Ma. Thornton et al., The promotive effect of combustion products from plant vegetation on the release of seeds from dormancy, PLANT GR R, 28(2), 1999, pp. 129-132
In darkness, dormancy was imposed on seeds of lettuce (Lactuca sativa L. cv
. Grand rapids) by high temperature and on seeds of oilseed rape (Brassica
napus L. cv. Apex) by osmotic stress using polyethylene glycol (PEG 8000).
In both cases, dormancy was broken by incubating the seeds in aqueous extra
cts of combustion products from Salix viminalis wood chips or Themeda trian
dra leaves. Dormancy of rapeseed, but not lettuce, was also broken by a sol
ution of smoke from burnt straw of Triticum aestivum. The greatest stimulat
ion from burnt vegetation was achieved with an aqueous extract of pyrolysed
willow wood chips, which had been subjected to temperatures of up to 800 d
egrees C during combustion in a down-draught gasifier. This suggests that s
ome biologically active substances obtained from combustion of plant tissue
s are highly heat-stable.