published: March 2021

This essay contains personal observations and interpretations by the author on the persistence of pastures in the northern North Island. Key pasture stress factors are identified as the increase of farming intensity over the past two decades, the impact of pasture renewal techniques and the role of pasture species on insect pest (particularly black beetle and clover root weevil) interactions. Keywords: insect pests, soil fertility, pasture renewal, cultivars, endophyte
Nitrogen leaching implications of poor pasture persistence
Authors: Betteridge K. , Crush J. , Ledgard S. , Barton M.S.
Published: March 2021

Farmers have indicated that perennial pastures sown in the Lake Taupo catchment revert to low quality species within 8 to 10 years. These may be renewed with perennial pasture species following an autumn then spring cropping regime, or resown pasture-topasture by direct-drilling into glyphosate-sprayed turf or following full cultivation. Vegetation which is desiccated and/or ploughed-under before sowing will decay and release mineral nitrogen (N). The mineral N from these sources is available for newly sown plants but can also be leached. In a large, replicated, rotationally cattle-grazed trial near Lake Taupo, new pasture was established with the high sugar ryegrass (HSG) Aberdart in one treatment only by direct-drilling, following glyphosate application in late summer. Existing pasture remained in Control plots. Renovated pasture leached 63 kg nitrate-N ha-1 in the 8 months following establishment compared 8 kg nitrate-N ha-1 in Control (P
Plant responses to defoliation and relationships with pasture persistence
Authors: Edwards G.R. , Chapman D.F.
Published: March 2021

The effects of defoliation on plant morphology and the structure of perennial ryegrass and white clover populations are reviewed with reference to the persistence of yield in sown pastures. Maintenance of high densities of perennial ryegrass tillers and white clover stolons is fundamental to persistence. Tiller and stolon population densities are subject to within- and between-year variation, and are strongly influenced by defoliation management through processes such as competition for light, and size-density trade-offs mediated by self-thinning processes. Spring is a time when high tiller/stolon appearance and death rates occur simultaneously. Spring is also the time when clover populations undergo rapid structural change as large clover plants fragment to release small, unbranched plants with limited ability to compete for light with grasses. The central role of reproductive stem development in perennial ryegrass for summer survival of tillers and autumn re-establishment of tiller populations also highlights the importance of defoliation management during the spring for population persistence. Examples of the application of tactical defoliation management in spring, and at other times of the year, to manipulate stolon and tiller densities are presented. In some instances, such tactics may improve animal production potential, as well as the persistence of new cultivars. It is notable that the New Zealand literature on this topic is mostly more than 15 years old. Recent changes in farming systems and plant genotypes (e.g. tetraploidy in perennial ryegrass, late flowering perennial ryegrass) may require a reanalysis of established principles and practices related to defoliation x plant interactions in grazed pastures to ensure best possible pasture yield persistence and profitability of grazing systems. Keywords: grazing management, perennial ryegrass, persistence, population dynamics, white clover
FACTORS AFFECTING SCALE OF ENTERPRISE
Authors: Freeman Logan
Published: March 2021

White clover is undersown in the spring with wheat, barley and peas. Irrigation is used in order to achieve a heavy flowering in the white clover crop over one month. Three barley crops must be grown successively in some paddocks to eliminate yarrow. Lupins, peas and soybeans are alternative legumes to white clover, but white clover is still the preferred legume to grow, especially with new cultivars becoming available. Keywords: White clover, Trifolium repens, seed production, yarrow, alternative crops, overseas markets.
ASPECTS OF SEED QUALITY
Authors: Scott D.J. , Hampton J.G.
Published: March 2021

Seed quality refers to a number of seed properties which may have varying degrees of practical importance for agriculture. As well as the traditional purity and germination capacity of seedlots, seed quality also includes species purity, cultivar purity, vigour, seed size, seedlot uniformity, seed health and seed moisture content. The quality of New Zealand herbage seedlots is reviewed. Data are presented for weed seed contamination, germination, seed vigour and seed weight. The influence such factors as analytical and cultivar purity, freedom from weeds, vigour and seed health have on New Zealand's domestic and export seed trade is discussed. Keywords: Seed quality, herbage seed, analytical purity, weed seeds, cultivar purity, germination, vigour,
Adoption of herbage cultivars - an extension rationale
Authors: French R.A. , Simmonds J.G.
Published: March 2021

