bluuebunny/crossref_metadata_2025 huggingface dataset:
'Grasslands Maku' lotus seed production - research and practice
Authors: Lancashire J.A. , Gomez J.S. , Mckellar A.
Published: March 2021

The development of successful seed production techniques for the recently released tetraploid cultivar of Lotus pedunculatus Cav. (syn: L. uliginosis Schk.; and L. major Scop. Sm.) 'Grasslands Maku' must take account of the distinctive agronomic characteristics of the cultivar. These include slow establishment, particularly in the cool season, slow recovery from defoliation, and poor competitive ability with white clover and other weeds in fertile soils. Spring sowings in cooler areas, a minimum of lenient grazings, and the use of low rates (0.5 to 1.0 kg/ha) of ethofumesate to control white clover in establishing stands are recommended. Although shattering of ripe pods can be reduced by careful harvesting techniques and cutting when 70 to 80% of the pods have turned brown, some loss of seed is inevitable. It is suggested that the cultivar should be grown as a specialist seed crop rather than as part of a dual-purpose grazing and seed-production enterprise. Key words: Seed production, 'Maku' Lotus Pedunculatus, lotus, ethofumesate, seed harvesting, Trifolium repens.
Research in white clover seed production
Authors: Clifford P.T.P.
Published: March 2021

White clover seed yields from crops derived from pure autumn broadcast sowings harvested in the first year after sowing were improved by increasing sowing rate from 3 to 6 kg/ha. On moisture-retentive soils or where irrigation was available, mid-November closings gave highest seed yields for crops derived from either spring undersowings of cereals or as ryegrass mixtures taken for ryegrass seed in the first year from sowing. Closing a month earlier gave similar yields if 30 cm rather than 15 cm row spacings were used. Harvest should be no later than one month from main flowering to reduce the numbers of seedheads lost. General management should aim to promote good primary stolon growth rates over the month prior to mid-December if high flowerhead densities are to be obtained. Therefore excessive grazing before closing and poor timing of herbicide spraying for grass control should be avoided. Keywords: Trifolium repens, seed production, plant density, closing date, pollination, seed harvesting, management.
Recent developments in seed production in Oregon, U.S.A.
Authors: Rolston M.P.
Published: March 2021

Developments in weed control include the use of activated carbon applied in bands to protect the emerging grass seed crop from soil-applied herbicides. "Weed-seed free" crops can be produced with this technique, especially when combined with chemical seedbed treatments. Novel techniques of herbicide usage, including the roller herbicide applicator, are being used for weed control. Field burning is important for disease control and techniques of smoke management are improving. Aerial inspections of seed crops by seed certification inspectors are faster and are considered to be as thorough as ground inspections. Seed growers can be classified as either high- or low-cost producers. Fixed costs show economies of scale until farm size reaches 250 to 300 ha. Operating costs are similar for all types of seed crops, with fertilizer, herbicides and machinery costs representing up to 50% of total costs. Key words: Herbage seed production, Oregon, activated carbon, field burning, aerial inspections.
Problems of amenity grass seed production in New Zealand
Authors: Corkill L. , Rumball W.
Published: March 2021

The problems of seed production of amenity grasses in New Zealand are considered from two aspects - (a) increasing seed potential by breeding; (b) achieving that potential by good management as practised in the Netherlands, (a) In terms of breeding, the strategies to increase seed yield depended to some degree on the species concerned. With browntop it was necessary to discard about two-thirds of the most promising genotypes because of poor heading, but the remaining genotypes flowered freely and in unison, and gave good seed yields. With fescue even the best original plants were sparsely heading, so direct selection for prolificacy has been needed. This was also carried out for perennial ryegrass, as well as selection of early-heading genotypes to avoid infection by stem rust. (b) It is suggested that areas for seed of amenity grasses in New Zealand should be used for seed production only rather than for both forage and seed as is the usual practice. Techniques used in the Netherlands could serve as guidelines to procedures. The implications of low seeding rates, good weed control, high fertilizer applications and minimum cutting or grazing in promoting strong individual plants capable of high seed yields are discussed. Keywords: Amenity grass, seed production, New Zealand, breeding, management, Netherlands, Agrostis tenuis, Festuca rubra, Lolium perenne
Seed production of new grass cultivar
Authors: Lancashire J.A. , Hampton J.G. , Gomez J.S.
Published: March 2021

Some aspects of the agronomy and seed production of four recently released Grasslands cultivars are described. Matua prairie grass sown at 10 to 15 kg/ha in 50-60 cm rows has produced over 3000 kg/ha of seed from two harvests in one season. The problem of head smut can be overcome by treating the seed with 1% by weight of benomyl, but techniques for treating large seed lots still have to be developed. Roa tall fescue sown at 2.2 kg/ha in 60 cm rows has produced over 1000 kg/ha of seed in the second season from sowing. Early defoliations should be very lenient or avoided altogether because the species is very slow to establish. Maru phalaris has produced over 800 kg/ha of seed in the absence of defoliation between sowing and harvesting. Although the cultivar may be less prone to seed shattering than older types, it is still very important to harvest at the correct time. Raki paspalum is a valuable grass for the northern areas of New Zealand, but ergot seriously restricts seed production, particularly in wetter years. The disease can probably be controlled within the crop by cultural and fungicidal methods, but it is very difficult to prevent reinfection from outside areas. The best prospect is to avoid the disease by growing Raki in suitable areas which have a reliable dry period each summer. Keywords: Seed production, Bromus willdenowii, Phalaris aquatica, Festuca arundinacea, Paspulum dilatatum, new grass cultivars.
Effects of grass suppression on legume abundance during two contrasting seasons on a summer-dry hill country site
Authors: Hepp C. , Valentine I. , Hodgson J. , Gillingham A.G. , Kemp P.D.
Published: March 2021

