Agronomic trials at cool (Gore) and warm (Palmerston North) temperate sites in New Zealand tested ten United Kingdom-bred (six diploids, four tetraploids) and two New Zealand-bred diploid ('Bronsyn', 'Impact') perennial and long-term hybrid ryegrasses (Lolium perenne, L. boucheanum) over two trial periods. Dry matter (DM) yields and persistence were better at the cool site but differential expression among cultivars for water-soluble carbohydrates (WSC) and yields was small compared with the warm site. The tetraploid cultivars generally had the highest concentrations of WSC but also on occasions had higher levels of crown rust, moderate DM yields and poorer persistence compared with diploids. Two of the tetraploid cultivars will be of value for their high WSC and good agronomic performance at the cool site. Some of the diploid UK cultivars expressed higher WSC and had similar or higher annual DM yields than some of the NZ-bred cultivars, and had high levels of resistance to crown rust. Overall, differences among cultivars in expression of WSC were small. Some differences occurred for seasonal DM yields with some UK cultivars having lower winter yields.

No abstract

Growth of chicory (Cichorium intybus)in mixtures with different companion grass species and white clover (Trifolium repens) was examined over 4 years in a trial rotationally grazed by sheep. A mixture containing red clover (T. pratense) instead of chicory, and ryegrass (Lolium perenne), was also included. Over summer and autumn, pastures were either grazed frequently (every 3-4 weeks) or infrequently (4-6 weeks), and at other times of the year every 4 weeks. Chicory establishment was high (82% of viable seed sown), with 46 plants/m 2 , declining to 15/m 2 by Year 4, whereas red clover plant numbers declined from 101/m 2 to 13/m 2 . Dry matter (DM) yields of chicory and red clover increased from Year 1 to Year 3, then declined in Year 4. Over the 4 years, chicory contributed 34, 80, 85, and 57%, respectively, to green DM yield; red clover contributed 9, 24, 77, and 13%. Yields of sown grass were inversely related to chicory or red clover yields (P < 0.001, r= 0.82), particularly for chicory-based pasture mixtures. Chicory and red clover both displayed a strong pattern of seasonal growth in response to temperature. This distinct pattern of growth for chicory-based pastures was greatest for mixtures with tall fescue (Festuca arundinacea) and prairie grass (Bromus willdenowii), grasses that were lowyielding. In contrast, phalaris (Phalaris aquatica)-chicory pastures had high grass growth in all A95001Received 12 January 1995; accepted 1 May 1995 seasons, resulting in the highest total annual DM yields and a more even seasonal spread of production. Ryegrass-chicory pastures were intermediate and ryegrass/cocksfoot (Dactylis glomerata)-chicory pastures were lower-yielding. Red clover/ryegrass pastures had a more even seasonal spread of production, through greater winter and lower summer yields, than the chicorybased pastures. Frequent grazing significantly decreased DM yields of chicory (-19%), red clover (-61%), and total green herbage (-11%) compared with infrequent grazing, whereas there was no effect of grazing frequency on plant numbers of chicory or red clover.

A set of 18 ryegrass cultivars and breeders' lines, some selected for elevated concentrations of high molecular weight fructan, were compared for forage composition in mown row trials at two sites, in Canterbury and Manawatu. Cultivars varied significantly and consistently, with cultivars selected for elevated high molecular weight fructan showing consistently higher concentrations of these and total soluble carbohydrate, and lower concentrations of crude protein. Keywords: fructan, soluble carbohydrates, protein metabolism, forage quality, ryegrass breeding, cultivars

The yield potential of modern forage cultivars is a limit to production from pasture- based agriculture, and may influence profitability. Hybrid vigour has increased yield in a range of plant species, but is only partially captured in conventional forage breeding systems. The objective of this research was to assess the potential for harnessing hybrid vigour in a semi-hybrid breeding system for perennial ryegrass (Lolium perenne). Paired crosses among eight parental sources, including four cultivars and four ecotypes, were used to create 28 semi-hybrid populations. Parents, semi-hybrids and check cultivars were trialled in pure grass plots under rotational grazing for 2 years in the Manawatu. Dry matter yield data were used to estimate cumulative and seasonal patterns of hybrid vigour expression for cultivar x cultivar semi-hybrid combinations. The mean level of high parent heterosis was less than 2%. However, one combination exhibited significant (p