Over the past 10 years, 14 new herbage cultivars have become available to New Zealand farmers. Each cultivar has the potential to increase total and/or seasonal dry matter (DM) production. Many have other desirable features such as insect resistance, improved palatibility, better persistence and adaptability. Yet despite these obvious advantages, many plant breeders, advisers and commerical agents are repeatedly asking, why aren't the majority of pastoral farmers quickly adopting these new improved grass and legume cultivars?
Establishing and managing recent cultivars in arable dryland pastures
Authors: Hume D.E. , Fraser T.J.
Published: March 2021

Grass and legume species/cultivars available to farmers in the summer dry east coast of New Zealand, other than the traditionally used perennial ryegrasslwhite clover, fall into 3 categories: 1. drought tolerant species/cultivars which will maintain production later into summer and respond quickly after drought, e.g. cocksfoot, tall fescue, lucerne, prairie grass. 2 . species/cultivars which will maximise production in winter and spring, e.g. prairie grass, phalaris, subterranean clover. 3. species/cultivars compatible with summer crop programmes e.g. annual ryegrasses.
Environmental and agronomic constraints in dryland pasture and choice of species
Authors: Hoglund J.H. , White J.G.H.
Published: March 2021

Hawkes Bay in the north down to North Otago, the duration and intensity of summer drought is unpredictab!e and variable. Within this region, winter temperatures are generally high enough to allow slow growth of pasture but summer drought can completely halt growth in most years, particularly on the commonly found shallow free draining soils. On these soils, moisture stress can develop very quickly because of the limited available soil water. Nearer the foothills, rainfall is greater and severe moisture stress less common. On sunny aspects in hill country however soils are commonly below wilting point for over six months of the year.
Pasture Management And Winter Feed
Authors: Anon A.
Published: March 2021

One of the main objectives of pasture management is to meet the annual feed demand of stock by manipulating the annual feed supply from pasture. This challenge is probably greatest for high country runholders because long cold winters and often dry summers severely disrupt the continuity of pasture growth and create a mismatch between supply and demand. Within each high country run there is generally a diverse range of landscapes environments whose integration with planning, and an appropriate choice of pasture species, and selective management, can help overcome this mismatch.
BROWNTOP
Authors: Brown K.R. , Wilson R.S. , Blakemore N.
Published: March 2021

Sefton browntop is a new Grasslands cultivar. At present there are three growers entering Sefton for certification, with a total of 22 ha sown. Yields average around 150 kg ha-'. Egmont browntop is more established in the New Zealand herbage seed industry. Thirty-five growers entered crops for certification in 1988, amounting to 200 ha.- Yields average around 150 kg ha-' but yields of 450 kg ha" have been recorded.
SEED AGENCIES FOR GRASSLANDS' CULTIVARS
Authors: Lancashire J.A.
Published: March 2021

The seed agency system was set up in New Zealand to inject some netl; life into the industry. Over the past 30 years the New Zealand Herbage Seeds Industry has been in a no-growth phase: it has not expanded; the amount of certified seed has been static, if not declining; exports have stayed at the same level in terms of percentage of total exports; the-amount of pasture renewal has stayed at 2-3% of the total pasture area. During this time there was little promotion of the different cultivars of grass seed, presumably because individual companies were reluctant to spend money on advertising which would not benefit them specifically. By bringing in a system whereby individual companies within New Zealand have the responsibility for individual cultivars, expenditure on promotion is directly recoupable by the company doing the promoting. Furthermore, planned marketing with amounts of seed grown being linked into projected markets which have been created or developed both here and overseas, is possible.
SEED PROCESSING
Authors: O'Neill P.
Published: March 2021

Co-operation, tolerance, communication and planning are necessary at harvest 1 time, and can help minimise delays and difficulties when off-loading seed at the processing plant. In normal circumstances the first areas of concern on the seed's arrival into store are the condition of the seed and the certification requirements. These areas have been dealt with in other papers, so this paper will concentrate on the post-harvest treatment of seed. A common fault in ryegrass harvesting is to. include a large amount of light trash, straw and empty glumes in the sample. This creates problems when dressing, for although the rubbish can be removed relatively easily and the weight loss may not be excessive, production from the plant is likely to be reduced because of the volume passing through the machine. Furthermore, in an effort not to lose good seed the operator may tend to cut back on 'blast'. This in turn may result in an inferior Purity and Germination test because of the inert matter content.
THE FLOWERING AND SEEDING PROCESS
Authors: Langer R.H.M.
Published: March 2021

