An integral part of the successful breeding program is the selection of elite plants.  This is facilitated through disease screening procedures for mainly Phytophtora root rot and Colletotrichum crown rot.  Conducted by Julie Mackie of the CRCTPP, these procedures are of the highest scientific standard.

The research involves utilising molecular and traditional technologies to understand genetic variation in the pathogens, and using this information to identify plant germplasm with robust and effective resistance.

Recently, PAC701 and PAC901 were developed by Prof Irwin’s team by selecting elite plants from the most adapted lucerne varieties widely grown in Australia.

PAC701 has a group 7 winter activity and is highly resistant to Crown rot caused by Colletotrichum trifolii races 1, 2 and 4.  It is also highly resistant to Bluegreen and Spotted aphid.  It is rated resistant to root rot caused by Phytophthora medcaginis.  The high resistance level to Colletotrichum trifolii race 2 is unique in current Australian varieties.

PAC901 is a highly winter active variety.  It is complemented by resistance to Bluegreen and Spotted aphid, and high resistance levels to Phytophthora.  PAC901 is highly resistant to Colletotrichum trifolii race 1 and 4 and resistant to race 2.

These two varieties with their superior disease resistance packages are envisaged to perform extremely well under high disease pressure, as experienced in heavy soils and under irrigation.

Further development of new lucerne varieties in this collaborative venture will maintain emphasis on disease resistance while utilising genetic resistances from a wide range of global sources in the breeding endeavours.

Plate 1:  Seedling establishment for disease screening

Varieties are grown in a randomized replicated design under controlled environmental conditions in preparation for inoculation with the chosen pathogen.

Plate 2:  Seedling count after inoculation with pathogen

After inoculation and the incubation period, the resistant seedlings can be scored and if desired transplanted to be used for further breeding.

Plate 3:  Plant Breeder’s Rights trial using spaced plants for assessment

New varieties are protected by the Plant Breeders’ Rights Act.  To register a new variety it has to be shown to be distinct from any other known variety, uniform and stable between successive generations.  This is accomplished by conducting a field trial following international guidelines.

Plate 4:  Replicated variety trial assessing forage yield over multiple years

Varieties are trialed in numerous locations around Australia to identify the most suitable varieties for commercial release.