Influence of different priming and drying methods on the germination of tomato seeds at different temperatures

Priming is a technique used to harmonize the germination of seeds, even under adverse conditions such as cold. We evaluated the effects of osmotic solutions, incubation times and drying speed on the physiological quality of tomato seeds. The osmotic solutions were used in the following proportions: 100% PEG 6000 (polyethylene glycol); 25% PEG + 75% KNO3 (potassium nitrate); 50% PEG + 50% KNO3; 75% PEG + 25% KNO3; and 100% KNO3, all with osmotic potential of -1.1 Mpa. The PEG 6000 solution had a concentration of 0.05M and the KNO3 solution had a concentration of 0.22M. Unprimed seeds were used as controls. The objective was to assess the effects of different priming and drying methods on the initial development of the seeds at low and ideal temperatures. The parameters measured were germinability (G%), mean germination time (MGT) and mean germination rate (MGR), at two temperatures, 25 °C and 17 °C. The priming promoted reduction of the MGT and increase of the MGR in comparison with the control seeds at both temperatures. The treatments with the three highest concentrations of KNO3 (100, 75 and 50%), longest incubation time (6 days) and slowest drying were most effective in reducing the mean germination time and increasing the mean germination rate at the two temperatures studied.