Whether one is a butcher, baker, candlestick-maker, seed producer or traffic officer one needs to understand the,components of the system one is dealing with before one can understand the system itself. Traffic officers, for example, need to know about cars and how they work (lights and brakes and all things subject to a warrant of fitness). For any job, however simple it appears, one must understand the components of the system in order to understand the system.
HARVEST - THE WEEK BEFORE AND ON THE DAY
Authors: Marr G.
Published: March 2021

The first rule in harvesting is not to panic. The second is to plan ahead and prepare the machinery months in advance so that everything is ready when the time comes. As a general rule when the cocksfoot crop flowers at Methven there are 28 days until harvest; when close examination of the seed kernel indicates that it has passed from the milk to dough stage, there are seven days. left. Cocksfoot is judged to be ripe when seed drops into a hat swept through the crop. If in doubt an infra-red lamp is used. After cutting, the crop is windrowed high, parallel to the prevailing wind. A secondary cut with the rotary mower increases wind protection and improves ease of pickup.
Environmental impacts of nitrogen in pastoral agriculture
Authors: Carran R.A. , Clough T.
Published: March 2021

The principal environmental impacts of nitrogen in pastoral agriculture are identified as: ammonia volatilisation, nitrous oxide emission, reduction of methane oxidation, and contamination of waters with organic nitrogen or inorganic nitrogen (nitrate, nitrite and ammonium). Each of these impacts is analysed in terms of its sensitivity to the form in which N enters the farming system, symbiotically or as fertiliser. Indirect effects that flow through from any changes in productivity are also examined. With the exception of organic N pollution of waters, all the impacts are shown to be directly affected by fertiliser N. Keywords: ammonia, leaching, methane, nitrate, nitrous oxide
A farmer's experience with high N fertiliser inputs on grass/clover pastures
Authors: Barr Stephen
Published: March 2021

A dairy farmer's experiences in managing various levels of fertiliser nitrogen (N) inputs over the 1991-95 seasons is discussed and compared to previous years when very little N fertiliser was used. N requirements were assessed by regular herbage tests. Fertiliser N increased pasture growth in spring, early summer and autumn. Animal intakes were greater on N-boosted pasture. Higher rates of N fertilisers (450 kgN/ha/yr) generated large spring surpluses which were harvested as silage. Several changes in management were required to maintain pasture quality and effectively utilise these surpluses. Feed costs vs milk returns are compared for a number of seasons. Moderate fertiliser N usage (200- 300 kg N/ha/yr) is considered likely to give the most profitable balance. Keywords: clover, dairying, grazing management, milksolids, nitrogen, pasture growth, pasture quality
The value of N-fixation to pastoral agriculture in New Zealand
Authors: Walker T.W.
Published: March 2021

White clover in New Zealand fixes nitrogen equivalent to 4.5 million tonnes of urea annually. Experiments on the tactical use of about 50 kg N ha-1 yr-1 to stimulate grass growth when clovers are less active indicate that it is generally profitable, but much heavier dressings have rarely been shown to pay at current cost/price structures. The significance of biological nitrogen fixation (BNF) cannot be measured solely by dry matter yields as the quality of herbage is influenced by the contribution of clover and affects yields of animal products and health. Our dependence on BNF gives us a relatively low energycost system of pastoral farming because of the high energy cost of producing fertiliser-N and is therefore more sustainable. The heavy use of fertiliser-N suppresses clover growth and N-fixation, increases losses of ammonia and nitrous oxide to the air and nitrate in drainage water. The extra stock carried leads to greater emission of methane. Reliance on clovers may give lower production but lessens damage to the environment. Keywords: biological nitrogen fixation, energy costs, environment, fertiliser nitrogen, pastoral agriculture, sustainability
Breeding strategies for developing transgenic white clover cultivars
Authors: Woodfield D.R. , White D.W.R.
Published: March 2021