The low level of legumes in New Zealand hill pastoral systems is a recognized problem that is likely to affect sustainability. The relative importance of the factors that cause low legume abundance has not been sufficiently tested, especially on dry hill country. This paper reports the effects of grass suppression in two contrasting years in a summer-dry hill country site on the east coast of the North Island. Suppressing grass with haloxyfop herbicide (Gallant) in late autumn increased legume abundance by > 25% in both years, but the response patterns were strongly influenced by soil moisture status. Moist late spring and summer conditions produced 34% more legume growth in both Â± herbicide treatments. Residual effects of grass suppression favoured white clover over subterranean clover growth under moist seasonal conditions. The control of grass growth in these hill swards improved legume abundance, but the overriding factor affecting legume content in the pasture was the level of soil moisture. Key words: grass suppression, haloxyfop herbicide, hill country, legume abundance, soil moisture, subterranean clover, summer-dry, white clover
Dry matter accumulation and sheep grazing preference of six winter active annual legumes
Authors: Hyslop M.G. , Slay M.W.A. , Moffat C.A.
Published: March 2021

Winter active legumes are suited to the mild winter areas of New Zealand, where they provide high quality forage in late winter and early to mid-spring. Six winter active annual legumes, persian clover, balansa clover, sweet clover, hybrid serradella, subterranean clover, and Medicago truncatula, were sown in a randomised complete block design with four replicates. Their dry matter (DM) accumulation and grazing preference to young sheep were measured every 3-6 weeks from sowing on 6 April 2000 until 24 October 2000. Total ungrazed DM production ranged from 5 500 kg/ha (sweet clover) to 9 300 kg/ha (balansa clover) over this period. The seasonal pattern of growth varied significantly between species, as did hogget grazing preference, with persian, balansa, and subterranean clover most preferred. These six plant species are capable of producing large amounts of high quality dry matter, but at all grazings, preference was extreme (measured by the number of sheep preferring to graze any one of the species when given a choice of all six), which may indicate the limited usefulness of some species. Key words: accumulative yield, grazing preference, Medicago truncatula, Melilotus albus, Ornithopus sativus x compressus, seasonal growth, sheep, Trifolium balansae, Trifolium respinatum, Trifolium subterraneum, winter active legumes
Subterranean clover in North Canterbury sheep pastures
Authors: Costello Tom and Anne
Published: March 2021

The Hawarden basin is typified by dry, hot conditions over summer, which makes it difficult to retain ryegrass/white clover pastures on the lighter soils. These conditions have led to the introduction of better-adapted species such as the annual, subterranean clover. The mid-flowering cultivar 'Mt Barker' was first sown in the 1930s; then the earlyflowering 'Woogenellup' and late 'Tallarook' were used in the 1960s. The 'Mt Barker' type became dominant in these old pastures. The key factors for good subterranean clover growth were soil fertility (particularly P and S), space following dry summers for seedlings to re-establish, and moisture in the spring to maximise herbage yield. A visit to Australia in 1996 prompted the inclusion in new sowings of the late-flowering 'Leura' at high sowing rates (8-10 kg/ ha). It has taken 5 years for seed stocks to build to a level where we can identify good seedling strikes of 'Leura'. Two of the autumns over this period were very difficult and hindered normal establishment. Rainfall is erratic in North Canterbury, which affects the success of subterranean clover from one year to another. Dry summer conditions are optimal for subterranean clover strikes, as the pasture opens, and when the autumn break occurs, more than 2 000 subterranean clover seedlings/m2 can be produced. Autumn grazing management, when recovering from extreme drought, is critical because pasture must be spelled for 6 weeks to allow the subterranean clover to establish. However, if the autumn is wet, pasture cover must be controlled so that subterranean clover seedlings are not smothered. Set-stocking is best in spring to control pasture cover, but grazing should not be too hard during the flowering and seed set period. Subterranean clover seed yields of up to 250 kg/ha have been achieved from old pastures, but this is less seed than is produced under Australian conditions. Pasture renovation using the baker boot drill to re-introduce grasses and new cultivars of subterranean clover has been successful following very dry summers. Lamb growth rates have been excellent on subterranean clover-based pastures and these have increased the farm's meat production and reduced the cost of maintaining pastures. Key words: grazing management, North Canterbury, seedling establishment, seed set, subterranean clover
The effect of continuous grazing on the seed production of Subterranean clover (Trifolium subterraneum).
Authors: Smetham M.L. , Dear B.S.
Published: March 2021

