Temperature during soybean seed storage and the amount of electrolytes of soaked seeds solution

Abstract

The electrical conductivity test measures the electrolytes that leach out of seeds when they are immersed in water and this leakage is an indication of seed vigor. The level of standardization reached by the procedures of this test is such that the test is recommended for pea seeds and suggested for other large seeded legumes, including soybean [Glycine max (L.) Merrill]. This study was conducted to contribute to the standardization of this test for soybean seeds by verifying whether the seed storage temperature influences the composition of the leachate from soaked seeds solution. Two soybean seed lots of distinct physiological potential were stored in moisture-proof containers either at constant temperatures of 10ºC and 20ºC or at the temperature of 20ºC during the first seven months of storage followed by a change to 10ºC for the rest of the storage time (nine months). The chemical composition of the soaked water was evaluated every three months from January to October 1998. The highest amount of leakage was observed for potassium, followed by calcium and magnesium, iron and sodium regardless of temperature and storage period. The amount of electrolytes in the soaked water increased as the period of time and the temperature of storage increased. On the other hand the amount of leakage decrease along the time for those seeds stored at 10ºC or transferred from the temperature of 20 to that of 10ºC. The temperature at which soybean seeds remain during storage may affect the amount of electrolytes in the soaked water and consequently the results of the electrical conductivity test.