The introduction of foreign genes into elite white clover (Trifolium repens L.) genotypes has resulted in the first field test of genetically modified white clover. We now require breeding strategies which efficiently deploy transgenes into commercial cultivars. Current white clover cultivars are synthetics, produced by randomly intermating selected parents or seed lines for up to 6 generations. Unfortunately, the uncontrolled nature of transgene insertion means each transformant has a different site of insertion and frequently has a variable number of inserts. This complicates breeding strategies because populations produced by intercrossing these transformants will contain multiple insertion sites, variable dosage at each insertion site, and be highly heterogeneous for expression level. A modified synthetic breeding method is proposed for crosspollinated crops such as white clover which overcomes these difficulties by identifying F2 progeny homozygous for a defined number of transgenes. These homozygotes are used as the parents to develop a synthetic with a specific genetic composition and high expression levels of the transgene in all progeny. The advantages of backcrossing into existing cultivars or directly transforming inbreds are also discussed. The initiation of new crossing programmes in successive years can be utilised to offset the initial lagphase until strategies which reduce the number of generations required to obtain commercial quantities are developed. Keywords: backcrossing, breeding methods, cross-pollinated, hybrids, inbreeding, plant breeding, transgenic plants, Trifolium repens L.
Deferred grazing to enhance white clover content in pastures
Authors: Watson R.N. , Harris S.L. , Bell N.L. , Neville F.J.
Published: March 2021

During the early 1990s declining milk yields on coastal Bay of Plenty farms, against wider district trends, was attributed to pasture clover deficiency. To investigate possible causes pasture herbage yield, species composition, white clover growing point density and N-fixation activity were measured on two coastal Bay of Plenty dairy pastures over two years following nematicide treatment (Watson et al. 1994). Soil temperature was also monitored over most of this period. There was a marked decline in white clover growing point density of up to 90% from mid-December to mid- February in each year. This coincided with periods when surface (1 cm depth) daily maximum soil temperatures exceeded 30Â°C and soil moisture levels were below 30% Mw. Loss of clover was enhanced by clover cyst (Heterodera trifolii) and root knot (Meloidogyne spp.) nematodes which also delayed autumn recovery. Poor clover levels taken into the winter extended clover deficiency into a second season. Keywords: drought, grazing management, stolon density
Water stress and water use efficiency of ten white clover cultivars
Authors: Barbour M. , Caradus J.R. , Woodfield D.R. , Silvester W.B.
Published: March 2021

Ten cultivars of white clover were grown in a glasshouse at three levels of soil moisture. Leaf productivity was greatly reduced by moisture stress. The productivity of cultivars was found to be significantly different under well-watered conditions. Larger-leaved cultivars tended to be more productive than those with smaller leaves, but this difference was lost at high moisture stress creating a significant cultivar by moisture treatment interaction. Water use efficiency (WUE) increased with increasing moisture stress, but within any one moisture level there were no significant differences between the cultivars. An integrated measure of WUE is captured by the level of discrimination against 13C in plants tissue (Ã„). Over the range of moisture levels used, a strong negative correlation was found between Ã„ and WUE. A strong positive correlation was found between productivity and Ã„ over the range of moisture treatments, however, within any one moisture level no significant relationship was established. Keywords: carbon isotope discrimination, cultivars, moisture stress, Trifolium repens, water use efficiency
The incidence of insect pests and their Arthropod predators in 24 Canterbury white clover seed crops
Authors: Schroeder Neil , Clifford Peter
Published: March 2021

Insect pests and their predators were sampled in Canterbury white clover crops during the 1994-95 season. Bluegreen aphid and potato mirids occurred early (late October to mid-November) during the season and were a potential cause of major injury to developing flowerheads. Australian crop mirid, wheat bug, brown shield bug, and spittle bugs occurred later in the season during January and were more likely to affect seed fill and resultant seed quality. Bluegreen aphids reached an overall maximum number of 800 per m2 during early December, while potato mirid nymphs and adults were found in significantly (P
Paclobutrazol and white clover seed production: a non-fulfilled potential
Authors: Hampton J.G.
Published: March 2021

