EVALUATION OF 7 ITALIAN AND HYBRID RYEGRASSES UNDER SHEEP GRAZING IN SOUTHLAND, NEW-ZEALAND

Three Italian and four hybrid ryegrass cultivars (Lolium multiflorum a nd L. boucheanum Syn. L. hybridum) sown with the white clover cultivar Grasslands Huia (Trifolium repens), were evaluated under frequent/har d grazing or infrequent/lax grazing. Dry matter (DM) yields and specie s composition were assessed for 5 1/2 years. Ryegrass tiller and white clover growing point population densities were determined annually, a nd leaf:stem ratios every spring and autumn. Ryegrass tillers were ass essed for infection with an Acremonium-like endophytic fungus and bact erial wilt disease (Xanthomonas campestris pv. graminis). The Italian ryegrass cultivars Moata and Concord had total yields 33% greater than the mean of the other cultivars (1800 kg DM/ha) over the first autumn and winter. The Italian cultivars persisted well for 3 years, except Concord which had a high incidence (34%) of bacterial wilt. Of the hyb rid ryegrasses, cultivar Corvette had high ryegrass yields in the firs t year (9800 kg DM/ha), similar to those of the Italian cultivars, and continued to be high-yielding and persistent throughout the experimen t. However, its degree of aftermath heading was high and probably redu ced ryegrass herbage quality in summer and autumn. An inverse relation ship between ryegrass yield and white clover yield resulted in few sig nificant differences in total yields between cultivars. Infrequent/lax grazing maximised total annual yields (+5%) but decreased white clove r yields (-13%). With the importance placed on achieving high white cl over growth in the cool temperate environment of Southland, choice of ryegrass cultivar should consider factors such as pasture quality (pri marily percentage composition of white clover), tolerance of the culti var to a range of grazing managements, and seasonal herbage production . The presence or absence of endophyte was not considered a major fact or influencing the long-term persistence or productivity of the cultiv ars evaluated at this site.