A community investigation into the use of cover crops to improve soil health and decrease the leaching of nitrates to ground water
A.J. CARTER
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Intensive land use systems such as market gardening
have long been recognised for their often deleterious
effects on soil and water. In an area of North Otago
a community land care group, known as the North
Otago Volcanic Soils Environmental Group
(NOVsEG), is concerned about the impacts that
past and present management practices have had
on the Waiareka soil. A previous study, initiated
by the Otago Regional Council, which looked at
the environmental impacts of intensive horticultural
land use in this area, highlighted that soil organic
matter levels were decreasing and that nitrate levels
in the groundwater were increasing. To address
these issues, NOVsEG set up a trial to investigate
the benefits of cover crops as opposed to the current
fallow ground practices. The trial compared five
different cover crops and resulted in the
identification of best management practices for
incorporating cover crops into a crop rotation.
Through the group’s initiatives, information
collected on the advantages and disadvantages of
each cover crop will now provide the market
gardeners with practical options for maintaining
soil organic matter and decreasing nitrate leaching
into groundwater.
Keywords: community investigation, cover crops,
leaching, market gardening, nitrate, North Otago
Volcanic Soils Environmental Group (NOVsEG),
soil health
Adoption of forage technologies by New Zealand farmers – case
studies
John Caradus, Simon Lovatt and Bruce Belgrave
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The large majority of New Zealand’s NZ$21.1 billion in
agriculture exports for the 2012 calendar year (adding
together meat, wool, dairy, livestock and processed
agricultural export) is derived from animals that consume
pasture, despite recent increases in the amount of
supplementary feeding. Such reliance on pasture
production has resulted in farmers continuing to seek
technologies that improve both production and pasture
persistence. New Zealand farmers have been rapid adopters
of new forage technologies, such as the herb chicory, and
novel endophytes that have been shown to improve
perennial ryegrass persistence and reduced animal health
problems. Plant breeders have also attempted to achieve the
compromise of high production and good persistence in
important species such as white clover. This paper attempts
to show how important these developments have been and
how willing farmers have been to adopt them into their
farming systems.
Avanex™ Unique Endophyte Technology - Bird deterrent
endophytic grass for amenity turf and airports
Christopher G L Pennell and M Philip Rolston
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Bird strike is recognised throughout the civil and military aviation industries as a significant cost
with more than $US 2 billion/year attributed to this problem globally. To manage this risk the aviation
industries have in the past adopted many practices to frighten wildlife from airports rather than reducing the
attractiveness of the area by grass habitat management. There has been little proven research on ground cover
species evaluation using fungal endophyte to reduce wildlife. Our research has shown that the adoption of a
specialist Neotyphodium fungal endophyte (strain AR601) placed in a turf type tall fescue cv. Jackal (Festuca
arundinacea Schreb.), is reducing bird numbers and strike rates on the test airfields under study. In the
recreational industry, large birds such as Canada geese (Branta canadensis), which forage on tender new
shoots and stems, can cause severe damage to turf with the added issue of faecal contamination and associated
heath issues. The inoculation of another specialist endophyte (strain AR95) into a turf type ryegrass (Lolium
perenne L.) cv. Colosseum offers another tool to reduce this problem. This paper reviews the results from
trials of these selected turf type grasses containing the unique fungal endophytes and shows effects on
herbivorous, insectivorous and omnivorous birds that visit airfields and surrounding parklands for foraging.
Specialty endophyte grasses may also have a place in the viticulture and horticulture industries to reduce the
use of insecticides. Extracts and mulches offer a new opportunity to use grass endophyte associations.
Balancing pastoral and plantation forestry options in New
Zealand and the role of agroforestry
Grant B Douglas, Andrew J Wall, Michael B Dodd, Martin F Hawke and Ian R
McIvor
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Abstract. Pastoral agriculture and forestry enterprises are key features of New Zealand’s landscape and are
very important economically. They are competing landuses, particularly on moderate to steep hill country.
Agroforestry involving spaced trees of Pinus radiata on pasture was developed in the 1970s to provide dual
incomes from livestock enterprises and the later tree crop. In contrast, wide-spaced trees of predominantly
Populus and Salix spp. are planted mainly for erosion control. Characteristics of pastoralism and plantation
forestry are reviewed, including trends in conversions between these landuses. Roles, challenges and opportunities
with wide-spaced trees are presented, together with current and future research initiatives. Pastoralism
and forestry will continue to compete strongly for hill country sites and at present there is an increasing trend
of converting previously forested areas to pasture, particularly in the central North Island. Agroforestry involving
Pinus radiata has virtually ceased because of adverse effects on wood quality, pasture production and
animal performance. There are millions of wide-spaced trees of Populus and Salix spp. on hill country and
their planting is expected to continue unabated because they are the most practical and efficient means of
enabling pastoralism on erodible slopes and they provide multiple ecosystem services. The species have significant
advantages compared to other woody species but many older trees have grown very large because
they have received negligible or no silviculture. This is an increasing problem, requiring development and
implementation of appropriate management strategies. There is growing interest by landowners in the environmental
outcomes of spaced-tree plantings.
BREEDING FOR RESISTANCE TO RYEGRASS STAGGERS,
THE INFLATION-PROOF LONG-TERM SOLUTION?
R.L.HEWETT
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Ryegrass staggers is by far the most serious animal health problem on our
property at Cheviot, where we operate an all-grass system wintering 1500 stock
units, almost entirely sheep. In the season just past, stock losses from staggers
were about equal to those from all other causes combined including new-born
lambs. Direct costs of the disease were calculated at $7 per stock unit, with additional
meat and wool production losses amounting to at least $3 per stock unit.
The problem is severe through the North Canterbury district, affecting in
particular the more highlydeveloped and intensively-stocked farms with highproducing
pastures. Moreover, its severity is steadily increasing as the content
of weeds and native grasses in the sward decreases on developing farms, a trend
of some importance to all involved in improvement of our grasslands.