Seed yield in white clover depends largely on the number of ripe inflorescences per unit area, and the plant growth regulator paclobutrazol has been used in an attempt to both increase and concentrate inflorescence production, and hence increase seed yield. However results reported from both New Zealand and Europe have been inconsistent, with seed yield responses ranging from highly significant increases to no effects. The current high cost of the chemical ($1280/ha) requires a seed increase of over 300 kg/ha to ensure an economic return. Similarly no consistent effects of paclobutrazol on white clover vegetative and reproductive growth and development have been established. Possible reasons for this variable response of white clover to paclobutrazol application are presented and discussed. Keywords: inflorescence production, Parlay, reproductive growth, seed yield components, Trifolium repens, vegetative growth
A review of the role of grazing management on the growth and performance of white clover cultivars in lowland New Zealand pastures
Authors: Brock J.L. , Hay M.J.M.
Published: March 2021

The current state of knowledge of white clover clonal growth processes and defoliation management is reviewed, and general recommendations on grazing principals made. Defoliation frequency determines herbage productivity through the manipulation of size/ density compensation between plant organ size (leaves) and numbers of growth units (growing point density). Hence large-leaved cultivars (Pitau, Kopu, Aran) are generally more productive under rotational grazing, whereas small-leaved cultivars are better suited to frequently grazed or set stocked conditions (Tahora, Prestige). The key to persistence is high growing point density, and the development of large-leaved densely branched cultivars should have superior performance over a wider range of grazing managements (Demand, Sustain). Grasses (perennial ryegrass, cocksfoot and tall fescue) grow by similar clonal processes to white clover and react in a similar manner to grazing management. Maintenance of pasture density (growing points/tillers) is crucial to persistence and is best achieved by rapid rotations or set stocking during spring/early summer. This provides protection against drought, and allows better exploitation of the genetic potential of species and cultivars through alternative grazing strategies over the remainder of the year. Keywords: clonal growth, cultivars, grazing management, morphology, populations, rotational grazing, seasonal growth patterns, set stocking, Trifolium repens L., white clover
Long-term effects of pastoral fallowing on the distribution and performance of white clover (Trifolium repens L.) in a hill country pasture
Authors: Nie Z.N. , Valentine I. , Mackay A.D. , Barker D.J. , Hodgson J.
Published: March 2021

Previous work found that white clover (Trifolium repens L.) yield initially decreased, but subsequently increased following a pastoral fallow. The objective of this research was to quantify the response in herbage production and stolon characteristics of white clover up to 4 years after fallowing. Four treatments were used: fallowed 1990/91 (F4), fallowed 1991/92 (F3), fallowed 1993/94 (F1) and non-fallowed (F0). The fallowing period was between September and May. White clover dry matter yield (between 15/12/94 and 18/5/95) was significantly greater for the treatment F4 than F0 (P
Endophyte in New Zealand ryegrass pastures, an overview
Authors: Easton H.S.
Published: March 2021

Ryegrass pastures in New Zealand are usually infected with the ryegrass endophyte (Neotyphodium lolii). The endophyte provides protection from invertebrate attack, discourages overgrazing by livestock and perhaps confers other advantages enhancing ryegrass persistence. The endophyte lifecycle is completed within the plant, and transmission is uniquely through the grass seed. Within the plant, the endophyte synthesises a range of compounds, some of which have been identified as responsible for known endophyte effects on pasture invertebrates and on livestock. The concentrations of these compounds vary in different parts of the plant, with plant age and in response to environmental influences. While endophyte has wellknown adverse effects on livestock (reviewed elsewhere in this volume), it contributes positively to grassland productivity in New Zealand. Keywords: endophyte, Lolium, Neotyphodium lolii, pest resistance, ryegrass
Molecular biology of Epichloe endophyte toxin biosynthesis
Authors: Scott Barry , Young Carolyn , Mcmillan Lisa
Published: March 2021

