Rapid test for detection of imidazolinone resistance in sunflower ( Helianthus annuus L.)

Abstract

The development of imidazolinone (IMI) resistant sunflower cultivars represents a great advantage in controlling weeds. The aim of this study was to evaluate the response of sunflower genotypes to the presence of IMIs in a soil-less bioassay. Six genotypes differing in IMI resistance were planted in pots filled with perlite and watered with different imazapyr doses. Differences among resistant, intermediate and susceptible genotypes were observed 8-15 days after planting. The susceptible genotype showed stunted plantlets. The intermediate genotypes developed reduced lateral roots when exposed to imazapyr. The resistant inbred line was only affected at the highest herbicide concentrations. Differences in aerial growth were also observed among genotypes. The bioassay described in this study is a rapid, simple and cost-effective method for early screening herbicide resistant genotypes. This diagnostic test could be a useful tool when breeding for IMI resistance in sunflower.