Case studies which demonstrate the financial viability of
precision dairy farming
Ian Yule A, Hayden Lawrence B, Craige Mackenzie C, Carolyn Hedley D, Miles Grafton E
and Reddy Pullanagari
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A number of case studies are used to demonstrate the financial viability of precision farming
methods for intensively managed pastures. Precision farming has sometimes been criticized as being
technology-led where the management goals and desired outcomes are sometimes poorly defined. Case
studies presented in this paper demonstrate a strong management approach where appropriate
technologies are selected to contribute to the financial success of the farm. The first case study farm has
increased milk production by 70% in four years, increased pasture production by 43%, reduced fertilizer
costs to 43% of previous levels and has successfully predicted annual production to within 2 to 3% of
actual. A strong emphasis on performance measurement is used to support a four stage management
approach which consists of Planning, Measurement, Management and Review. The measurement systems
in place inform the management at both strategic and operational levels and include twice daily recording
of individual milk production and cow weight. The electronic identification (EID) system has been in
place since 1996. The second case study farm has demonstrated similar savings in base fertiliser
utilisation but has utilised other additional precision agriculture technologies such as the use of crop
sensors and variable rate application of nutrients. Again a strong management focus is given, this time
expressed as measure, manage, mitigate. This farming partnership also has a very strong environmental
sustainability focus and recently received national recognition as the Supreme Winner of the 2013 New
Zealand Ballance Farm Environmental Awards, giving further validation to the idea that precision
agriculture is profitable as well as environmentally sustainable. Craige Mackenzie has also invested in
precision irrigation, and there is a growing body of evidence to suggest that this method can give
significant economic and environmental benefits on intensively managed pastures. Further case studies
presenting the advantage of variable rate irrigation are also presented.
Keywords: Precision farming, pastures, dairy farming, fertiliser utilisation.
Cultural bastions, farm optimisation and tribal agriculture in
Aotearoa (New Zealand)
Tanira Kingi
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This paper outlines the influence of cultural factors (including tradition knowledge systems) on
tribal agricultural organisations in Aotearoa-New Zealand (NZ); and then presents a conceptual framework
that integrates several existing models and tools designed specifically for Maori farmer collectives.
Developing frameworks to assess impacts of multiple drivers of
change on grassland system
ME Wedderburn, Oscar Montes de Oca and Francisco Dieguez
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Grassland systems face many simultaneous pressures including market and policy compliance that
operate from local to global scale. The ability to adapt to these pressures against a background of constrained
natural resources and inputs is vital to the continued success of the grassland livestock industry and all those
dependent on its outputs. New Zealand and Uruguay collaborators have been developing a suite of tools and
processes embedded in an “innovation platform” to enable farmers, agribusiness and policy planners to
engage and collectively learn about the impact of their interacting individual decisions and strategies. We
describe the generic framework and demonstrate examples of the tools and processes used and their
applicability across scale in both New Zealand and Uruguay.
Keywords: Grassland systems, collective learning, social-ecological systems, strategic planning.
Development of a forage evaluation system for perennial ryegrass cultivar
and endophyte combinations in New Zealand dairy systems
Jeremy R. Bryant, David F Chapman, Elizabeth Leonard, William H McMillan, Graham A
Kerr, Glenn Judson, Tim Cookson and Grant R Edwards
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An economic index for perennial ryegrass (Lolium perenne
L.) cultivars is a relatively new concept, although recently
introduced in Ireland (McEvoy et al. 2011). By contrast, in
dairy cattle breeding, the concept of an economic index
rating animals and economic values underlying that index
is well entrenched (Philipson et al. 1994; Veerkamp, 1998).
Historically, forage evaluation data for individual cultivars
were either displayed using absolute numbers for seasonal
dry matter production within a season or across all seasons
with a notation to indicate statistical differences, or percentage
values where a reference cultivar is 100. The adoption
of an economic index and routine evaluation approach for
perennial ryegrass provides a method to identify traits of
economic importance to focus plant breeding efforts better
and to provide clarity for farmers around predicting cultivars
that will maximise farm profit. It also allows for
routine tracking of genetic gain of individual traits and the
economic index. In this paper, the economic based forage
evaluation techniques now used in New Zealand for perennial
ryegrass cultivar/endophyte combinations are presented.
Dissecting drought-response strategies of perennial ryegrass (Lolium
perenne L.)
Jean-Hugues B. Hatier, Lulu He, Marty J. Faville, Micheal J. Hickey, Chris S. Jones, Mohamed Z.Z. Jahufer and Cory Matthew
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Periodic drought is a severe constraint on the profitability
and sustainability of pastoral production. As a result of
climate change, drought events are anticipated to
increase in frequency and intensity even in regions where
annual precipitation is unchanged, as well as where it is
reduced.
Many studies have been carried out on drought
resistance of forage species (Holloway-Phillips and
Brodribb 2011). However, for most experiments, it is
unclear which mechanism(s) are responsible for variation
in plant performance under moisture stress, whether
drought response mechanisms were triggered, or whether
differences in performance were simply the result of
intrinsic plant vigour. The objective of the reported
research was to understand the underlying physiological
and genetic mechanisms responsible for production of
perennial ryegrass under summer drought and recovery
and regrowth after drought.
Drivers of pasture growth in perennial ryegrass pastures in northern New
Zealand dairy pastures.
Natalie R Mapp, Grant M Rennie and Warren McG King
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The critical importance of pasture production to New Zealand’s
economic performance has been widely recognised.
However, a number of critical issues have been identified
that limit dairy industry growth, including sub-optimal pasture
condition and poor pasture persistence. Dairy farm
systems in the Waikato and Bay of Plenty provinces in the
upper North Island of New Zealand are predominantly pasture-
based, with a temperate climate and they represent
around 30% of New Zealand’s total number of dairy farms
(LIC and DairyNZ, 2012). This project was established to
quantify pasture performance and identify factors that drive
that performance. We established a network of on-farm
trials where case studies of pasture renewal practices and
outcomes were developed. Ten farms in each province
were monitored for three consecutive years – four paddocks
from each province are considered here.
Economic values for perennial ryegrass traits in New Zealand dairy farm
systems
David F Chapman, Jeremy R Bryant, Graham A Kerr, Glenn Judson, Tim Cookson, Grant
R Edwards and William H McMillan
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Perennial ryegrass (Lolium perenne L.) is the main species
used in dairy pastures throughout New Zealand. There are
approximately 30 perennial ryegrass cultivars sold
commercially in New Zealand, but currently there is no
evaluation system which allows farmers to compare the
potential impact of different cultivars on the profitability of
their farm business. Such an economic evaluation system
requires information on performance values (PV) for
cultivars which quantifies their performance with respect to
the major productivity traits (herbage accumulation (HA,
kg DM/ha), nutritive value and persistence) relative to a
genetic base, and economic values (EV, Doyle and Elliott
1983) which estimate the additional profit resulting from
each unit change in the trait of interest (Equation 1).
Econom (1)
This paper describes a system modelling approach
developed to estimate EV for seasonal HA of pasture in the
major dairying regions of New Zealand. This information
is used in the DairyNZ Forage Value Index system
(www.dairynzfvi.co.nz) which is being developed to
include information on all three productivity traits for
commercially available ryegrass cultivars.