EpichloÃ« endophytes are an important group of filamentous fungi that confer on the grass host a range of biological benefits. However, endophyte synthesis of ergopeptine and indole-diterpene mammalian toxins in pasture grasses is detrimental to livestock grazing on that forage. The molecular cloning of the genes involved in the biosynthesis of these toxins will enhance our ability to maximise the beneficial attributes of this mutualistic association through the availability of DNA probes to screen and select for desirable endophytes and through our ability to genetically modify endophytes. Genes involved in the biosynthesis of both classes of alkaloids have recently been cloned from Claviceps purpurea and Penicillium paxilli. In both cases the genes are organised in large clusters; a feature that will facilitate a complete genetic analysis of each pathway and provide probes for isolating homologous genes from EpichloÃ« endophytes. This paper reviews recent research developments on the molecular biology of these two pathways. Keywords: EpichloÃ« endophytes, ergopeptines, gene cloning, gene manipulation, indole-diterpenes
Ergot alkaloids additional to ergovaline in endophyte-infected perennial ryegrass and tall fescue in New Zealand
Authors: Lane G.A. , Tapper B.A. , Davies E.
Published: March 2021

Several ergot alkaloids additional to ergovaline have been identified in perennial ryegrass and other grasses infected with Neotyphodium spp. endophytes. The identification of the ergot alkaloids ergine, chanoclavine-I and dehydroergovaline, from New Zealand samples of endophyte-infected tall fescue and perennial ryegrass is reported and discussed. Keywords: chanoclavine-I, dehydroergovaline, endophyte, ergine, ergot alkaloid, Neotyphodium spp., ryegrass, tall fescue
Survival of endophyte-infected ryegrass seed buried in soil
Authors: Hume D.E. , Rolston M.P. , Baird D.B. , Archie W.J. , Marsh M.R.
Published: March 2021

Emergence of volunteer perennial ryegrass (Lolium perenne L.) from seed buried in soil may contribute to the ingress of ryegrass in newly sown pastures. To investigate this, ryegrass seed infected with fungal endophyte (Neotyphodium lolii) was buried in nylon bags under pasture at two depths and at two sites (Palmerston North, Lincoln) in early/mid-autumn 1998. Seed bags were removed from the soil at intervals over the course of one year to determine seed viability and presence of endophyte in seedlings. Viability of seed declined rapidly to be 10% 3 months after burial. Further decline in viability was less, so that 12 months after burial 4% of seeds were still viable. Endophyte viability also declined, from 58% infection of seedlings at the time of burial to 21% at 12 months. This was at a slower rate than the decline in seed viability and from what might have been predicted from seed storage experiments. Viability of seed buried at 10 cm was greater than that buried at 3 cm (e.g., means, 10% and 1% after 6 months, respectively). This has implications for cultivation practices before pasture establishment. Seed buried at Lincoln maintained higher viability than seed buried at Palmerston North (e.g., means, 6% and 4% after 6 months, respectively), which was associated with drier soil conditions at Lincoln. Survival of buried seed may therefore be of greater importance in summer-dry east coast regions, compared with moist west coast environments or in wet years. The significance of buried ryegrass seed will depend on the numbers involved, but after 12 months there were still viable seeds left in the soil and some of these were infected with endophyte. This is important for pastures sown with ryegrass that is free of endophyte or infected with a selected endophyte, and for slower establishing grass species such as tall fescue. Keywords: endophyte, endophyte survival, Lolium perenne, Neotyphodium lolii, perennial ryegrass, seed burial, seed survival
Ryegrass endophyte and cattle growth in Northland
Authors: Easton H.S. , Couchman J.N.
Published: March 2021

Perennial ryegrass pastures infected with or free of the endophyte (Neotyphodium lolii) were compared for growth and health of young grazing cattle. Heat stress, indicated by excessive salivation, was observed on several occasions among cattle grazing endophyte-infected ryegrass, but there were no differences between groups in body temperature. Liveweight gains were generally slow and inconsistent. During one period of rapid liveweight gain in March-April 1997, heifers grazing endophytefree pastures gained 7 kg more than heifers grazing infected pasture. Taking data from three four-week grazing periods in summer and autumn, liveweight change of cattle grazing endophyte-free pastures showed a consistent advantage over cattle grazing endophyte-infected ryegrass. Significant differences in serum prolactin were recorded on two occasions, and on one day in February 1998 weaner bulls grazing infected ryegrass were breathing significantly faster than their counterparts on endophyte-free pasture. These results can be compared with previous reports that endophyte status of ryegrass pastures has little effect on grazing cattle, and contrast with the published literature for tall fescue. Keywords: liveweight gain, Neotyphodium lolii, perennial ryegrass, ryegrass endophyte
Endophyte and dairy production in New Zealand: experience at the Dairying Research Corporation
Authors: Thom E.R. , Clark D.A. , Waugh C.D.
Published: March 2021

