Identification phénotypique des champignons d’altérations des semences de sésame (sesamum indicum l.) et étude de leur sensibilité aux attaques de sclerotium rolfsii et d’aternaria sp.

Sesame (Sesamum indicum L.) is an important oilseed crop that, valued for its edible seeds, could serve as a genuine source of income for farmers. However, its cultivation is threatened by numerous pathogens which limit its yield. This study aims to improve sesame crop productivity by identifying pathological constraints affecting the agronomic performance of farmers' seed varieties from a major production area in Côte d’Ivoire. Sesame samples were collected from producers in ten villages. The pH and moisture content of these seeds were determined. Seed-deteriorating fungi were then identified, and sensitivity tests against Sclerotium rolfsii and Alternaria sp. were conducted. The results obtained revealed that seed moisture content ranged from 1.45% to 5.82%, with a slightly acidic pH ranging from 5.24 to 5.91. Three fungal spoilage species were isolated from the seeds as epiphytic microflora, namely Aspergillus sp. (66.6%), Alternaria sp. (50%), and Sclerotium rolfsii (25%), whilst four (4) fungal species were identified in the endophytic microflora, namely Aspergillus sp. (50.67 per cent), Mucor sp. (30%), Phoma sp. (13.33%) and Penicillium sp. (06%) were isolated from the seeds. With regard to susceptibility tests, the plants grown in holes inoculated with Sclerotium rolfsii and Alternaria sp. showed symptoms of disease, unlike the control plants, which appeared healthy. The average weight of 1,000 grains was 2.51 g for the control plants and 1.31 g for the inoculated plants. The control plants produced an average of 16 grains per capsule, compared with 7 grains and 6 grains for plants inoculated with Sclerotium rolfsii and Alternaria sp. respectively. Plants inoculated with Alternaria sp. and Sclerotium rolfsii produced an average of 21 and 19 capsules respectively, compared with an average of 42 capsules for the controls. Furthermore, accessions A4 and A5 were the least susceptible to attacks by Sclerotium rolfsii and Alternaria sp., respectively.