Effects of storage conditions on endophyte and seed viability in
pasture grasses
David E Hume, Stuart D Card and M Philip Rolston
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Several important temperate pasture grasses have co-evolved with mutualistic Epichloë fungal
endophytes. These endophytes impart beneficial attributes to their host as they enhance the fitness of the grass
when under biotic and abiotic stresses. The asexual species of these fungi (formerly classed as Neotyphodium)
are obligate symbionts, and efficiently colonise newly formed tillers and infect seed by direct colonisation of
the embryo. These endophytes are strictly seed transmitted. Survival of the fungus in this seed is therefore
critical for the dissemination of endophyte-infected seed to grassland farmers. Longevity of endophyte in
stored seed is primarily determined by the length of storage, temperature, and relative humidity as this is in
equilibrium with seed moisture. Elevated temperature and relative humidity both reduce endophyte viability.
The relative importance of each of these environmental parameters is unclear. Longevity may be further
modified by grass species, cultivar, seed lot, and endophyte strain. Valuable seed requiring long term storage
can utilise controlled storage facilities where temperature is preferably less than 5oC and relative humidity less than 30% (seed moisture less than 8%.
Keywords: Festuca arundinacea, Lolium perenne, Lolium hybridum, Lolium multiflorum, Epichloë,
Neotyphodium.
Efficient use of phosphorus in temperate grassland systems
Richard J Simpson, Alan E Richardson, Shirley N Nichols and James R Crush
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Phosphorus (P) fertilisers are important for high production in many grassland systems. However,
there are increasing environmental, economic and strategic issues associated with using P, which is a nonrenewable
and “effectively finite” global resource. We review the P balance of temperate pastures to identify
the factors that contribute to inefficient P use and discuss ways to improve P use efficiency. The most
immediate gains can be made by ensuring that pastures are not over-fertilised. Plants with low critical P
requirements, particularly as a result of better root foraging, will be important. Root traits such as fine roots
(root diameter), branching, length and root hairs, and mycorrhizal associations all contribute to improved root
foraging; some are amenable to plant breeding. Plants that can “mine” sparingly-available P in soils by
producing organic anions and phosphatases are also needed; as are innovations in fertiliser technology. Soil
microorganisms play a crucial role in P acquisition by pastures but are not particularly amenable to management.
Selection of pasture species for root characteristics offers a more realistic approach to improving P
efficiency but progress, to date, has been minimal. Traditional plant breeding, augmented by marker assisted
selection and interspecific hybridisation, are likely to be necessary for progress. Inevitably, P efficient
pastures will be achieved most effectively by a combination of plant genetic, fertiliser innovation and
management responses. Success will bring economic and environmental benefits from reduced P fertiliser
use, with consequent benefits for global resource and food security.
Keywords: Phosphorus use efficiency, phosphorus balance/surplus, root foraging, phosphorus mining,
fertilisers
Elevated CO2 impacts on grazed pasture: long-term lessons from
the New Zealand FACE
Michael B Dodd
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Abstract. A grazed pasture Free Air CO2 Enrichment (FACE) experiment has been operating for almost
15 years in the Rangitikei Region of New Zealand, following earlier work studying CO2, temperature and
moisture effects on pasture in growth chambers. The longer-term results are reviewed with a focus on
primary productivity, pasture compositional dynamics, nutrient cycling feedbacks and soil carbon supply.
In terms of the direct effects of CO2 elevated to 475 ppm, increases in primary production were reflected
in belowground allocation and legume stimulation, with the latter diminishing in the longer term and
annual aboveground net herbage accumulation showing a low and variable response over time. The
grazing animal has strongly influenced nitrogen (N) transformations, in terms of carbon (C) and N
decoupling and return to soil, a feedback that appears to mitigate the recognized effects of increased C
inputs on nitrogen limitation. Nevertheless, soil mineral N has decreased and labile fractions of soil
carbon have increased – effects only detectable over a decade. Key lessons unique to this study include
the animal and soil feedbacks that have driven longer-term effects differing from earlier growth chamber
and the results of FACE in the first few years. Remaining questions for further investigation include
mechanisms influencing legume responses and the effects of elevated CO2 on N processes (biological
fixation, microbial processing, mineral N losses). The facility is currently undergoing major
refurbishment in order
Endophytes for improving ryegrass performance: Current status and future
possibilities
Alison J Popay and David E Hume
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The endophyte N. lolii was introduced naturally into New
Zealand and Australia when perennial ryegrass seed was
brought into these countries. Although the presence of the
endophyte was recognised early in the 19th Century, its effects
were only discovered in the early 1980s when it was
found that these Wild-type strains of endophyte caused
ryegrass staggers, a neuromuscular condition of grazing
animals (Fletcher and Harvey 1981), and that they also protected
their hosts from the effects of Argentine stem weevil
(Listronotus bonariensis) a serious pest of ryegrass in New
Zealand (Prestidge et al. 1982). These endophytes form
systemic infections in the above-ground parts of their host
plants, have no external stage and are maternally transmitted
in seed. They produce alkaloids which have effects on
herbivores, including sheep, cattle and invertebrates. Although
all the alkaloids known to be produced by the
endophytes have bioactivity against insects, not all are toxic
to livestock. Research in New Zealand has focused on
exploiting these endophytes for their natural biological control
properties while minimising any effects on livestock.
Establishment and growth of legumes on uncultivatable hill country in
East coast New Zealand
Trevor L Knight,Tom J Fraser, Paul D Muir and Chikako van Koten
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Steep, non-arable hill country is a significant feature of
New Zealand farming (Sheath 2011) and large tracts of it
have been improved by over-sowing grass and assorted
clover species, particularly white clover (Trifolium repens
L.). Numerous other legume species are available in New
Zealand from similar environments overseas that may be
more productive on some steep hill country. Plant breeders
in New Zealand have also produced inter-specific hybrids
(Williams et al. 2010) with potentially useful attributes. As
part of a large project to increase pasture production on
non-arable hills, a range of legume species were established
at 2 sites in New Zealand in 2012. This paper reports
results from the first spring and early summer following
establishment.
Evaluating the benefits of restricted grazing to protect wet pasture
soils in two dairy regions of New Zealand
Pierre C Beukes, Alvaro J Romera, Dave A Clark, Dawn E Dalley, Mike J Hedley, David J Horne, Ross M Monaghan and Seth Laurenson
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Abstract. Many dairy farms in the Manawatu and Southland regions of New Zealand have poorly drained
soils that are prone to treading damage, an undesirable outcome on grazed pastures during the wetter months
of the year. Removing cows to a stand-off pad during wet conditions can reduce damage, but incurs costs.
