Rapid Ragi: A speed breeding protocol for finger millet.

Background: Climate change is gradually increasing demand for resilient, nutritious crops like finger millet or ragi. Ensuring food security requires researchers to develop improved and adapted cultivars rapidly. Modern techniques such as genomics-assisted breeding have emerged in the previous decade and combined with rapid generation advancement they will offer a step change in the speed of cultivar development.

Results: In this study, we developed a repeatable and cost-effective speed breeding protocol for finger millet by modulating the agronomic and physiological components for early generation advancement. A photoperiod of 9-hours, 29 ± 2℃ temperature, 70% relative humidity, 105 plants per 1.5 sq. ft., 0.17% Hoagland's No. 2 solution spray, restricted irrigation and harvesting at physiological maturity successfully reduced 28-54 days across the maturity groups of finger millet. The advantage was validated in segregating populations confirming up to 4-5 generations a year, instead of 1-2 under field conditions.

Conclusion: The speed breeding protocol developed reduces the breeding cycle time significantly allowing increased genetic gain. The protocol provides the advantage of rapid development of recombinant inbred lines (RILs), high-throughput phenotyping for biotic and abiotic stresses, and genotyping for early generation selections.