Three pure swards of subterranean clover were either (a) left ungrazed with a leaf area index (LAI) of 4.6, or (b) continuously grazed leniently to leave 1 600 kg DM/ha herbage mass equivalent to an LAI of 1.0, or (c) hard grazed to leave 1 400 kg DM/ha herbage mass equivalent to an LAI of 0.6 throughout the flowering period. These swards yielded 1 250, 320 and 70 kg/ha of seed, respectively. One intensive sampling during the middle of flowering showed that seed yield was positively correlated with plant weight, leaf area per plant, and area per leaf, specific leaf area and leaf area ratio. Grazing reduced numbers of both inflorescences and burrs and hence seed yield. Whilst reduced leaf area and plant weight may have also been partly responsible, under hard grazing, only 58% of potential reproductive sites were occupied which suggests that grazing animals also reduced seed yield by consuming these. It is recommended that continuous grazing during flowering and seed maturation should be controlled to leave at least 1 600 kg DM/ha of residual herbage mass, equivalent to an LAI of 1.0, if adequate seed is to be produced to be ensure the establishment of a high producing sward in the following growing season. Key words: flowering, grazing, herbage mass, leaf area, seed production, Trifolium subterraneum
White clover cultivars developed for temperate regions of South America
Authors: Widdup Keith , Garcia Jaime , Amadeo Juan , Guillen Roque , Real Daniel
Published: March 2021

White clover is an important forage legume in temperate areas of South America but the common cultivars used are winter-active, profuse flowering types and only persist for 2-3 years due to frequent moisture stress and hot summer conditions. A breeding programme was initiated to develop new types for intensive dairy and extensive cattle grazed pastures. Wide scale screening and crossing of germplasm from international and local sources revealed the potential of Ladino and ladino x local cultivar material for use in intensive pastures with good soils and grazing management. Improved persistence was a major objective for the extensive pastures and ecotype material collected from local farms together with crosses involving ladino and SE USA ecotypes were the best combinations. Experimental selections were developed for the two target environments and evaluated in 'scope' trials at three contrasting sites to determine herbage production and persistence potential. A ladino x local cultivar selection with large leaves, high herbage yields, extended winter to summer growth and ability to persist for at least 3 years was released as the cultivar 'Goliath' for intensive dairy-type pastures. A local ecotype selection with medium leaf size, slower establishment but high stolon density aiding persistence, and high seed yields was released as the cultivar 'Aquiles' for use in extensive pastures
Increased cuticular wax accumulation and enhanced drought tolerance in transgenic alfalfa (Medicago sativa) by overexpression of a transcription factor gene
Authors: Zhang J.I.-Yi , Sledge Mary , Bouton Joseph , Wang Zeng-Y.U.
Published: March 2021

Plant cuticular waxes play an important role in protecting aerial organs from damage caused by multiple environmental stresses such as drought, cold, UV radiation, pathogen infection, and insect attack. We characterized a novel AP2 domain-containing transcription factor gene, designated WXP1, from the model legume plant Medicago truncatula. The gene is able to activate wax production and confer drought tolerance in alfalfa (Medicago sativa). The predicted protein of WXP1 has 371 aa; it is one of the longest peptides of all the single AP2 domain proteins in M. truncatula. Transcript level of WXP1 is inducible by cold, ABA and drought treatment in shoot tissues. Overexpression of WXP1 under the control of CaMV35S promoter led to a significant increase in cuticular wax loading on leaves of transgenic alfalfa. Transgenic leaves showed reduced water loss and chlorophyll leaching. Transgenic alfalfa plants with increased cuticular waxes showed enhanced drought tolerance demonstrated by delayed wilting after watering was ceased and quicker and better recovery when the dehydrated plants were re-watered.
Selecting white clover (Trifolium repens L.) for sheep and cattle grazing environments
Authors: Jahufer Zulfi , Ford John , Caradus John , Woodfield Derek
Published: March 2021

Adaptation to different grazing systems is an important attribute in white clover breeding. A set of 41 white clover breeding lines and nine commercial cultivars were evaluated under two grazing systems, sheep and cattle, in Manawatu. The objective was to identify lines with either specific or broad adaptation to these two different grazing systems. The trials were established in late autumn 1997 and completed in autumn 2000. Visual scores of clover yield for spring, summer, autumn and winter of year 2 and spring, summer and autumn of year 3 were analysed. There was significant (P
New developments in genotyping and phenotyping for breeding improved sustainability in temperate forage grasses
Authors: Donnison M.O. Humphreys , Turner M.W. Humphreys , Wilkins SkÃ¸t , Yadav R.
Published: March 2021

New genes for 'sustainability' traits are being incorporated into ryegrass (Lolium sp.) breeding populations using marker-assisted intra- and inter- specific introgession from a wide range of genetic resources. Mapping families, substitution and introgression lines have been produced to facilitate gene transfer between Festuca and Lolium species. Advanced metabolomic phenotyping techniques (e.g. NIRS and FT-IR) can help close genotype-phenotype gaps to increase the environmental sustainability of grassland and improve the nutritional value of genotypes for forage or their chemical suitability for biofermentation/biofuel.
Pastoral Genomics - a foray into the clover genome
Authors: Jones Chris , Williams Warren , Hancock Kerry , Ellison Nick , Scott Alicia , Collette Vern , Jahufer Zulfi , Richardson Kim , Hay Mike , Rasmussen Susanne , Jones Craigh , Griffiths Andrew
Published: March 2021