The objective of this study was to evaluate the impact of different levels of restricted grazing (from 0 to 10
hours grazing time/day for lactating cows) on pasture yield, damage and wastage, feed and stand-off expenses,
and farm operating profit. A simulated farm from each region was used in a farm systems model. This
model simulated pasture-cow-management interactions, using site-specific climate data as inputs for the soilpasture
sub-models. Days to recover previous yield potential for damaged paddocks can vary widely. A sensitivity
analysis (40 to 200 days to recover) was conducted to evaluate the effect of this parameter on results.
Full protection when there is risk of damage (0 grazing hours/day) appeared to be less profitable compared
with some level of grazing, because the advantages of reduced damage were outweighed by the disadvantages
of managing infrequently grazed pastures. The differences in operating profit between full protection and
some level of grazing became less as the recovery time increased, but for both regions grazing durations of 6-
8 hours/day when a risk of damage is present appeared to be a sensible strategy irrespective of recovery time.
Keywords: Treading damage, pasture utilization, profitability, simulation modelling, stand-off area
Ewe body condition: Does farmer practice meet research guidelines?
Marie J Casey, John S Scandrett and David R Stevens
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A group of sheep farmers in the Southland region of New
Zealand were surveyed in the winter of 2011 to determine
their current winter management practices and ewe
performance. This followed a 3 year Sustainable Farming
Fund project to investigate if there was a relationship
between maintaining an even ewe body condition score
(BCS) during pregnancy and the incidence of vaginal
prolapse (bearings). The program included a series of
workshops to help farmers improve their ewe winter
management and it became apparent that the actual winter
feeding practice and ewe performance was relatively
unknown.
The research was done to document current farmer
winter feeding and management practices and subsequent
whole flock reproductive performance.
GrassView - the form and function of grass: a multimedia program
E.P. ASHLEY, C. MATTHEW and J. HODGSON
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GrassView – the form and function of grass is an
interactive computer programme which uses video
footage, narration, sound, computer based 3D
animation, graphical displays of information, charts
and quizzes to present a description of the
morphology of a grass tiller and the implications
for sward behaviour. The programme is designed
for flexibility of use. In interactive mode it could
be used for self-directive study, whereas in linear
mode it could be video-projected as a presentation
to a class of students or to an assembled group. It
has been optimised to run under Windows 95 or
NT 4.0 and is distributed as a CD.
Keywords: computer program, grass form and
function, grass morphology, interactive program,
leaf extension,
Growth of the grass plant in relation to seed production
R.H.M. Langer
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The specialized management techniques
required for successful seed production in
grasses must be based on a sound understanding of
the physiology of the plant.
Seed yields depend strongly on the number of ears
per unit area, and early-formed tillers are largely responsible
for producing these ears. Numbers of fertile
tillers are generally increased by early spring
applications of nitrogen fcrtilizer and autumn grazings,
but can be seriously reduced by defoliation after
floral initiation and ear development have started.
Seed yields from later formed tillers can be improved
by using nitrogen fertilizer to increase the
numbers of seeds per ear and the mean seed weight.
Key ,clords: Seed production, grasses, fertile tillers,
nitrogen, grazing.
Herb and clover mixes increase average daily gain (ADG) of finishing
lambs in different seasons
Sharini C Somasiri, Paul R Kenyon, Peter D Kemp, Patrick CH Morel and Stephen T Morris
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Approximately half of the usable land area in New Zealand
is under grasslands (Saggar 2001). Production of lamb meat
is seasonal in New Zealand (Fisher 2004) with the majority
of lambs born in the spring and slaughtered in late summer
and autumn depending on the international demand (Clemens
and Babcock 2004) and pasture growth pattern.
Finishing lambs outside this window using high quality
pastures would help to facilitate a continuous supply of
meat to the domestic and international markets. Charlton
and Belgrave (1992) and Kemp et al. (2010) reported that
the use of herb-clover mixes instead of perennial ryegrass/
white clover swards would facilitate finishing lambs
to a high carcass weight or in a shorter time period. Therefore,
a research was undertaken in four different seasons:
early spring, late spring, summer and autumn during
2011/2012 with the hypothesis that the average daily gain
(ADG) and average live weight per ha per day of finishing
lambs would be greater in herb-clover mixes than on a perennial
ryegrass/white clover sward.
Improved drought stress tolerance of white clover through
hybridisation with Trifolium uniflorum L.
Shirley N Nichols, Rainer W Hofmann, Isabelle M Verry and Warren M Williams
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The objective of this study was to determine the effect of hybridisation with Trifolium uniflorum L.
on drought resistance of Trifolium repens L. (white clover). Shoot dry weight of backcross 1 (BC1) hybrids
was reduced less by water stress than for backcross 2 (BC2) hybrids and white clover, as were key
morphological traits such as leaf area. Under water stress, important differences for the BC1 generation
compared to white clover also included lower senescence, higher stolon density, increased root dry weight,
and a higher maximum nodal root diameter. Drought decreased the net photosynthetic rate by up to 48% in
BC2 and white clover, but there was no significant effect on the BC1 generation. BC1 hybrids were therefore
more resistant to water stress than white clover. Smaller effects on stolon morphology suggest BC1 hybrids
were better able to maintain cell turgor and growth, and maintenance of photosynthesis under drought may
have contributed to smaller reductions in productivity. The findings suggest that BC1 hybrids may be able to
maintain higher water uptake during drought than white clover by increased allocation to root biomass.
Keywords: Trifolium repens, water stress, dry matter production, senescence, morphology, photosynthesis.
Improving summer/autumn feed quality in New Zealand hill country
Grant M Rennie, Warren McG King, Coby J Hoogendoorn, Brian Devantier, Trevor L Knight
and Catherine Cameron
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Pasture management in spring has a strong influence on
pasture quality in summer and autumn in New Zealand hill
country pastures. Manipulation of defoliation frequency
and intensity during mid-late spring can impact summer
and autumn pasture quality and quantity (Orr et al. 1988).
Summer/autumn management is mainly concerned with
maintaining herbage quality in summer wet areas and
controlling animal pressure in summer dry areas for
drought management and winter feed stocks (Clark 1994).
Deferred grazing to transfer pasture growth from late spring
into summer and autumn deficits is difficult due to
detrimental effects on pasture quality, plant density and
species composition (Sheath et al. 1987). Various grazing
management models have been published to inform hill
farmers of pasture management considerations during this
period (Smith and Dawson 1977; Sheath and Bircham
1983; Sheath et al. 1987).
