H. S. Easton

Tall fescue in Australia and New Zealand

Abstract Tall fescue is widely naturalised in Australia and New Zealand. Its use in pastoral agriculture has developed with the availability of suitable cultivars. Naturalised tall fescue is infected with Acremonium endophyte and is known to be toxic. The significance of endophyte is briefly discussed. Tall fescue can be slow to establish after sowing, and palatability is sometimes inadequate. Greatly enhanced winter growth, through the use of Mediterranean germplasm, would extend use of the species into more summer‐dry environments. Research supporting these and other objectives is reviewed. Current breeding programmes in Australia and New Zealand are described.

Some effects of diet on beef meat and fat attributes

Abstract Steers were fed for nine weeks on either ryegrass/clover pasture or maize (six animals per group), to evaluate the effects of diet on attributes of meat and fat. Feed intake was restricted in the grain‐fed group with the intention of producing equivalent growth rates in the two treatment groups, but this resulted in significantly slower weight gain, reduced carcass weight, and reduced subcutaneous and intramuscular fat. Nevertheless, the glycolytic potential (an estimate of pre‐slaughter glycogen) in the M. longissimus dorsi lumborum was approximately 20% higher (P < 0.05) in the grain‐fed cattle, while the ultimate pH of the meat was equivalent for both groups. The results suggest that grain‐based diets can increase muscle glycogen concentrations independent of the higher calorific intake normally associated with grain diets, probably in response to changes in rumen fatty acid production. Compared with grain diet, pasture diet resulted in significantly higher (P < 0.01) muscle tocopherol content...

Future options and targets for pasture plant breeding in New Zealand

Abstract Industries based on pastoral farming have increased their contribution to GDP from 13.5 to 17% since 1990 as the result of markedly intensified farming practices. In the future, we predict that this intensification will continue but, at the same time, there will be an emergence of an efficient, lower‐input farming sector with almost no environmental footprint. Both sectors will require continuing input by pasture plant breeders. Over the past 20 years, development of pasture cultivars has become totally industry funded, with support from Crown funding for basic research. There have been several key advances in pasture plant breeding including new methods for using exotic germplasm and secondary gene‐pools, modification of grass‐en‐dophyte associations, breeding for specific environments and the successful adoption of international breeding programmes. The emergence of genom‐ics, marker‐assisted selection (MAS) and genetic modification (GM) offer considerable promise for future development of pasture cultivars. Future grass breeding, aided by MAS and GM of both plants and endophytes, will place strong emphasis on feeding value for optimal animal performances, especially in intensive systems. There will also be development of grass types adapted to efficient, lower‐input farming systems that will have minimal environmental impacts. White clover breeding has had a period of unprecedented input built on a strong foundation of knowledge and germplasm. For intensive agriculture, future breeding will emphasise disease and pest resistance, improved feed quality, seed production and the development of hybrid cultivars. For lower‐input sustainable systems, breeding will aim to broaden the adaptation of clover to semi‐arid and other marginal environments. This will involve increasing use of related clover species in interspecific hybrids, and selection for improved phosphate efficiency, N‐fixation and drought tolerance. DNA technologies will provide an increasingly valuable contribution to these products but the predominant effort will involve plant breeding methods that re‐combine and select whole genomes. New Zealand farming is based on a small number of pasture plant species and, despite the expanded use of the herbs chicory and plantain, this number has reduced with intensification. It is predicted that some expansion of the species base will be needed in future to cope with climate warming and the development of a sustainable low‐input farming sector. In particular, subtropical grasses should be investigated more thoroughly along with ways of enabling (perhaps new) legumes to be used with them. Despite a relatively enlightened germplasm introduction programme, the germplasm base of most pasture species is inadequate and requires continued effort to locate and import new materials from diverse international sources. International research networks have been developed in recent years and these will increasingly contribute to future pasture plant breeding progress. The current biosecurity and Hazardous Substances and New Organisms regulatory environment is not conducive to timely research and innovation on new species for agriculture and needs reconsideration by law makers.

Influence of the ryegrass endophyte (Neotyphodium lolii) in a cool moist environment. I. Pasture production

Abstract The ryegrass endophyte, which has been linked to animal disorders and increased pest resistance of its host in a range of environments in New Zealand, was studied in a field experiment in Southland, New Zealand. In contrast with other (warmer and/or drier) environments, the endophyte was found to have minimal effects on pasture production and composition in years with adequate summer rainfall, but endophyte did suppress clover growth (P = 0.028) under summer drought conditions. There was no difference between endophyte‐infected and endophyte‐free treatments for ryegrass tiller densities, number of clover growing points, total herbage production, herbage composition, and the chemical (elemental concentrations and digestibility) composition of ryegrass. The proportion of endophyte‐infected tillers did not change significantly over a five year period, and peak lolitrem B (1.2 ppm) and ergovaline (0.8 ppm) concentrations in the ryegrass component were lower and the peramine (20 ppm) concentration sim...

