A Thermogradient Bar Apparatus for the Study of the Germination Requirements of Buried Seeds in Situ

Summary An apparatus is described which enables a layer of soil, containing naturally‐buried seeds, to be subjected to controlled temperature fluctuations over the range 5 to 30 °C, in the presence or absence of light. Results obtained from the use of this apparatus are presented for 14 species, all common constituents of the buried seed bank and nearly all weeds of arable land or pasture. At least partial inhibition of germination by darkness was found in all 14 species and stimulation of germination by temperature fluctuations in all but one. In some cases germination was inhibited by very large fluctuations. There was some evidence that a requirement for temperature fluctuations may be induced by burial. The ecological significance of the results and the limitations of the thermogradient apparatus are discussed and some further applications of the apparatus are suggested.