It has previously been shown that management of late
spring surpluses to restrict reproductive growth will
increase summer pasture quality through a reduction in
accumulated stem and dead material and an increase in
clover content (Sheath et al. 1987). However, there is no
information on the longevity of these effects. This trial
aimed to determine the effect of different defoliation
intensities during spring on herbage quality and
composition throughout the subsequent summer-autumn
period.
Inter-annual variability in pasture herbage accumulation in
temperate dairy regions: causes, consequences, and management
tools
David F Chapman, Richard P Rawnsley, Brendan R Cullen and David A Clark
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Abstract. Inter-annual variation in pasture herbage accumulation rate (HAR) is common in temperate dairy
regions, posing challenges for farmers in the management of dairy cow feeding and of pasture state. This
paper reviews the biophysical factors that cause inter-annual variation, considers some of its consequences for
the efficient harvest of pasture, and discusses the basis for decision rules and support tools that are available
to assist New Zealand and Australian farmers to help manage the consequences of an imbalance between feed
supply and demand. These tools are well-grounded in scientific research and farmer experience, but are not
widely used in the Australasian dairy industries. Some of the reasons for this are discussed. Inter-annual
variability in HAR cannot be removed, even with inputs such as irrigation, but reliable forecasts of pasture
HAR for a month or more could greatly improve the effectiveness of operational and tactical decisionmaking.
Various approaches to pasture forecasting, based on pasture growth simulation models, are
presented and discussed. Some of these appear to have reasonable predictive ability. However, considerably
more development work is needed to: (1) prove their effectiveness; and (2) build the systems required to
capture real-time, on farm data for critical systems variables such as pasture herbage mass and soil water
content to combine with daily weather data. This technology presents an opportunity for farmers to gain
greater control over variability in pasture-based dairy systems and improve the efficiency of resource use for
profit and environmental outcomes.
Keywords: Climate variability, decision rules, forecasting.
Inter-annual variability in pasture herbage accumulation in
temperate dairy regions: causes, consequences, and management
tools
David F Chapman, Richard P Rawnsley, Brendan R Cullen and David A Clark
view more
Abstract. Inter-annual variation in pasture herbage accumulation rate (HAR) is common in temperate dairy
regions, posing challenges for farmers in the management of dairy cow feeding and of pasture state. This
paper reviews the biophysical factors that cause inter-annual variation, considers some of its consequences for
the efficient harvest of pasture, and discusses the basis for decision rules and support tools that are available
to assist New Zealand and Australian farmers to help manage the consequences of an imbalance between feed
supply and demand. These tools are well-grounded in scientific research and farmer experience, but are not
widely used in the Australasian dairy industries. Some of the reasons for this are discussed. Inter-annual
variability in HAR cannot be removed, even with inputs such as irrigation, but reliable forecasts of pasture
HAR for a month or more could greatly improve the effectiveness of operational and tactical decisionmaking.
Various approaches to pasture forecasting, based on pasture growth simulation models, are
presented and discussed. Some of these appear to have reasonable predictive ability. However, considerably
more development work is needed to: (1) prove their effectiveness; and (2) build the systems required to
capture real-time, on farm data for critical systems variables such as pasture herbage mass and soil water
content to combine with daily weather data. This technology presents an opportunity for farmers to gain
greater control over variability in pasture-based dairy systems and improve the efficiency of resource use for
profit and environmental outcomes.
Keywords: Climate variability, decision rules, forecasting.
Levy oration – 2014: Agricultural science and extension
J. D. MORTON
view more
Since this oration is in the name of Sir Bruce Levy,
I took the time to Google his biography and found it
in the Te Ara Encyclopedia of New Zealand. Many of
us are aware of his role as the Father of New Zealand
Grasslands with his message of fertiliser, improved
pasture cultivars and the efficient cycling of nutrients
through grazing. But what interested me was his
extension technique with farmers. This was described
as akin to a sergeant major (Sir Bruce) dressing down
the latest group of raw recruits (the farmers). It was
clearly suitable for those times. Interestingly, Sir Bruce
Levy, in taking his research findings out directly to
farmers, was emulated by other notable scientists such
as McMeekan and Brougham.
Levy oration – 2014: Agricultural science and extension
J. D. MORTON
view more
Since this oration is in the name of Sir Bruce Levy,
I took the time to Google his biography and found it
in the Te Ara Encyclopedia of New Zealand. Many of
us are aware of his role as the Father of New Zealand
Grasslands with his message of fertiliser, improved
pasture cultivars and the efficient cycling of nutrients
through grazing. But what interested me was his
extension technique with farmers. This was described
as akin to a sergeant major (Sir Bruce) dressing down
the latest group of raw recruits (the farmers). It was
clearly suitable for those times. Interestingly, Sir Bruce
Levy, in taking his research findings out directly to
farmers, was emulated by other notable scientists such
as McMeekan and Brougham.
Methods for estimating seed production of two summer-active grass
weeds, Setaria pumila and Digitaria sanguinalis, in New Zealand dairy
pastures
Katherine N Tozer and Catherine A Cameron
view more
Undesirable C4 annual grasses such as summer grass
(Digitaria sanguinalis, (L.) Scop., SG) and yellow bristle
grass (Setaria pumila (Poir.) Roem. et Schult., YBG) are
prevalent in dairying regions in the North Island of New
Zealand. Field surveys of 39 dairy pastures in the central
North Island demonstrated that their percentage ground
cover has tripled over the last four years (Tozer et al.
2012). The prolific seed production of these species is
thought be facilitating this increase in ground cover.
However, little information is available on their fecundity
in dairy pastures. Counting the number of seeds in a panicle
is slow and laborious, therefore a rapid and robust method
to assess fecundity is required. In USA crops, Forcella et
al. (2000) found a significant curvilinear relationship
between YBG seeds per panicle and panicle length,
regardless of crop identity, year and weed density. A study
was therefore established to determine if panicle length or
weight could be used to estimate YBG and SG fecundity in
intensively managed dairy pastures in New Zealand.
