Resistance to Water Absorption in Germinating Rapeseed (Brassica napusL.)

Dynamics of the imbibition phase of rapeseed (Brassica napus L.) was studied by evaluating water content-water potential relations and the permeability to water. It was found that resistance to water absorption was very high (diffusivity was very low) during the early stages of water absorption. As seed water content increased, resistance decreased by more than six orders of magnitude. The concept of hydraulic conductivity of a seed was introduced. The change in hydraulic conductivity with change in seed water content was similar to that observed for diffusivity. It was shown that at late stages of water absorption hydraulic conductivity approached values found in soils at the dry end of the available water range. For this reason it was suggested that hydraulic conductivity in soil may have an influence on imbibition rate in the late stages of water absorption.