Pastoral Genomics is engaged in applying molecular mapping and functional genomics to characterise and manipulate key phenotypic traits associated with improved productivity in the commercially important forage crop white clover (Trifolium repens L.). We report on the development of a framework linkage map for white clover and the application of this map to the identification of quantitative trait loci (QTL) associated with vegetative and seed yield traits. Homologues of genes responsible for the traits of interest have been identified and cloned in order to identify 'perfect markers' for marker assisted breeding and to develop a cisgenicÂ® clover cultivar. We introduce western clover (T. occidentale), a diploid perennial clover species closely related to white clover, as a stoloniferous clover model to dissect low heritability traits initially intractable in white clover. We have identified extensive genetic variation in this species, which previously has been reported to be remarkably uniform. We have developed a framework map for T. occidentale and demonstrated conservation of marker order and spacing with white clover. An ethyl methane sulfonate (EMS) mutant population has been used to isolate three distinct groups of condensed tannin (CT) mutants. We have also investigated our model's transformation potential, achieving frequencies 2-3 fold higher than for white clover and suggest that this model is potentially useful for genomic analysis of white clover and other clonal species
The Noble Foundation hardinggrass (Phalaris aquatica) breeding program
Authors: Hopkins Andy , Saha Malay , Zhou Lili
Published: March 2021

Hardinggrass has the potential to provide grazing during the fall to spring months in the south central USA. Here we describe a breeding program focused on developing improved hardinggrass cultivars for this region. More than 300 accessions were evaluated for persistence under heavy grazing in Oklahoma. The most promising of these accessions were evaluated for genetic diversity using AFLP markers. Accessions clustered closely in agreement with geographic origins with populations from Morocco representing a potentially novel source of germplasm. Two distinct breeding populations were constructed using this information. Additional populations, constructed using recurrent selection for survival under heavy grazing, have shown significantly greater persistence than currently available cultivars including 'Grasslands Maru'. Research is underway to develop high throughput methods to profile alkaloid composition and concentration in hardinggrass. These methods will be applied to determine genotype and genotype x environment effects on alkaloid composition of elite breeding populations and commercial cultivars. Results of these evaluations, along with animal safety trials, will be critical in determining which populations to release as improved hardinggrass cultivars for the south central USA.
Improvement of seed yield potential in tall fescue
Authors: Rolston M.P. , Easton H.S. , Archie K.H. Widdup , Lyons T.B.
Published: March 2021

Modest and unreliable seed yield limits the usefulness of some forage tall fescue cultivars. In preliminary experiments, significant correlations for seed weight per panicle but not panicle number were established between spaced plants and sown rows of half-sib progeny derived from them. However, seed yield of the sown rows in the second year was not correlated with first year values. Half-sibling families of an elite breeding pool were sown in rows at three contrasting sites in autumn 1999. The following spring, panicle numbers were counted and in summer seed was harvested and weight per panicle calculated. Families varied significantly for seed yield and yield components, and family values were correlated between sites. Seedlings were raised from remnant seed of the best performing families (based on first year data at the 3 sites) and assessed pre-anthesis for panicle number. Selected plants were isolated and seed harvested. After progeny tests, three sub-sets of elite plants were isolated to produce improved selections. Plot trials sown at Lincoln (New Zealand) and at Pergamino (Argentina), showed significant seed yield improvements from the selections compared with "Grasslands Advance," a standard cultivar derived from the same breeding pool
A quantitative trait locus analysis of seed production traits in perennial ryegrass (Lolium perenne L.)
Authors: Matthew Sartie , Faville M.J.
Published: March 2021

A full-sib mapping population (n=188) from a cross between cultivars 'Grasslands Impact' and 'Grasslands Samson' was used to identify quantitative trait loci (QTL) controlling seed yield and component traits in perennial ryegrass. Thirteen traits, including seed yield per plant (SYP) and five seed yield components (number of spikes (SP), spikelets per spike (SS), florets per spikelet (FSP), seed weight (SW) and floret site utilisation (FSU)), seed yield per spike (SYH) and seven other seed yield-associated traits, were phenotypically assessed in a replicated spaced plant field experiment. Interval mapping identified 35 QTL for all traits but one, spanning all linkage groups (LG). Multiple QTL were detected for most traits. QTL for SYP and component traits, as well as some seed yield-associated traits, co-located to the same genomic regions on LG 1, 2 and 6. Markers associated with these regions, in particular, will form the basis for the on-going development of MAS tools for improvement of seed yield and quality in breeding programmes. Further development will require refinement of QTL positions and effects using multiple QTL mapping (MQM), and validation of QTL and associated markers in other genetic backgrounds and environments
Genetic variation in perennial ryegrass for root profile characteristics
Authors: Crush J.R. , Easton H.S. , Waller J.E.
Published: March 2021