More summer milk - an on-farm demonstration of research principles
R.J. SHAW, N.A. THOMSON, D.F. McGRATH and J.E. DAWSON
view more
An on-farm demonstration over the 1996/97
dairying season of management systems designed
to increase summer milksolids production is
presented. The extra summer feed was obtained
by: (1) (3 farms), the application of 70 kg N
fertiliser/ha over the late spring early summer
(applied as a split-dressing of 30 and 40 kg N/ha);
(2) (2 farms), the incorporation of 5–10% of the
farm in turnips in conjunction with the application
of 60 kg N/ha applied over the crop establishment
period (30 kg N/ha applied in October at
cultivation and 30 kg N/ha applied in December);
and (3) (2 farms), maize silage fed out in early
summer at 4 kg DM/cow/day for 60 days. Before
applying the treatments the farm and herds were
split into two equal units and the comparisons
made between the control and treatment splits
within farms. Summer pasture production was high
owing to above-average rainfall. This resulted in
only a 10.2% decline in production from peak to
end of lactation over the seven demonstration
farms. However, despite the more favourable
season the additional feed inputs on all farms
increased milksolids production. The treatment’s
milksolids responses were: N fertiliser 36 kg MS/
ha, turnips and N fertiliser 34 kg MS/ha, maize
silage 22.5 kg MS/ha. The average profits to the
treatments were: N fertiliser $54/ha, turnips and N
fertiliser $27/ha, and maize silage $123/ha. The
returns were reduced by the favourable summer
for pasture production but they demonstrated the
type of on-farm responses that can be achieved.
The results highlight that profits to additional feed
inputs are primarily determined by the level of
pasture shortage and the cost of feed inputs. The
concept of split-herd comparisons between a
control situation and a management input on
commercial dairy farms proved an excellent
extension method.
Keywords: farm profit, maize silage, nitrogen
fertiliser, turnips, on-farm demonstration, summer
milksolids production
Nitrate leaching is similar in N2 fixing grass-clover pasture and N-fertilised grass-only pasture at similar N inputs
M.S. SPROSEN, S.F. LEDGARD and E.R. THOM
view more
Nitrate leaching losses were measured in farmlets
containing ryegrass–clover pasture which received
most of its nitrogen (N) input in the form of N2
fixation by white clover, or a ryegrass-only pasture
which received a similar amount of N in the form
of urea fertiliser. The farmlets were rotationally
grazed by dairy cows between 1993 and 1996 at
the Dairying Research Corporation’s No. 5 dairy,
Hamilton. Total N inputs ranged from 146 to 200
kg/ha/year. Total pasture production was similar
in both treatments in year 2, but was 22% lower in
the grass–clover pasture in year 3. Milk production
was similar for both farmlets in years 1 and 2, but
was not measured in year 3. Nitrate concentrations
in the leachate were measured using ceramic cup
collectors at 1 m depth. The average nitrate-N
concentration in leachate over the 3 years was 3.9
and 3.7 mg/litre for the fertiliser and clover
treatments, respectively. This is well below the 11
mg nitrate-N/litre limit set for drinking water. Over
the 3 years of the trial, 76 and 71 kg N/ha were
leached from the fertiliser and clover treatments,
respectively. Thus there was no significant
difference between N sources in the amount of
nitrate-N leached.
Keywords: dairying, nitrate leaching, nitrogen
fertiliser, N2 fixation
Nitrate leaching is similar in N2 fixing grass-clover pasture and N-fertilised grass-only pasture at similar N inputs
M.S. SPROSEN, S.F. LEDGARD and E.R. THOM
view more
Nitrate leaching losses were measured in farmlets
containing ryegrass–clover pasture which received
most of its nitrogen (N) input in the form of N2
fixation by white clover, or a ryegrass-only pasture
which received a similar amount of N in the form
of urea fertiliser. The farmlets were rotationally
grazed by dairy cows between 1993 and 1996 at
the Dairying Research Corporation’s No. 5 dairy,
Hamilton. Total N inputs ranged from 146 to 200
kg/ha/year. Total pasture production was similar
in both treatments in year 2, but was 22% lower in
the grass–clover pasture in year 3. Milk production
was similar for both farmlets in years 1 and 2, but
was not measured in year 3. Nitrate concentrations
in the leachate were measured using ceramic cup
collectors at 1 m depth. The average nitrate-N
concentration in leachate over the 3 years was 3.9
and 3.7 mg/litre for the fertiliser and clover
treatments, respectively. This is well below the 11
mg nitrate-N/litre limit set for drinking water. Over
the 3 years of the trial, 76 and 71 kg N/ha were
leached from the fertiliser and clover treatments,
respectively. Thus there was no significant
difference between N sources in the amount of
nitrate-N leached.
Keywords: dairying, nitrate leaching, nitrogen
fertiliser, N2 fixation
Pasture improvement needs and options for New Zealand sheep and beef
farms
Andy R Bray, Tom J Fraser, Warren McG King, Alec D Mackay, Derrick Moot, David R Stevens
view more
In recent years in New Zealand, sheep and beef farming
has been outcompeted for prime land. This means that
the government and industry targets to increase sheep
and beef production have to be achieved on farms with
significant constraints on pasture production. They are
increasingly restricted to hilly and other locations with
variable climates and soils, and landscape constraints on
farming practices. Thus there are limits on the ability to
improve pasture production – whether by pasture renewal
or through means like grazing management, fertiliser use,
or weed and pest control.
Sheep and beef farmers want to improve the growth
of young animals under these conditions and the New
Zealand Government has set a target to double exports of
primary products by 2025. The challenges lead to the
formation of a research programme to improve
production from permanent pastures on sheep and beef
farms. Through Beef + Lamb New Zealand they have
identified the following aspects as priorities for
improvement - early spring feed supply, summer-autumn
feed quality and integrated management of land units that
differ in the amount and seasonal pattern of forage
production.
Pasture pests - are they the real problem?
Colin M Ferguson and Sue Peoples
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The New Zealand grass grub, Costelytra zealandica
(White)(Coleoptera: Scarabaeidae) and species of the porina
complex, Wiseana spp. (Lepidoptera: Hepialidae),
(hereafter referred to as ‘porina’) are endemic New Zealand
insects whose larvae have a long history as significant, intransigent,
agricultural pests. Both affect pasture production
and plant composition in most regions of the country. Grass
grubs are root feeders while porina caterpillars, although
dwelling in permanent subterranean burrows, emerge at
night to feed on above ground plant foliage. Both find ryegrass
and white clover, the basis of most New Zealand
pastures, very favourable food plants. The life histories and
larval development of both are well understood and the
onset of damage caused by both insects is related to development.
Pasture damage as a result of their feeding is
generally first noticed by farmers in late autumn and becomes
more severe through winter as their body sizes
increase and plant growth slows.
Pasture production of Northern dairy farms
G.J. PIGGOT
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Pasture production and pasture and farm
management parameters were measured on 53 farms
between 1989 and 1996 in Northland, Waikato
and Bay of Plenty. The annual data sets are from
135 seasons each beginning before calving – 90
from Northland, 34 from the Bay of Plenty, and 11
from the Waikato, including a farmlet on No. 2
Dairy at Ruakura. Most farms were of the
conventional spring-calving system, but autumn
calving farms and irrigated systems were also
visited. Visits were monthly except for 12 farms
with 10 visits a year. Pasture growth was assessed
from a trimmed “cage” technique, and from a
“whole-farm” technique which involved calculating
the growth required to maintain the livestock
feeding regime plus any change in farm cover.
