Rapid generation cycling of an F 2 population derived from a cross between Lens culinaris Medik. and Lens ervoides (Brign.) Grande after aphanomyces root rot selection

Cultivated lentil ( Lens culinaris Medik.) is susceptible to aphanomyces root rot ( ARR ), whereas partial resistance is present in wild lentil including Lens ervoides (Brign.) Grande. Approximately six generations of selfing are required to fix a desired trait in a population, which usually requires 2 years in a breeding programme, so the primary objective was to develop a rapid generation cycling ( RGC ) technique that achieves this goal in 1 year. Rapid generation cycling was then tested on an F 2 population ( LR ‐59) derived from a L. culinaris  ×  L. ervoides cross in combination with a reliable ARR screening technique, which generates a wide range of disease severities conducive to selection. Phenotyping of an F 2 population of more than 1,200 plants resulted in scores ranging from 2.4 to 4.0 on a scale from zero to five. Plants with scores lower than 4.0 were selected for advancement for five generations using a modified single‐seed descent method, optimum growing conditions, 20‐hr photoperiod and harvest of immature seeds. Seeds were germinated in a 100 μM gibberellin solution. Average generation length after phenotyping was 56 days resulting in five generations within approximately 300 days. Using a modified inoculation protocol, ARR phenotyping of the F 7 population resulted in scores ranging from 1.4 to 4.0. This inexpensive, nonsterile speed breeding protocol saves 1 year in the development of lentil varieties with improved ARR resistance.