Fifteen plants, replicated twice, of each of 20 half-sib families of perennial ryegrass were grown in deep sand tubes irrigated with a low ionic strength nutrient solution in a glasshouse. Top growth was measured. Roots were turned out, cut into 10 cm profile increments, washed free of sand, dried and weighed. For top growth, total root growth and root-shoot ratio, there were significant differences among families translating to narrow sense heritability coefficients between 0.3 and 0.4. However, the ratio between root in the top 10 cm and total root, and a parameter for a well-fitting exponential model describing root profile showed variation between individuals but very little or no variation between families. This translated to narrow sense heritability coefficients of less than 0.1.
Genetic origins of perennial ryegrass (Lolium perenne) for New Zealand pastures
Authors: Stewart Alan
Published: March 2021

New Zealand perennial ryegrass germplasm originated largely from seed introduced from the UK during the 1800s. Modern breeding began in the 1930s and soon utilised selections from the best ecotypes as "mother" seed for the seed industry and after numerous reselections this resulted in the release of Grasslands Ruanui 1955. Winter growth was improved by hybridising with Italian ryegrass to produce the "short rotation hybrid" cultivar Grasslands Manawa, released in 1943. Further introgression to perennial ryegrass led to the development of Grasslands Ariki "long rotation hybrid", functionally a perennial, released in 1965. The identification of a valuable ecotype from the Mangere district in Northern New Zealand in the late 1960s had a substantial impact on ryegrass breeding in New Zealand and has subsequently been widely used in all Australasian ryegrass breeding programs. Germplasm from mild oceanic regions of North West Spain, collected in the 1980s, has provided a valuable combination of winter growth with late flowering behaviour. This has been used in many recent breeding programs. Considerable research has gone into endophytes of ryegrass to develop safe and persistent pastures. The lack of chemical diversity within endophytes of New Zealand ecotypes has required considerable sourcing of overseas germplasm for endophyte discovery. In recent years breeders have introgressed a wider range of germplasm, including winter active Mediterranean material, cold tolerant Northern European material, as well as Italian ryegrass and meadow fescue. Tetraploid perennial ryegrass cultivars have been released in the last 20 years, based largely on New Zealand diploid cultivars but also using some European tetraploids. Today a full range of cultivars from early flowering diploids to late flowering tetraploids is available to the farming industry. The use of a wider range of germplasm is discussed in relation to advances in our knowledge of genetic origins of perennial ryegrass. Genetic advances should be achievable from more diverse germplasm by using a combination of traditional breeding techniques and new technologies, such as marker assisted selection. However, lifting overall pasture performance still remains a challenge as ryegrass cultivars are used in mixtures with white clover and any increase in the ryegrass yield is often partially cancelled by decreased clover yields
Added-value products: healthier milk from forage, scope for breeders?
Authors: Elgersma Anjo , Smit Harm , Taweel Hassan , Witkowska Izabela
Published: March 2021

Plant lipids are a major source of beneficial fatty acids (FA) in milk. Forage quality differences can affect rumen metabolism and there could be opportunities to change the composition of ruminant products through species or cultivar choice. Twelve dairy cows were used in two stall-feeding trials with fresh grass to evaluate the effect of diploid perennial ryegrass (Lolium perenne) cultivars on milk FA composition during the growing season. Six cultivars were cut daily during three 14-day periods at the same target yield. The experiments consisted of two 3x3 Latin square trials, in each of which 3 cultivars were fed to 2 groups of three cows. The six cultivars differed significantly in concentrations of water-soluble carbohydrates, neutral-detergent fibre and crude protein. However, there were no significant differences among the six cultivars in FA concentration or proportions of FA. No variation in DM intake, milk production and composition or milk FA composition was found. The latter may be due to the lack of variation in grass FA concentration and composition in the cultivars studied.
Can pasture persistence be improved through the use of nonryegrass species?
Authors: Milne G.D.
Published: March 2021

Recent discussion about pasture persistence concentrates on pastures based on perennial ryegrass, the most commonly used grass species. This paper raises the question as to whether some of the causes of poor pasture persistence are due to perennial ryegrass being used in environments to which it is not suited. The adaptation to environmental stresses, particularly water, temperature and nutrient deficiencies, in different regions of New Zealand of tall fescue, cocksfoot, phalaris, and lucerne are discussed, and how this impacts on persistence advantages over perennial ryegrass. Keywords: persistence, pasture, Dactylis glomerata, Festuca arundinacea, Lolium perenne, Medicago sativa, Phalaris aquatica
An evaluation of wild populations of perennial ryegrass from dairy farms in the Waikato and Bay of Plenty districts
Authors: Ryan D. , Cooper B.M.
Published: March 2021