Annual yield from the cage technique averaged
14.8 (± SE 0.2) t DM/ha while the whole-farm
yield was 11.4 ± 0.1 t DM/ha or 77% of cageassessed
yield. The difference between cage and
whole-farm growth occurred in all months but was
greatest in September and from January to May.
The range in whole-farm annual yield was large
(8.5 to 15.6 t DM/ha), the lowest and highest yields
occurring on irrigated farms. Low yields, however,
tended to be associated with farms on clay hill
country in Northland. Examples are provided for
using these data for calculating the farm stocking
rate and calving date, and also for comparing the
effect of management factors on pasture growth.
Keywords: cage technique, pasture assessment,
pasture production, whole-farm technique
PLANT RESISTANCE TO INSECT PESTS
R. P. POTTINGER
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THE UTILIZATION of plant resistance against insect pests is not a
new phenomenon in New Zealand, but until the present decade
it has been largely concerned with resistance in horticultural
(Lamb, 1953a; Smith et al., 1960; Colttier, 1948), cereal (Marrisen,
1938) and fodder crops(Lamb, 1953b; Palmer, 1956,
1965; Palmer and Smith, 1967).
Plantain (Plantago lanceolata) in herb and legume pastures increases lamb
growth relative to perennial ryegrass and white clover pasture
Peter Kemp, Paul R Kenyon, Stephen T Morris and Sharini C Somasiri
view more
Increased use of plantain (Plantago lanceolata) by New
Zealand farmers has created a demand for a more
complete understanding of the performance and management
of plantain by itself and in various combinations
with chicory (Cichorium intybus) and legumes such as
white clover (Trifolium repens) and red clover (T.
pratense). The objective of this study was to evaluate
lamb finishing on plantain by itself and combined with
chicory, white and red clover as part of a research
programme to develop a temperate perennial pasture
superior in animal performance to perennial ryegrass and
white clover pasture for sheep production systems (Kemp
et al. 2010).
Plantain (Plantago lanceolata) outperforms chicory (Cichorium intybus)
under moisture stress in glasshouse
Lydia M Cave, Peter D Kemp, Paul R Kenyon and Stephen T Morris
view more
Forage chicory (Cichorium intybus) and plantain (Plantago
lanceolata) are now widely used throughout the world as
high feed quality perennial herbage (Sanderson et al. 2003;
Labreveux et al. 2006; Li et al. 2010; Golding et al. 2011;
Hutton et al. 2011). Both are taprooted plants and are thus
likely to confer a degree of drought tolerance through accessing
water deeper in the soil profile (Kemp et al. 2010).
Nie et al. (2008) reported chicory can tolerate moisture
stress to a greater degree than plantain. However, overall
little is known about the effect of moisture stress on plantain
and chicory persistence under defoliated conditions.
The objective was to compare plantain and chicory under
moisture stress and defoliation under glasshouse
conditions.
Revitalising communities to sustain grassland research
Jacqueline Rowarth
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Participation in science subjects at school and University has decreased in developed countries as
the curriculum has broadened and the proportion of students staying on at school and entering university has
increased. Global shortfalls in STEM graduates (Science, Technology, Engineering and Mathematics) mean
an increase in salaries, which in turn are decreasing the likelihood of students staying on at University for
postgraduate study. This is unfortunate given the increasing challenges in sustainable food production –
grassland research needs great people enjoying great careers in order to contribute to global sustainability.
This paper addresses the complex issues which have been the foundation for current generations, and
considers what can be done to ensure that communities are revitalised to sustain grassland research.
Keywords: Schools, career opportunities, research.
Ryegrass seeding rate alters plant morphology and size – possible
implications for pasture persistence?
Julia M Lee, Errol R Thom, David F Chapman, Kate T Wynn, Deanne Waugh
and Laura Rossi
view more
Poor persistence of perennial ryegrass (Lolium perenne L.)
is a major dairy industry issue in New Zealand and
Australia. New ryegrass seed is often drilled at 18-30
kg/ha, although previous research indicated that pastures
drilled at 10-12 kg/ha can be just as productive (Frame and
Boyd 1986; Praat et al. 1996). High seeding rates increase
competition between developing seedlings for light, water
and nutrients, reduce plant size (Harris 1990) and
potentially survival.
The experiment reported here investigated the effect of
plant density (created by differences in seeding rate) on
plant morphology and survival. The hypothesis was that
plants established from high seeding rates will be smaller
and, therefore, less likely to survive the first summer; a
period of substantial environmental stress (e.g., high
temperatures, low soil moisture, insect attack).
Selected endophyte: seed industry intentions
WARWICK GREEN and JOHN MCKENZIE
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Perennial ryegrass (Lolium perenne L.) forms the
basis of New Zealand’s high fertility pasture. High
levels of endophyte (Neotyphodium lolii) are
commonly used to ensure persistence. The New
Zealand Plant Breeding and Research Association
and AgResearch have entered into an agreement to
commercialise AR1, a new selected endophyte with
high peramine, low lolitrem and low ergovaline
levels. A number of commercial cultivars have
been inoculated and these are now going through
an agreed validation process with animal performance
and agronomic trials being conducted
throughout New Zealand. The seed industry is not
currently in a position to confirm a commercialisation
date, but it will not be before 1 January 2001.
The parties, though confident that this initiative
will be successful, remain committed to having as
many questions answered, before the release date,
as possible.
Keywords: AR1, commercialisation, endophyte,
ergovaline, lolitrem, Neotyphodium lolii, peramine,
perennial ryegrass, seed
State of knowledge in tiller dynamics
Cory Matthew, Mónica G Agnusdei, Silvia G Assuero, André F Sbrissia, Omar
Scheneiter and Sila C Da Silva
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Abstract. Persistence of sown pastures is a concern for pastoral production worldwide. Fundamentally, when
a pasture does not persist the problem can be expressed in terms of inadequate new tiller production or
excessive tiller death. However, the collection of data to build an understanding of sward dynamics at this
level is time consuming. Tiller survival diagrams are presented for a range of temperate and tropical grass
species including Lolium perenne, Lolium multiflorum, Festuca arundinacea, Festuca pratensis, Phleum
pratense, Bromus willdenowii, Cynodon dactylon, Brachiaria brizantha, Panicum maximum, Chloris gayana
and Paspalum notatum. It is shown that each grass has a unique perennation strategy and accordingly unique
strengths and weaknesses that confer persistence or lack of persistence in different situations. There is also
confusion in extension circles about the trade-off between tiller size and tiller density and how to detect a
suboptimal tiller density. Grass swards respond to high herbage mass by increase of tiller size and reduction
in tiller density, but reduction in tiller density is often mistaken for sward decline. A distinction must be made
between size/density compensation and sward decline. Increased understanding of sward dynamics at this
level should help in the evolution of management practices that improve persistence on a range of grassland
types.
