Morphophysiological variation, vigor test, and influence of light and temperature on the germination of four cultivars of Glycine max (L.) Merrill

Soybean (Glycine max. (L.) Merrill) is a crop whose productivity depends on the quality of the seeds used. In this context, the objective of this study was to characterize the seeds physically, evaluate viability using tetrazolium, identify physiological vigor through an electrical conductivity test, and determine the influence of temperature and photoperiod on the germination of four cultivars (Ultra, Olimpo, Extrema and Foco). 200 seeds were used, measuring size, weight of a thousand seeds, moisture content, and fresh mass. In tetrazolium (1%), 100 seeds were soaked for 4 h at 25°C. For electrical conductivity, 50 seeds were submerged on 75 mL of deionized water at 25°C for periods of 4, 8, 12, 16, 20 and 24 h. In the germination process, the treatments (four replications of 50 seeds) were incubated (B.O.D.) at temperatures of 25°C, 27°C, 30°C and 35°C, under photoperiods of 12 and 14 h. The experimental design adopted was completely randomized for all experiments, and the means were subjected to analysis of variance and Tukey's test at 5% probability. The Ultra cultivar presented perimeter (38.21±3.72 mm), length of 9.98±0.24 mm, and width of 7.94±0.27 mm. The cultivars presented viability above 90%. For electrical conductivity, the 12 h period was effective for identifying vigor. The Ultra cultivar (25°C and 12 h of photoperiod) achieved 77% germination, 10 germinated seeds per day, an average germination time of 4 days and 43 germinated seeds by the third day.