A ryegrass breeding programme to improve the seasonal growth and plant persistence of perennial and hybrid ryegrasses in the Waikato began at AgResearch Ruakura, Hamilton in 2001. One approach was to characterise the genetic diversity of the naturalised populations within 26 dairy farms from different districts around the Waikato and Bay of Plenty (BOP) regions. Plants from 26 individual breeding lines were evaluated as single spaced plants over a 3-year period in comparison with three commercialised ryegrass cultivars. Principal Component Analysis was used to order the plant populations in accordance with the observed plant variables of seasonal growth pattern, tillering ability, leaf size and extension, and the incidence of crown rust. A hierarchical cluster analysis of the wild populations revealed two distinct plant groups. A mix of large leaf Italian Lolium multiflorum and hybrid plants were typical from the warmer drier areas of the BOP. The Italian ryegrass was prone to severe crown rust infection whereas the hybrids were more resistant. Shorter, narrow leaved and densely tillered plants with a high rust infection dominated the Waikato populations. Ecotypes that maintained high plant tiller density throughout the seasons had the best persistence. Plants that displayed an improvement in seasonal yield and tillering over the commercial cultivars were considered an important genetic source to develop new persistent cultivars for the Waikato and BOP regions. Keywords crown rust, drought, ecotypes, Lolium spp., plant breeding
Managing sheep and beef farm systems - where does pasture persistence fit in?
Authors: Stevens D.R.
Published: March 2021

Pasture persistence is highly rated by sheep and beef farmers as an important factor determining wholefarm performance. Managing pastures to ensure the persistence of newly sown pasture species must be considered as a part of the decision making process of the whole farm. The farmer aims to optimise the outcomes of resource use over time, rather than maximise any single resource, and therefore grazing decisions must be considered in this context. Pasture renewal is a major event-driven disruption that replaces current pasture species with competitive species, creating a grass-legume complex that has a tendency to develop towards a community of plants that tolerate the local environmental stress. Pasture persistence can be improved through managing the impacts of and interactions between environmental stressors on the pasture. Interactions between pasture management options, such as grazing and fertiliser, and the major environmental stressors of soil moisture, temperature, soil fertility, grazing and pests are discussed. Keywords: ecology, environmental stressors, farm systems, grazing management, pasture persistence.
Changes in pastoral farming practices and pasture persistence - a review
Authors: Clark D.A.
Published: March 2021

From 1990 to 2010 there have been major changes in New Zealand pastoral agriculture. The intensification of the dairy industry has led to higher stocking rates, lower grazing residual DM, higher N fertiliser use and increased supplementation. However, there is little evidence that these changes are responsible for the decreased persistence of ryegrass-based pastures, rather the interactions between low summer rainfall, low water-holding capacity soils, endophyte status and cultivar 'type' have caused significant pasture damage. These factors, together with plant nutrient status (especially N) and plant population survival mechanisms (tiller dormancy, birth and death rates, seed production and establishment) are hypothesised to be the primary drivers of ryegrass persistence. A secondary subset of pests, diseases, weeds and high grazing intensity (pugging and pasture 'pulling') are considered to interact with the primary drivers to compromise ryegrass tiller survival. Attention to plant species and cultivar selection, tiller replacement mechanisms and ryegrass cultivar development are required to improve ryegrass persistence. Keywords: climate, dairy, N fertiliser, perennial ryegrass, white clover
Effect of defoliation strategies on the productivity, population and morphology of plantain (Plantago lanceolata)
Authors: Ayala W. , Barrios E. , Bermudez R. , SerrÃ³n N.
Published: March 2021

This trial provided information about effects of defoliation frequency, defoliation intensity and winter management (grazing or rest) on the productivity, morphology and plant population of a 3-year-old plantain (Plantago lanceolata) stand. Plant population density declined drastically over time independently of grazing management, with the greatest decrease in summer. Winter grazing had a critical effect on the productivity and population remaining 6 months later. Frequent grazing during summer increased plantain contribution. Grazing intensity reduced crown weight and diameter of individual plants. Further studies are required to determine the interactions of defoliation management with pastures of different age including the natural reseeding as a mechanism to maintain plant recruitment. Keywords: defoliation, grazing, morphology, population
CONTAMINATION OF WHITE CLOVER SEED CROPS BY BURIED SEEDS
Authors: Lancashire J. A. , Ralston M.P. , Scott D.J.
Published: March 2021

Thirty five certified seed lines of 'Grasslands Pitau' white clover produced under OECD rules showed marked variations in growth and morphological characteristics according to their region of origin. Of lines grown in Oamaru district, South Canterbury, 90% were significantly different from a Pitau breeders (pre-basic) line in winter growth scores, leaf size and picric acid scores. 90% of lines grown in Marlborough were similar to a Pitau breeders line. Buried white clover seed counts were 260/m' (2 kg/ha) in Marlborough and 1060/m (7.5 kg/ha) in Oamaru. Plants grown from buried seed collected in Canterbury generally had smaller leaves, less winter growth and lower picric acid scores than Pitau. The additional possibility that natural selection of genotypes occurred because some crops of Pitau have been grown under climates and/or managements to which it is not adapted, is also discussed. Preliminary studies of 43 commercial lines of 15 cultivars from 4 countries grown outside New Zealand indicated that 3540% showed significant differences in winter growth and leaf size between lines of the same cultivar. New Zealand grown commercial lines of Huia obtained overseas showed good uniformity. It appears that there is a world-wide problem of genetic contamination in white clover cultivars. High buried seed loads are a potential long term source of contamination which is being exaggerated by the increasing numbers of cultivars. New Zealand has already moved to implement tighter certification standards than those recommended by OECD. Keywords: Trifolium repens, 'Grasslands Pitau', buried seed, seed certification, OECD, genetic contamination.
EFFECT OF LEAF AREA ON WHITE CLOVER SEED PRODUCTION
Authors: Clifford P.T.P.
Published: March 2021

