Effects of dormancy-relieving chemicals on seeds in soil.
Field studies were carried out during 1989-90 in the UK to investigate the effects of mixtures of ammonium nitrate (as Nitram), thiourea, ethephon (as Cherone), sodium azide and calcium peroxide, weekly cultivation, and cultivation at 7 times during one year on the depletion of soil seed banks. Where Chenopodium album and Solanum nigrum represented 80-90% of the natural seed bank, the natural annual rate of seed depletion approached 90%. Seedling emergence was higher in some treatments, but did not affect seed depletion. Soil pH affected the impact of sodium azide; it damaged and often killed seeds of C. album and Avena fatua at pH 4, while it increased A. fatua germination at pH 6.4. The response to potassium nitrate with ethephon was unaffected by soil pH.