Pathogenicity of Fusarium equisetiand Colletotrichum graminicolaon barnyardgrass and rice genotypes by biplot analysis

Barnyardgrass (Echinochloa spp.) is the most important weeds in rice fields. Funguses species play important roles in biological control of the weeds, especially Echinochloain rice fields. In this research, Fusarium equiseti and Colletotrichum graminicola were isolated from E. oryzicolaandE. crus-galli and their pathogenicity effects were compared on these weeds and five rice genotypes in a completely randomized design with three replications. Two net fungi were inoculated on weeds and rice genotypes using a spore suspension consisting of 106 spore·ml-1 of distilled water. Genotype-by-pathogen biplot analysis was down for illustration of pathogenicity of two fungi (as pathogen) on host genotypes to facilitate the simultaneously visualization of relationship among pathogens and genotypes.The significant effects of pathogens were observed on disease rate and reduction of plant height, dry and fresh weight of plantlets. Biplot analysis indicated a differential interaction between pathogens and rice and Echinochloa genotypes for the studied traits. Average-tester-coordination (ATC) view of biplot indicated that Sepidroud and Binam were as the most sensitive and tolerant genotypes to two mentioned fungi according to their disease rating. The relationships view of biplot indicated there were higher positive correlations between diease rate and reduction in plantlet dry weight. Hashemi cultivar located near the biplot origin and had a horizontal resistance to fungi and can be used to biological control of barnyardgrass in the filed of this cultivar. In conclusion, the results of this study based on the severityof the disease showed thatC. graminicolafungus had more antagonistic effectsthanF. equiseti, especialy on E. crus-galli.