The integrated combination of plant breeding and agronomic research has a long and impressive record of generating increased crop productivity. These gains have to a large extent been limited to the major crops such as wheat, maize and rice and less so in crops like sorghum.
Unfortunately, productivity gains in sorghum have tended to be low due to a range of factors including the low investment in the crop and the fact that sorghum is typically grown as a dryland crop in highly variable water-limited environments. Some have even suggested that the crop is inherently low yielding. However, given appropriate resourcing substantial productivity gains can be achieved. For example, a recent study showed productivity gains in Australian sorghum have averaged between 2.5 to 3.9% per annum for the last 30 years. These gains have been achieved by effective conventional crop breeding and agronomic research. Given its tolerance of drought, poor fertility, and high temperatures sorghum has an important place in the cropping systems of the 500 million resource-poor farmers. Changes in climate have the potential to further increase its importance as a food security crop. Together these factors make the issue of improving productivity gains critical for the food security of large numbers of resource-poor smallholder farmers, particularly in Africa.
While the productivity gains achieved in Australia provide considerable hope for the potential to make productivity gains in African sorghum, such approaches tend to be context dependent and require effective well-coordinated crop improvement programs in the target environment. In Africa, there is a critical need to strengthen and integrate local crop improvement efforts particularly given the opportunities presented by genomic selection using whole genome scans, advanced statistical methods, novel selection methods, and crop simulation. However, effective implementation of these new methods requires an effective conventional plant breeding program. Poor implementation of these technologies in small-scale breeding programs can be worse than no implementation as it may result in limited resources being re-directed from other breeding activities without sufficient return.
In a proof of concept project, the Bill & Melinda Gates Foundation and the Australian Center for International Agricultural Research have funded a team of Australian and Ethiopian crop improvement specialists to improve sorghum breeding in Ethiopia. The project, titled integrated Methods for Accelerating SorgHum Improvement in LowLand Agroecologies (iMashilla), has focused on the redesign of the breeding pipeline and the implementation of well-tried breeding technologies such as packet printing, barcoding, efficient statistical designs and electronic data capture devices which have enabled the Ethiopian Institute of Agricultural Research (EIAR) breeding program to make a step change in its breeding capacity. The program has increased its first stage of yield testing more than tenfold from 36 to 430 varieties and increased the number of phenotypic data points to >200K data points being captured electronically per season. The heritability of yield in breeding trials was increased by between 30 to 50 % and the time from crossing to release is set to decrease by two years. Such changes should result in substantially increased rates of genetic gain, and have been achieved largely through the provision of appropriate equipment and training and relatively small increases in manpower and consumables. The program is now in a strong position to capitalize on new technologies such as genomic selection and near infra-red spectrophotometry (NIR).
The iMashilla project has demonstrated the potential to greatly raise the capacity of national breeding programs to make use of new technologies and deliver high levels of genetic gain. The next step is to expand this success to other breeding programs and build the systems and funding to build and sustain the infrastructure and skills in national breeding programs.
Author: Professor David Jordan