Tetrazolium test to assess viability and vigour of tomato seeds

Alternative procedures for the tetrazolium (TZ) test to determine viability and vigour of tomato (Lycopersicon esculentum Mill.) seeds were studied in this research. In the first phase of work, four lots of cv. Bruna were hydrated between moistened paper towels (3 h at 40°C and 45°C) followed by staining for 1, 2 and 3 h in a 0.075% tetrazolium chloride solution at 40°C. Viability TZ results were compared to percent germination, seedling emergence and the standard procedure for the TZ test described in the Rules for Seed Testing. In the second phase, viability and vigour (seeds classifi ed in three TZ categories) were determined after preconditioning for 3 h at 45°C and staining for 1, 2 and 3 h at 40°C for three seed lots each from cultivars Debora Max and Acclaim. Results were compared to germination, seedling emergence, saturated salt accelerated aging and controlled deterioration tests. In general, seeds exhibited adequate TZ staining patterns when seed moisture content attained at least 45%. The TZ test provided consistent data for the assessment of viability and vigour of tomato seeds. The results also indicated that reducing the preconditioning period is feasible and represents an important advance permitting faster decisions in seed quality control programs.