Influence of the ryegrass endophyte (Neotyphodium lolii) in a cool moist environment IV. Plant parasitic nematodes

Abstract The influence of the ryegrass endophyte on plant‐parasitic nematodes in a cool moist environment in New Zealand was evaluated in a pot and a grazing experiment. Nematodes of the genus Paratylenchus made up 99% of the fraction of plant‐parasitic nematodes and their numbers were higher (P > 0.05) on endophyte‐free plants in the pot experiment and in fields containing mono‐cultures of endophyte‐free ryegrass. Nui endophyte‐free plants and pastures had higher dry matter yields than endophyte‐infected plants and pastures. The effect of endophyte strains on nematodes was inconclusive.

Comparisons between wild populations and bred perennial ryegrasses for root growth and root/shoot partitioning.

Abstract Root and shoot dry weights (DW), and root DW depth distribution were determ ined for wild type perennial ryegrass, breeding lines and cultivars. The plants were grown in 1 m deep tubes of sand culture in a glasshouse experiment. There were significant differences in shoot DW among accessions in the wild types but not within the bred material, and the wild types had more accessions with low shoot DW. Root DW varied significantly among accessions in both the bred material and the wild types. There were significant differences in root/shoot DW ratios among accessions, and between pools in the breeding lines, but no differences within the wild types. Root/ shoot ratios in the wild types had a much narrower and generally higher range of values than those in the bred lines. The percentage of root DW in the top 10 cm of sand did not vary significantly in the bred lines but it did in the wild types. Variation was recorded in root DW depth distribution at both the accession and genotype levels. We concluded that selection for merit based on shoot performance does not necessarily result in large root systems, and better plant performance might result from an increase in root system size in perennial ryegrass.

Morphogenetic adaptation to defoliation and soil fertility in perennial ryegrass (Lolium perenne)

Abstract Morphogenetic adaptation, plasticity, and mortality of four perennial ryegrass populations, representing different selection histories, were compared in response to soil fertility and to defoliation severity. In a second experiment, morphogenetic adaptation and plasticity in response to defoliation frequency were studied in two divergent sub‐populations. Genetic variability was found between ryegrass populations for leaf appearance and elongation rates, leaf size, and tiller number. All populations exhibited plasticity in response to defoliation severity and soil fertility. There was no genetic variation for plasticity, the morphological response to the environment. Morphogenetic differences between populations remained constant across environments and resulted in differential mortality under the most severe defoliation. Both leaf length and rate of leaf appearance were positively correlated with greater mortality. The ryegrass ideotype for hill country is a compromise between yield and persistence.

Influence of the ryegrass endophyte (Neotyphodium lolii) in a cool‐moist environment III. Interaction with white clover

Abstract White clover was grown together with either endophyte‐free or endophyte‐infected (strain either AR6 or wildtype) Nui ryegrass under four environmental conditions (covering low or moderate temperatures, moist or draughted soil, clippings removed or returned) in a glasshouse experiment. The presence of wildtype endophyte in ryegrass plants had in general, but especially under optimal growing conditions, a significant positive effect (P < 0.05) on white clover stolon length, number of growing points, and the number of nodules. No endophyte effect was observed on the distribution of nodules over root depth, size, and colour classes under any environment. It is postulated that endophyte‐associated compounds in root leachates may have an effect on mycorrhiza, the size of the effect increasing with the level of abiotic stress to which ryegrass plants are subjected.

Plant morphology differences in two perennial ryegrass cultivars

Abstract ‘Grasslands Samson’ and ‘Grasslands Impact’ are cultivars of perennial ryegrass (Lolium perenne L.) widely used in New Zealand. This study investigated differences in vegetative morphology of these cultivars. Seeds were germinated, and 50 seedlings per cultivar assessed for 10 different morphological traits in a greenhouse in spring, up to the 10th leaf stage of growth. The cultivars differed most in mean leaf width, leaf‐sheath length, leaf appearance interval, and tiller number per plant. ‘Grasslands Samson’ had broader leaves, shorter leaf‐sheaths, a shorter leaf appearance interval, and fewer tillers per plant on average than ‘Grasslands Impact’, but with overlap between cultivars in all cases. Principal component (PC) analysis of morphological data yielded four PCs judged to contain biological information. PCs 1 and 2 together explained 63% of data variation and identified individual plants of either cultivar with greater leaf length arising from higher leaf elongation rate or leaf elongation duration, respectively. PCs 3 and 4 discriminated between cultivars. Future studies of this type would benefit from the inclusion of a tiller weight measurement not included here. PC analysis of multiple morphological traits appears to provide a useful tool for interpreting alternate forage grass growth strategies.

Influence of the Ryegrass Endophyte on Phyto-Nematodes

Ryegrass endophyte (Neotyphodium lolii) mediated resistance to Argentine stem weevil (Listronotus bonariensis) (ASW) (Prestidge et al., 1982) proved to be the first of an increasing number of pasture pests against which endophytes provide some level of protection. Latch (1993) lists 24 insect species and 6 nematode species affected by the presence of endophytes of perennial ryegrass and/or tall fescue.