Sorghum Breeding Program at ICRISAT

ICRISAT’s sorghum breeding research is committed to strengthening breeding schemes, maximizing heterosis and enhancing genetic gains in the drylands.

File photo. Photo: Srujan P, ICRISAT

The Deputy Director General-Research (DDG-R), Dr Arvind Kumar participated in a field visit to discuss the ongoing open-field research in sorghum breeding at the International Crops Research Institute for the Semi-Arid Tropics headquarters. The visit focused on sorghum breeding nurseries and crossing block, Leasy Scan facility, and entomology and phytopathology experiments.

ICRISAT’s sorghum breeding team aims at research to increase accuracy and genetic gain.

Breeding schemes are customized across all market segments (post-rain, rain, forage, sweet sorghum/high biomass sorghum) and hybridity testing (QC) is systematically performed in F1s, which helps discard false hybrids early on.

Testcross, early yield trial, disease and pest screening are systematically carried out in F6 to predict the performance per se and the values in hybrid combinations (GCA, SCA) of the future fixed inbred lines; for GCA, yield potential is the primary trait of interest.  Dr Ephrem Habyarimana, principal scientist-sorghum breeding team, ICRISAT said, “Testing GCA in early generations helps in producing superior hybrids while saving time and money.”

Harnessing heterosis is another important factor for sorghum production. It is a known fact that performance of parental lines per se is not consistent with the hybrid performance i.e., elite parents don’t necessarily give rise to excellent hybrid varieties. ICRISAT’s Sorghum breeders therefore, judge parents by their potential to produce superior hybrids, not only by their performance per se.

Single Seed Descent Selection (SSD) is also implemented in order to speed up breeding cycles. This is one possible way of alleviating food scarcity problems and enhancing food security. This is the only method where only one seed from F2 population grows on to F3 and the process is repeated in the next generations and up to F5/6, when plants approach a high level of homozygosity.

Interestingly, as a single seed per plant is required in early generations, these can be grown in a small area i.e., greenhouses and rapid generation cycling facilities, which shortens time from seed to seed, allowing to produce more than one generation in a year.

At F6 several research events are simultaneously handled.

• Single plant selection is operated to advance the recombinant inbred lines (RILs) to F7
• Early yield trial is initiated to evaluate the RILs performance per se
• Testcrossing (line x tester design) is carried out to assess the RILs values in hybrid combinations
• RILs’ seeds are shared with phytopathology, entomology, and physiology scientists for pest/disease resistance screening and physiological and quality assessment.

The information gathered during the above steps cannot be overemphasized. It allows discarding poor materials prior to producing F1 hybrids and conducting the multilocation trials (MLTs). Elite RILs with high performance per se are considered for further testing through MLTs for developing superior line varieties, while selected lines with high combining ability are used in “A x R” crosses to develop F1 hybrids that undergo planned testing in collaboration with our partners in the process of hybrid cultivar development. The evaluated General Combining ability (GCA) is also used to build heterotic groups for downstream breeding applications.