A Method for Measuring the Effects of Soil Salinity on Seed Germination with Observations on Several Crop Plants1

THERE is considerable evidence that many crop plants are particularly sensitive to soil salinity during germination and seedling growth. Crops growing on soils subject to salinization are frequently interspersed with numerous barren areas. That is, there may be a sharp demarcation between fair growth of plants and no plants at all. These barren spots often delimit the areas where soil salinity was sufficiently high at planting time to prevent seed germination. It is especially important, therefore, that the level of salinity in the soil be below the limit of tolerance of a crop during the time of germination and seedling growth. Information on the salt tolerance of various crops during this phase of growth is very meager even though it may be a primary consideration in production on saline soil. Uhvits has recently reviewed the literature on this subject in connection with her studies on the effect of osmotic pressure of the substrate moisture on water absorption and germination of alfalfa seeds. It is difficult, if not impossible, to evaluate adequately the level of salinity conditioning the germination of ' seeds under field conditions. The amount of soil moisture and the salt concentrations adjacent to the seed are continually changing through the influence of evaporation, capillary transmission, rainfall, or irrigation. Although information is needed as to the effect of the variations in soil moisture and salt content upon germination, it is first necessary to ascertain the effect of varying levels of salinity on germination when all other factors are held constant or as uniform as possible. A technic is being used at this Laboratory which appears to evaluate satisfactorily the influence of a given level of soil salinity on seed germination with a minimum of complication by other variables.