May 2005: One of the biggest breakthroughs in grain sorghum breeding was made with the release of MR-Buster by Pacific Seeds.

Pacific Seeds sorghum breeder Neil Muller, was a key figure responsible for breeding this benchmark sorghum. It has been the yardstick for other sorghum varieties for 15 years. “Breeding a grain sorghum that incorporates stress tolerance, wide adaptation and above all the ability to produce good yields, both top end and under less favorable conditions, is a time consuming process” Mr Muller said.

The development of new hybrid combinations is only part of the process involved in the discovery of well adapted sorghum varieties. Yield testing to ensure the new hybrids perform at the highest level is an absolute necessity prior to commercially releasing them.

Pacific Seeds' rigorous commitment to this part of the development procedure has been instrumental in allowing the release of elite hybrids such as MR-Buster, MR43 and MR-Maxi.

“We don’t fast-track our experimental hybrids into the market place. We must be absolutely sure that they perform at a high level across a range of seasons and environmental conditions,” Mr Muller said.

While farmers see the breeders’ end product at planting time, few besides those in the industry realise the process a variety must go through, to make the cut for commercial release.

“The aim of plant breeding programs is to develop new genetic combinations that give the plant breeder an opportunity to identify improved varieties for enhanced performance and broad adaptation to the target group of environments,” Mr Muller said.

In the case of grain sorghum these target environments encompass a broad area, from the Liverpool Plains in NSW through to Central Queensland.  Identifying the genetic combinations that work across this broad range is a major task.

 “The need for trialing is essential to sort out the response (performance) of the different genotypes to these target environments,” he said.

“Not all genotypes respond in the same way to the different environments and the only way to determine which ones are broadly adapted is to test these new combinations in all key environments.”

These trials are rigorous, ensuring only the best make it through.

Advancements are undertaken using scientifically founded methods and statistically robust analytical procedures.

“Pacific Seeds' Grain Sorghum Breeding Program considers the hybrid evaluation system to be central to the success of new hybrid releases and, therefore, the success of grain sorghum producers in Australia,” Mr Muller said.

For this reason the program has a very strict testing protocol in place to allow for the release of hybrids that perform at only the highest level.

“The testing system has been an integral part of Pacific Seeds ability to, and success in, delivering only the elite of the elite. e.g. MR-Buster, MR43, MR-Maxi.”

After new line development is achieved using traditional plant breeding methods, new experimental hybrid combinations are increased in the breeding nursery.

“Approximately 1500 new combinations are entered in the testing system per season and a further 1000 hybrids are retested in the initial level of testing.”

“This set of 2,500 hybrids is sown in two locations as single row, unreplicated plots with one location in Southern Queensland and the other in Central Queensland. A modified augmented trial design is used to give a degree of statistical accuracy to these trials.”

“As an initial test this is a very effective way to reduce numbers quickly. After one to two seasons testing at this level, 10 percent of the initial numbers are advanced to the second level for more detailed trialing.”

At this level trial designs have greater statistical robustness and the techniques of randomisation and replication are used. All of the experimental hybrids in this level are compared with a standard set of check varieties, namely MR-Buster, MR43 and MR-Pacer. In addition other commercial hybrids are included to allow a completely balanced view of the results.

“Fifteen locations across the key environments are established each season with each entry appearing in at least 10 locations, five locations are sown across the Darling Downs, three in Northern NSW, two on the Liverpool Plains and five in Central Queensland,” Mr Muller said.

“Hybrids at this level can remain here for two to four seasons before advancing or dropping out and results from these trials allow the advancement of the top five percent to the third level of testing.”

This third level is a smaller set of entries but is sown at all 15 locations. At this level decisions are made after two seasons to advance or drop the hybrids.

“Upon advancement, the hybrids are increased in greater quantities for entry into the larger "Farmer Trialing" system.”

“This step in the system is critical to the release decision making process and only hybrids performing at the highest level are considered for release.”

So next time the decision to purchase grain sorghum seed comes round, it’s wise to consider the processes the hybrid has gone through before it hits the farmer’s field.