Soybean (Glycine max) is one of the most produced and consumed grain legumes worldwide. According to the United States Department of Agriculture, almost 363 million tonnes were produced in the 2020/2021 season globally, with a harvested area of almost 128 million hectares (USDA, 2021). Brazil, the world's largest producer of the grain, had its productivity evaluated at 3517 kg/ha (CONAB, 2021). The importance of soybean cultivation is related both to nutritional factors, such as its high protein content (approximately 40%), and its considerable oil content (about 20%), which is used for human and animal consumption and biodiesel production.

Soybean is one of the most produced and consumed grains worldwide. Brazil, the world's largest producer of the grain, represents around 50% of the national grain production (Conab, 2021). Among the main causes of crop losses are diseases caused by pathogens that infect seeds, such as Colletotrichum truncatum, Corynespora cassiicola, Sclerotinia sclerotiorum and Rhizoctonia solani.The fungicides used are not totally effective in controlling these diseases, requiring new options with less impact on the environment. Photodynamic Inactivation (PDI) may be an alternative. PDI consists of the use of a photosensitizer (PS), which absorbs light and, by transferring energy or electrons, excites oxygen molecules, generating free radicals and reactive oxygen species (ROS). These cytotoxic species can then damage cellular and death of biological targets. Porphyrins and their derivatives are FS molecules and can be used in PDI.The aim of the present study was to evaluate the efficiency of PDI in the photoinactivation of C. truncatum, C. cassiicola, S. sclerotiorum and R. solani, using a mixture of cationic meso-tetra-aryl porphyrins as PS.