Leaf size is a major determinant of white clover seed yield. A three-fold increase in leaf size halves seed yield. From a survey of commercial crops, an optimum leaf size concept was used to explain the reduction in yield potential for extremes in leaf size. Overgrazing gave small leaves and lowered seed yields. Closing too early gave large leaves and lowered yields. With good management, optimum leaf size was the smallest size possible, consistent with ensuring an adequate bulk for efficient harvesting. A healthy highly-reproductive stolen population has to be developed before closing. Secondly, moisture regulation over the crop season, preventing excess watering to minimise plant exploitation of surplus fertility, reduces the potential for large leaves to develop. Mid-November closing coupled with maintaining soil moisture at about 25% plant available, over flowering, are sound management practices. Amongst cultivars, differences in seed yield potential may also be related to leaf size. In general the larger the mean cultivar leaf size the lower the seed yield. Keywords: Trifolium repens, white clover, seed production, leaf size, soil fertiity, moisture, management options.
Marketing herbage seeds
Authors: Smith R.G. , Mather R.D.J.
Published: March 2021

One of the most underrated factors in our pastoral development has been the humble seed. Rarely recognised, it has made a significant contribution in allowing farmers to increase production within the wide range of climatic and fertility environments encountered in our country. But now, the quality of New Zealand pastures is becoming internationally recognised and has been one of the main contributing factors in the development of our country, together with the drive and competence of our farming fraternity and the abundant use of fertiliser.
Agronomic and environmental constraints in North Island dairying and the choice of pasture species
Authors: Goold G.J. , Thomson N.A. , Duder F.R.
Published: March 2021

Traditionally dairy production in New Zealand has been centred on regions with adequate rainfall and free draining, fertile soils. Within such regions however, considerable variation between properties is observed in the level of dairy production, often attributed to differences in animal management skills. In contrast, the authors of this paper believe that there are important agronomic and environmental constraints to high dairy production and the paper considers, in particular, the role which various pasture species and cultivars can play, in alleviating these constraints.
Limitations to pasture production and choice of species
Authors: Scott D. , Keoghan J.M. , Cossens G.G. , Maunsell L.A. , Floate M.J.S. , Wills B.J. , Douglas G.
Published: March 2021

The South Island hill and high country is defined as those areas which were in natural grassland at the time of early European settlement. This includes the major geographical regions of dry hill and high country of Marlborough, Canterbury and North Otago, and the wet acid tussock grasslands of Otago and Southland. To define the most appropriate pasture species for farming in these areas, it is first necessary to define the appropriate environmental factors since they largely determine the types of farming systems possible. Once this has been done, it will be found that there are only one or two pasture species which are the best option in each environment or farming system.
Summary
Authors: Anon A.
Published: March 2021

Good planning well in advance of the need is the key to successful pasture systems. Each system must be individualised in accordance with the particular farm enterprise. Species and cultivars must be selected according to their likely management use (and abuse), as well as their soil and climate suitability. High country properties are commonly run as large, set stocked paddocks. This should be regarded as an accident of history rather than a desirable situation.
PRAIRIE GRASS
Authors: Brown I.R. , Hampton J.G. , Lill C.
Published: March 2021

Prairie grass is used in dairy pastures and for winter/spring feed on sheep farms. Four. hundred and fifty-nine hectares of prairie grass were grown for seed in 1987/88. Average yields are 680 kg ha-'; the specialist grower can achieve yields of 1400 kg ha-'.
White clover or nitrogen fertiliser for dairying?
Authors: Clark D.A. , Harris S.L.
Published: March 2021

Annual production in New Zealand dairy pastures is limited by nitrogen supply and therefore requires nitrogen fertiliser to increase annual pasture production. This paper summarises the advantages and disadvantages of clover nitrogen and fertiliser nitrogen including the effects of both nitrogen sources on feed quantity and quality, factors limiting nitrogen fixation and nitrogen fertiliser response, defoliation effects on white clover (Trifolium repens L.), animal health problems associated with clover and nitrogen fertiliser, and environmental effects. UDDER, a dairy farm simulation model, is used to predict the nitrogen fertiliser rate and white clover content in pasture necessary for optimum pasture production and feed quality. Maximum gross margins per ha and a high level of milksolids production per ha and per cow can be best achieved by combining nitrogen inputs from white clover and nitrogen fertiliser. The model predicts best results would be achieved with clover contents of 30-40% and nitrogen fertiliser rates of 100-200kgN/ha/yr. Keywords: dairying, feed quality, nitrogen fertiliser, nitrogen fixation, Trifolium repens
Inheritance and expression of transgenes in white clover
Authors: Scott Alicia , Woodfield D.R. , Allan Anne , Maher Dorothy , White D.W.R.
Published: March 2021

