Screening Moroccan Barley (Hordeum vulgare L.) Accessions for Resistance to Crown Rot Caused by Fusarium culmorum and Selection of Key Assessment Variables

Crown rot caused by Fusarium culmorum is a major fungal disease in cereal crops, particularly wheat and barley, with widespread occurrence in cereal-growing regions worldwide. Its prevalence is increasing in arid and semi-arid zones, where it leads to significant yield and quality losses, threatening food security and the economy. The objectives of this study were twofold: first, to identify a precise, rapid, and practical method for evaluating crown rot severity, and second, to assess the genetic resistance levels in a collection of barley (Hordeum vulgare L.) accessions using the selected method. A total of 100 barley accessions from the GeneBank of INRA Morocco were sown and inoculated with an organic inoculum of F. culmorum in a completely randomized block with four replications. Several variables were measured, including root severity index, internode severity, total number of spikes, number of sterile spikes, plant height, dry biomass weight at flowering, and biological yield. The principal component analysis (PCA) revealed that internode severity and the percentage of sterile spikes are the most reliable indicators, as they reflect both the pathogen's progression within the plant and its direct impact on yield loss. Crown inoculation was also validated as a reliable screening method. Six accessions were identified as resistant and ranged from high to moderate performance levels. In addition, nine accessions were classified as tolerant, and one displayed resistance but had a low agronomic performance. These indicators and accessions provide practical tools for breeders, as they can be directly integrated into selection programs to develop barley varieties resistant or tolerant to crown rot, thereby supporting sustainable cereal production. These selected accessions represent valuable genetic material that could be used by breeders to develop varieties resistant or tolerant to crown rot caused by Fusarium culmorum.