Partial resistance to Septoria glycines in soybean

Abstract

Screening of soybean (Glycines max) genotypes resistant to brown spot was performed under greenhouse conditions by inoculating one-month-old plants with a suspension of spores, calibrated to 10(6) spores/ml. Evaluation was based on the area under the lesion progress curves, level of chlorosis, and period to reach 5% severity, starting two weeks after inoculation. No cultivar was resistant to brown spot. However, cultivars CTS-40, IAS-2, IAS-5, PI 230 975, and PI 204 332 exhibited less infected leaf area and a longer period to reach 5% disease severity. The results showed that the level of severity established based on the number of days to reach it is a good indicator for screening soybean genotypes with partial resistance to S. glycines. Genotypes identified as tolerant in this work may be used in soybean breeding programs in Brazil.