An evaluation of Ariki ryegrass under Canterbury conditions

Following the success of Corkhill (1945) in producing short-rotation ryegrass (Lolium perenne x Lolium multiflorum) with controlled hybridisation and selection, the Plant Breeding Division of the D.S.I.R. (N.Z.) began a breeding programme to produce a new strain of ryegrass, which subsequently became known as Ariki ryegrass. Ariki was produced as a result of crossing 40 selected perennial ryegrass plants (cultivar Ruanui) with 40 selected short-rotation plants (cultivar Manawa), and the details of its breeding programme have been described by Corkhill (1957). The objective in breeding this variety was that it should have the persistency, dense tillering habit and ability to stand hard grazing of certified perennial ryegrass, associated with earlier spring growth, later flowering, improved palatibility and resistance to leaf rust. Resistance to Argentine Stem Weevil was not intended to be included into the breeding programme although the presence of this insect during selection of plants meant the new strain was at least resistant to some degree of attack. It was anticipated that Ariki would be capable of replacing perennial ryegrass throughout many high fertility areas of New Zealand. Barclay (1963) and Bascand (1963) have reported on the performance of Ariki throughout various trial regions in New Zealand, and it would appear that it is intermediate in growth, between short-rotation and perennial, especially during the first year of establishment. Subsequent work by Bailey (1964) and Evans (1964) suggests that Ariki is more similar to the perennial parentage than to the short-rotation, especially in regard to nutritive quality and lamb fattening ability. In many of the early large-scale evaluation trials, great difficulty had been experienced in maintaining a satisfactory grass: clover balance in the Ariki swards, and, possibly associated with this was some evidence of stock health problems, particularly of low fattening and scouring of lambs. With these aspects in mind an evaluation trial was laid down to investigate the establishment and early management problems of Ariki ryegrass, sown under sward conditions in Canterbury.