The effects of pre-sowing seed treatments on the germination and emergence of lettuce seeds at high salt concentrations

Abstract

Radicle emergence in lettuce seeds cultivar ‘Hilde’ was reduced by NH 4NO 3 above 8×10 −2M, while radicle extension was inhibited by 8×10 −2M NH 4NO 3 and no seedlings emerged. Inhibition of radicle emergence by 8 and 16×10 −2M NH 4NO 3 was prevented by soaking seeds for 4 h before sowing in a mixture of GA 4 7 and kinetin+phosphate buffer, and was partially prevented by soaking them for 4 h before sowing in phosphate buffer. These treatments did not prevent inhibition of radicle emergence by 32×10 −2M NH 4NO 3, but seeds soaked in growth regulators or phosphate buffer before sowing and taken from this NH 4NO 3 solution after 7 days and washed to remove excess salt gave 45–52% germination compared with 12 % for untreated seeds. Pre-treatment of the seeds did not prevent the inhibitory effect of NH 4NO 3 on radicle extension. In field experiments seeds treated with growth regulators + phosphate buffer or phosphate buffer alone gave a higher final percentage emergence from soils given 125 kg N/ha than did untreated seeds.