Breaking seed dormancy in specially protected Turbinicarpus lophophoroides and Turbinicarpus pseudopectinatus (Cactaceae)

Turbinicarpus lophophoroides (Werderm) and Turbinicarpus pseudopectinatus (Backeb) are cacti species under special protection status. Both species have seed dormancy. To help preserve these species we ran seed germination experiments to determine the effect of seed age and putrescine on breaking seed dormancy. The treatments used were seed age (from four different years) and the administration of exogenous putrescine (0.1 mu mol/L, 0.1 mmol/L and a control). The seed collection years were 2001, 2002, 2004 and 2005 for T. lophophoroides, and 2002, 2003, 2004 and 2005 for T. pseudopectinatus. The response variable evaluated was the final germination percentage. Turbinicarpus lophophoroides showed the greatest germination percentage for seeds that had been collected for 4 years (2001), both in the control (66%) and in the 0.1 mu mol/L putrescine (54%) treatments. Seeds of T. pseudopectinatus with the greatest germination percentage (48%) were those collected within a year (2004) for the control group. This implies that putrescine inhibited the germination of T. pseudopectinatus. The results show that both species have the potential to produce seed banks.