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Breeding ryegrass for reduced inorganic phosphorus (Pi) concentrations in leaf vacuoles could lower pasture P fertiliser requirements with economic and environmental benefits. We investigated foliar Pi% accumulation characteristics of a range of ryegrass cultivars and ecotypes in glasshouse experiments, and ryegrass cultivars from two field trials. Pi in ryegrass was also compared with Pi in cocksfoot, tall fescue, prairie grass and Phalaris in a glasshouse experiment. Pi expressed as a percentage of leaf total phosphorus was higher (average 82.5%) in the older ryegrass cultivars – Ruanui, and Nui and the New Zealand hill country ecotypes (85%) than in more recently bred cultivars like Aberdart and One50 (74.7%). In the other grass species, foliar Pi% was lowest in prairie grass, intermediate in tall fescue with the highest values in cocksfoot, Phalaris and ryegrass. The results suggest that including a lower Pi concentration in future ryegrass breeding programmes might improve ryegrass P use efficiency without compromising growth rates. [ABSTRACT FROM AUTHOR]

Concentrations of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), selenium (Se) and iodine (I) were measured in chicory (Cichorium intybus L.) plants previously selected for either high or low foliar cadmium (Cd), and progeny lines from crossings within the high and low Cd populations. Micronutrient levels were lower and more variable, with the exception of Se, in the low Cd progeny plants compared to the parental levels but the concentrations of Fe, Mn, Zn, and I still met or exceeded grazing animal requirements. This means that breeding for low Cd chicory does not pose an immediate risk to the animal's micronutrient nutrition for these elements. Cobalt and Se in the low Cd progeny lines were lower than the recommended levels for New Zealand pastures to sustain animal health but the population size sampled was relatively limited and there may be more variation contained in a larger population. Concentrations of both these micronutrients should be monitored in any breeding programme for low-Cd chicory. This would allow plants with the highest shoot concentrations of both elements to be used. [ABSTRACT FROM AUTHOR]

We tested whether selection of ryegrass for reduced root hair length and density would reduce root competition on white clover for phosphate (P). A Rhizosheath Selection Tool was used to select two ryegrass populations with contrasting root hair traits. These were grown at five soil P levels in a glasshouse experiment and rhizosheath trait selection had no effect on growth or shoot P concentrations. The ryegrass populations were also grown with white clover in soils with Olsen P12 or 19 mg L−1. In the Olsen P12 soil, clover grown with the smaller rhizosheath ryegrass had significantly heavier shoots and contained more P than clover grown with the larger rhizosheath ryegrass. In the Olsen P19 soil differences in ryegrass rhizosheath had no effect on clover growth. The results showed that under the experimental conditions, grass-clover competition for soil P could be modified by the rhizosheath traits of ryegrass. [ABSTRACT FROM AUTHOR]

Fifty plants from each of eight chicory (Cichorium intybus L.) populations were screened for foliar cadmium (Cd) concentrations using soil containing 1.2 mg Cd kg−1. There was substantial variation in Cd concentrations in all the populations and no relationship between Cd level and plant size. Two polycrosses were done with plants selected for lower Cd and one polycross with plants selected for higher Cd, and the progenies tested for foliar Cd and growth rate. Progenies from parents selected for higher Cd averaged 15.1 mg Cd kg−1 and the progenies from those selected for lower Cd averaged 8.1 mg Cd kg−1. The % realised heritabilities for shoot Cd concentrations ranged from 0.6 to 1.0. This means that it should be possible to breed productive, low Cd chicory for use as a forage on soils with elevated Cd, as well as hyper accumulating types for phytoremediation of contaminated soils. [ABSTRACT FROM AUTHOR]

Herbage accumulation (HA) data from four sites were combined to (1) address the hypothesis that adjustments to the New Zealand Forage Value Index to account for grass-clover interactions are not required and (2) explore the main effects of clover and nitrogen (N) fertiliser treatments on pasture productivity. In summer and autumn, pastures based on mid-season heading ryegrass cultivars consistently supported a greater clover content than pastures based on late heading cultivars. However, the clover ×  cultivar interaction was significant in only 2 of 17 HA data sets available for analysis. Thus, the hypothesis is supported. Compared with ryegrass monocultures, mixtures yielded an additional 2.4 (in the Low-N treatment) and 1.2 (High-N treatment) t DM/ha/year. Apparent N transfer from clover to grass was 79 (Low N) and 27 (High N) kg N/ha/year, derived from estimated N fixation efficiencies of 66 (Low N) and 50 (High N) kg N/t clover DM grown. [ABSTRACT FROM AUTHOR]

Concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, sulphur and sodium were measured in eight perennial ryegrass cultivars grown at four sites in New Zealand (Waikato, Manawatu, Canterbury and Southland). For the macronutrient analyses, herbage samples were collected from pure ryegrass plots, grown with two nitrogen fertiliser rates, with three sites sampled in autumn (April/May) and all four sites in spring (October/November) of 2013. There were significant differences among the cultivars for all elements except potassium, extending the results of earlier research to contemporary commercial cultivars. It is suggested that breeding ryegrass for lowered shoot phosphorus concentration should be prioritised because of the economic and environmental benefits to be gained from farming with reduced phosphate fertiliser requirements. [ABSTRACT FROM AUTHOR]

The development of economic indexing systems for ranking cultivars of forage species requires new knowledge of factors that may influence the scaling of agronomic data collected in controlled, small-plot evaluation trials to whole farm systems. In the case of perennial ryegrass indexing, one such knowledge gap is the effect of growing clover with ryegrass on the relative rankings of different ryegrass cultivars. The objective of the investigation reported in this series was to test whether the relative yield rankings of perennial ryegrass (Lolium perenne L.) cultivars representing the range in phenotypes now available to New Zealand farmers as a result of recent breeding differed when those cultivars were grown in monocultures (as per standard protocols for cultivar yield trialling systems such as the National Forage Variety Trials) versus mixtures of grass and clover. This paper presents the rationale for the investigation by reviewing developments in perennial ryegrass breeding and evaluation in the context of grass-clover relationships in grazed pasture systems. The papers that follow report results from a multi-year, multi-site investigation comparing the yield, nutritive value and other productivity-related variables of eight perennial ryegrass cultivars grown with or without white clover (monoculture versus mixture respectively) at two levels of nitrogen fertiliser. Key considerations in the design of the experiment on which the investigation was based are discussed. [ABSTRACT FROM AUTHOR]