Keywords: Perennation strategy, flowering, biennialism.
Successful establishment of oversown chicory and plantain on
uncultivatable hill country
Grant B Douglas, Katherine N Tozer, Catherine Cameron, Tom J Fraser, Paul D Muir, Ray A Moss, Grant M Rennie and Trevor L Knight
view more
All-year grazing of livestock on steep, non-arable hill
country (>20o slope angle, <1,000 m elevation) is a
significant feature of New Zealand agriculture. Hill country
pastures are in various states of improvement depending on
factors such as extent of subdivision, fertiliser inputs, plant
species introduction, and grazing management. Numerous
introduced grass, legume and herb species are available to
match the many micro-sites in steep hill country (Kemp et
al. 1999).
There has been increasing use of the perennial herbs
chicory (Chicorium intybus L.) and plantain (Plantago
lanceolata L.) in seed mixtures used on a range of
topographies, mostly flat to undulating terrain. Advantages
of these species include tolerance of drought and high
summer temperatures, highly palatable foliage, enhanced
mineral content, and high animal growth rates (Stewart
1996; Li and Kemp 2005). Farmers have sown these
species on hill country but there is negligible information
on their establishment in such landscapes. As part of a
large, New Zealand-wide programme to increase pasture
productivity on non-arable hill country through new
germplasm introduction, chicory and plantain were
included in a seed mixture broadcast-sown at a range of
sites. This paper reports on the seedling establishment of
these two species.
The dilemma of using sward height as a management tool for intensively
grazed sheep pasture in spring
David R Stevens, Andrew J Wall, Bryan R Thompson, Karren T O’Neill and Ian C Scott
view more
Sward height is often used as a tool for both animal and
pasture management, especially when continuously grazing
pasture. For example, sward height has been used to define
the conditions for optimal feed intake of multiple-bearing
ewes, both before and after lambing (Everett-Hincks et
al.2005; Morris and Kenyon 2004). Sward height is easily
applied by the grazier and so becomes an effective tool.
However, changes in the leaf distribution and relative
species makeup of the sward both seasonally (Thomson et
al. 2001) and in response to grazing management (Webby
and Pengelly 1986) mean that the amount of pasture per
unit height will change. When these changes occur a
dilemma is presented to the grazier. How do they manage
the trade-off between a simple indicator for management
decisions and the lost opportunity of harvesting pasture
mass that may be accumulating below the assigned sward
height?
This paper presents data from an experiment that
investigated the impacts of defoliation strategies on sward
of differing starting masses, with defoliation management
based on height rather than mass. The paper quantifies the
accumulation of herbage below defoliation height and
highlights the dilemma of using sward height as a
management tool when aiming to maximise the utilisation
of our pasture resource.
The effect of novel endophyte and insecticide seed treatment on the
establishment of long rotation or perennial ryegrass plants in the presence
of adult Argentine stem weevil (Listronotus bonariensis)
Wayne W Nichol and Simon F Walker
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Argentine stem weevil (Listronotus bonariensis (Kuschel))
is a recognised pasture pest throughout most regions of
New Zealand including an increasing threat to the southern
half of the South Island (Popay et al. 2011). Mitigation options
for control of adult Argentine stem weevil (ASW)
during establishment of ryegrass are available. The following
study investigated the potential for seed infected with
novel endophytic fungi Neotyphodium sp.(Clavicipitaceae:
Hypocreales) and/or seed treated with systemic insecticide
to improve the survivability of ryegrass seedlings in the
presence of adult ASW in South Otago, New Zealand
Trifolium occidentale: a valuable genetic resource for white clover
improvement
Syed W Hussain and Warren M Williams
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Trifolium occidentale Coombe is a stoloniferous, diploid
(2n=2x=16) perennial clover indigenous to Portugal, Spain,
France, and the British Isles. It grows in relatively dry
coastal habitats, in sand dunes and on shallow pocket of
soil (Coombe 1961; Coombe and Morisset 1967). As the
species grows naturally in saline, dry habitats, it is potentially
a source of drought tolerance genes that could be used
for the improvement of white clover (Trifolium repens L.)
cultivars. Although T. occidentale is reported to be one of
the progenitors of white clover (Williams et al. 2012), the
2x forms of T. occidentale cross with difficulty with white
clover, resulting in near-sterile triploid hybrids. The two
species were first crossed by Chou and Gibson (1968) and
subsequently by Gibson and Beinhart (1969), and Chen and
Gibson (1974). The relative success of producing F1 hybrids
was increased by use of colchicine doubled (4x) T.
occidentale. Based on these reports, our objectives were:
(1) to artificially double the chromosomes of T. occidentale
using colchicine; (2) to use tetraploid (4x) T. occidentale as
the pollen parent in crosses with white clover to produce
large numbers of F1 hybrids; (3) to evaluate hybrids both
cytologically and morphologically; and (4) to develop advanced
backcross and intercross progeny for future
breeding and selection using white clover as the recurrent
parent.
Widening the adaptation of white clover by incorporation of
valuable new traits from wild clover species
W M Williams, I M Verry, S W Hussain, H A Ansari, K H Widdup, N W Ellison,
and SN Nichols
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Although white clover (Trifolium repens) is the most widely used legume in grazed pastures of
temperate and sub-tropical regions, it is severely restricted in genetic diversity for adaptive traits to low soil
fertility and other stress environments, including drought. The objective of this research was to transfer traits
for wider adaptation from other clover species by hybridisation. Eight Trifolium species with contrasting
adaptations were shown by DNA sequence phylogenetics to be closely related to white clover. Interspecific
hybridisation was undertaken among these species using embryo rescue, and an array of partially fertile F1
hybrids was obtained. Population development from these F1 hybrids showed that hybrids involving six taxa
could be selected for high sexual fertility. Most showed strong inter-species chromosome pairing and the
potential for introgression of exotic genomes into white clover. Several of the new genomic combinations,
which do not occur in nature, will improve prospects for extending the adaptive range of white clover.
Keywords: Trifolium repens, interspecific hybridisation, Trifolium ambiguum, Trifolium occidentale,
Trifolium nigrescens.
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