Evaluation and selection of sources of resistance in popcorn to southern corn leaf blight

Southern corn leaf blight (SCLB), caused by Bipolaris maydis, is an important leaf disease of popcorn. The use of resistant genotypes is the most suitable control option for this disease, but there are few sources of resistance described in popcorn germplasm for use in breeding programmes. This research aimed to identify new sources of resistance in a panel of popcorn inbred lines. A total of 184 lines were evaluated in the field twice a year for the incidence and severity of SCLB symptoms. A set of candidate lines for sources of resistance (CLSR) was selected and evaluated in a greenhouse under artificial inoculation based on joint analysis of variance and grouping of means. Data from the area under the disease progress curve (AUDPC), based on three symptom severity assessments, allowed the analysis of variance followed by the grouping of means. The lines presented high phenotypic variability for the incidence and severity of SCLB under field conditions, enabling the selection of lines with higher potential for resistance. The test of means for AUDPC in the greenhouse allowed the formation of five groups, with the highest resistance comprising 23 lines. This group gathered lines with resistance to SCLB, the potential for grain yield and expansion capacity, in addition to lines that stood out with satisfactory performance as parents in previous research. Twelve percent (23 lines) out of the total evaluated lines were indicated as a source of resistance to SCLB.