White clover plants from a range of cultivars can now be routinely transformed with cloned foreign genes. However, before transgenic white clover cultivars can be developed, these inserted genes must be stably inherited and expressed at appropriate levels in progeny. Primary transgenic white clover plants containing a uidA (GUS) reporter transgene were outcrossed and the inheritance and expression of the uidA gene was examined over two generations, in several different cultivar backgrounds. Both Mendelian inheritance and consistent expression in different genetic backgrounds were obtained from strongly expressing primary transgenic plants. However, primary transgenic plants with weak or variable expression gave non-Mendelian inheritance and inconsistent expression of the transgene in progeny plants. Transgenic BC1 plants were also intercrossed to produce a segregating F2 population containing individuals heterozygous or homozygous for the transgene. In these populations heterozygous and homozygous plants had similar levels of uidA gene expression. These results indicate that F2 plants, homozygous for a transgene, might be used to develop a transgenic cultivar. However, both selection of a primary transgenic plant with stable, high level expression of the introduced gene and progeny testing, to determine the influence of genetic background, are prerequisites to such a development. Keywords: gene expression, inheritance, transgene, uidA reporter, white clover
Third generation progress in breeding white clover for resistance to root-knot nematode
Authors: Van den Bosch J. , Mercer C.F.
Published: March 2021

Root-knot nematode (Meloidogyne sp.) reduces growth and nutrition of white clover (Trifolium repens L.) in New Zealand, and breeding resistant cultivars (with low galls per gram of root) is the preferred control method. Resistant and susceptible selections were bred from a wide range of white clover lines for three generations. In the third generation there were significant differences between seed lines from the selections for number of galls, root dry weight, visual growth score and galls/gram of root dry weight. Resistant selections had 43% of the susceptible selections' galls per gram, and 50% of the number of galls. Germplasm showing resistance to Meloidogyne spp. in the USA showed partial resistance to the local Meloidogyne sp. Two resistant and two susceptible genotypes were also compared for nematode egg production; resistant genotypes had a mean of 3,460 eggs/plant, compared to 25,030 for susceptible genotypes. Keywords: breeding, Meloidogyne sp., resistance, rootknot nematode, screening, selection, Trifolium repens, white clover
Influence of grazing management and drought on white clover population performance and genotypic frequency
Authors: Brock J.L. , Caradus J.R.
Published: March 2021

Between 1984 and 1990, the performance of 'Tahora', 'Huia', 'Pitau' and 'Kopu' white clover cultivars were evaluated in self-contained farmlets under rotational grazing and set stocking with sheep. A severe late spring-early summer drought in the third year from sowing (1986-87), caused a marked interaction between grazing management and cultivar performance. The drought caused no losses under set stocking, but large losses of stolon (75-90%) and a reduction in white clover content from 15% to 2% under rotational grazing. All cultivars were equally affected and recovery over the next 3 years was slow, although the small-leaved Tahora recovered faster than the large-leaved Pitau and Kopu. It was hypothesised that this would have caused differences in the preferential loss of genotypes with specific characteristics between grazing managements. Populations of white clover sampled from the field in 1989 and established from the original seedlines, were grown in common conditions for a year and compared for leaf size and cyanogenesis content. There had been a significant loss in mean leaf size in all cultivars with time, irrespective of drought or grazing management. It was shown that a general decline in stolon biomass commenced in all treatments 18 months after sowing, suggesting either, (1) a preferential loss of large-leaved genotypes with time irrespective of grazing management, or (2), a general change in per-formance of all genotypes, which may coincide with the change from dependence on seminal taproot of the seedling, to nodal rooting on free growing stolons. Keywords: cultivars, drought, genotypic change, grazing management, populations, Trifolium repens, white clover
Cultivar development and links to industry
Authors: Hay R.J.M. , Lancashire J.A.
Published: March 2021

A brief history of how DSIR Grasslands operated as a plant breeding institute for New Zealand pastoral farming is presented, and this perspective shows how the present situation has been shaped whereby cultivars are now developed under contract to the forage division of AgResearch. A hypothetical cultivar development programme is detailed to show the mechanics of the Cultivar Development and Maintenance Unit (CDMU) operation. The role of CDMU in the future is discussed along with the continuing pressure for white clover seed production area in Canterbury. Keywords: buried seed, CDMU, cultivar development, plant variety rights, seed industry
Maximising seed production potential in white clover: factors influencing seed set per floret
Authors: Thomas R.G.
Published: March 2021

The causes of low seed set per floret in white clover (Trifolium repens L.) are reviewed. Three stages of flower head development are distinguished as important for a high level of seed set: a pre-fertilisation stage, a stage of anthesis leading to pollination, and a postfertilisation stage in which seed provisioning occurs. In sunny conditions the percentage seed set is limited at the pre-fertilisation stage by up to 20-30% ovule sterility. Relatively low light intensities during the postfertilisation stage can lead to abortion of a high proportion of fertilised ovules and developing seeds. Experimental results suggest that seed yields under optimal growing conditions can be limited solely by the level of pre-fertilisation ovule sterility and probably cannot be bettered, but further understanding of the seed-provisioning requirements for photosynthate could lead to improved management practices for seed production under conditions of lower light intensities. Keywords: abortion, light intensity, ovule, seed provisioning, sterility, white clover