Sixteen short term tests of the effects of ryegrass (Lolium perenne L.) endophyte on milk production from dairy cows were carried out at Dairying Research Corporation (DRC) sites in Taranaki (1992/93) and Waikato (1993-1999). Increasing contamination of endophyte-free areas with volunteer endophyte-infected ryegrass could have modified milk production responses to endophyte in the first of two trials in the Waikato (1993- 1996). Test periods were in spring, summer and autumn. Significant effects of endophyte on milk production were detected on only 4 occasions. Small (
Influence of nutrition and lactation on ovulation and conception in red deer
Authors: Asher G.W. , Pollard J.C.
Published: March 2021

Reproduction incurs a high energetic cost and failure to meet nutritional needs results in reproductive failure. In red deer hinds, the interaction between nutrition, summer lactation and subsequent ovulation/conception is of particular interest for farmed deer production in NZ due to climatic constraints to summer pasture production in many areas. However, few studies have focussed on the potential perturbing effects of poor nutrition on lactational outputs and potential flow-on effects on ovulation/conception. As lacta tion in red deer naturally persists well beyond the autumn mating period, lactational anoestrus (through hormonal feedback mechanisms) is not a normal feature of the species reproduction. However, lactation is of high nutritional cost to the hind and can potentially exert considerable influence on the incidence and timing of conception via changes in hind liveweight, lipid depots and general body condition. Supporting evidence for this hypothesis is derived from studies of wild red deer within habitats marginal to species survival (e.g. Isle of Rhum, Scotland), where climatic variables greatly influence annual reproductive success of hinds. Under such conditions, even the differences in maternal investment (via lactation) required to raise male and female calves have been demonstrated to influence the subsequent success and timing of conceptions. Studies of farmed red deer in Scotland also demonstrated that hinds on different levels of pasture nutrition during lactation exhibited significant differences in conception date, with earlier conceptions favouring hinds on higher levels of nutrition. There is a growing body of evidence from monitoring of farmed red deer in New Zealand that the interaction between lactation and hind body condition score (BCS)/ liveweight influences subsequent conception rate and date. Recent studies on pre-rut versus post-rut calf weaning practices demonstrated effects of lactation on hind BCS and liveweight, calf growth rates and hind conception dates. These studies highlight the need to better understand the "costs" of lactation on reproductive performance, particularly under conditions of nutritional constraints. Keywords: lactation, nutrition, red deer, reproduction
The role of plants containing secondary compounds in sustainable deer farming - a review
Authors: Hoskin S.O. , Barry T.N. , Wilson P.R.
Published: March 2021

The productivity and health of farmed deer is improved by substituting perennial ryegrass-based pasture with forages containing condensed tannins (CT) and/or sesquiterpene lactones. Benefits have included improved lactation, growth, trace element status, resilience to internal parasites and reductions in parasite larval development. Forages evaluated for deer include the forage legumes sulla and birdsfoot tref oil, which contain CT, and the herb chicory, which contains both CT and sesquiterpene lactones. Autumn grazing of weaner deer on chicory has shown growth can be increased whilst anthelmintic requirement reduced compared to grazing of perennial ryegrass/ white clover pasture. The importance of secondary compounds relative to other nutritive characteristics of alternative forage species, such as low fibre and highly digestible carbohydrate concentrations, have not been fully characterised, but they are likely to contribute to improved deer health. Unlike sheep and cattle, deer pr oduce salivary proteins that bind CT, allowing them to consume plants containing higher CT concentrations than sheep and cattle. The effect of CT upon the digestion and absorption of protein, which has been determined for other domestic ruminants, needs to be measured in deer fed forage diets, to establish if beneficial effects exist. In vitro work has shown direct inhibitory effects of CT and sesquiterpene lactones extracted from forages on deer internal parasite larvae. The faeces, rumen and abomasal fluid of deer grazing chicory also contained substances reducing the viability of parasite larvae. Alternative plant species such as chicory, birdsfoot trefoil and forage willows containing secondary compounds will play an important role in low chemical sustainable deer farming. Keywords: anthelmintic, Cichorium intybus,condensed tannins, forage, Hedysarum coronarium, internal parasites, protein, red deer