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Perennial ryegrass improvement for temperate pastures in Australia

P.J. Cunningham, M.W. Anderson, R.G. Clarke, D.R. Eagling, O.N. Villalta

Department of Agriculture, Pastoral Research Institute, Hamilton VIC 3300
Department of Agriculture, Institute of Plant Sciences, Burnley VIC 3121

Perennial ryegrass (PRG), Lolium perenne is one of the most important pasture grass in Australia. The naturalised ecotypes, Victorian and Kangaroo Valley, and cultivars developed in New Zealand are the main ones sown. In 1989 an integrated program wa initiated to improve PRG with the aim of producing cultivars with varying maturity, improved seasonal growth, drought tolerance, resistance to diseases and pests and enhanced nutritive value (2).

Methods

Three breeding sites were selected in south-west Victoria, Balmoral with annual average rainfall of 610 mm (marginal climate), Hamilton with 710 mm and Timboon with 900 mm. Breeding populations for three breeding objectives namely (i) improved autumn growth and drought tolerance, (ii) improved winter growth, and (iii) improved late season growth were established as 0.5 m-spaced plants or replicated 1.0 m drill rows. Recurrent selection programs comprising three phases have been adopted. The first characterisation phase includes visual rating (0-9) over two seasons, for seasonal growth, incidence of field disease, habit, and heading date. Phase two comprises screening superior agronomic plants for resistance/susceptibility to crown rust (Puccinia coronata), stem rust (Puccinia graminis) (1), barley yellow dwarf luteovirus (BYDV) and ryegrass mosaic polyvirus (RMV). Phase three includes progeny testing of selected half sib families at several field locations and detailed parent characterisation followed by the selection of parents for synthetic variety formation.

Results and discussion

A population of 320 plants has been selected from material in objective (i) located at Balmoral in 1990 and half sibs produced in 1991. This material has a high degree of summer dormancy and has proved to be the most persistent of any material tested to date. For objective (ii) plants were selected at Balmoral and Hamilton for winter growth in the second year of characterisation. Half sib families from this population have been sown at all three breeding locations, and at Bunbury, WA and Flaxley, SA. Crown rust screening of selected plants at Burnley has demonstrated variable resistance to five isolates compared to standard cultivars. Results from the BYDV screening have identified lines which appear to be resistant. These lines along with those identified as resistant to crown rust are considered to have significant potential in the breeding program and will undergo further evaluation. Characterisation of a range of late maturity material from New Zealand is continuing at Timboon. Elite families will be identified in 1991 and 1992 to enable formation of synthetic cultivars.

References

Clark, R.G. and Cunningham, P.J. 1991. Proc. 8th Aust. Plant Path. Soc. Conf., Sydney. p. 33.

Cunningham, P.J., Rowe, J.G. and Anderson, M.W. 1990. Res. Rev. Past. Res. Inst., Hamilton 1989/90. pp. 16-19.

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