Methods of inoculation and effects of Fusarium oxysporum f. sp vasinfectum in cotton seeds

The availability of seeds infected by fungi or other pathogens transmissible by this way is important for several purposes. This work was conducted to evaluate proceedings of inoculations and period of exposition of seeds to Fusarium oxysporum f. sp. vasinfectum through the water restriction technique. The following methods were compared: (1) seed immersion ill a conidial suspension (10(6) conidia/mL) following incubation ill Substrate with all osmotic potential of -1.0 MPa; (2) atomization of a conidial suspension (10(6) conidia/mL) upon the Substrate and on the seeds, and (3) direct contact of the seeds with the fungus mycelium, grown upon the Substrate. All methods enabled to obtain seeds with different inoculum potential equivalent to different times, 24, 49, 72, 96 and 120 hours of seed expositions to the fungus. To evaluate the efficacy of infection, germination tests oil roll paper and in soil/sand substrate and Blotter Test were applied. The most effective method was the immersion of seeds in inoculum suspension followed incubation ill Substrate with water restriction. The period of time that seeds should stay in contact with the pathogen, without affecting their physiological quality, was 53 h to 57 h.