Germination of the hard seed coated Opuntia tomentosa SD, a cacti from the Mexico valley

Germination of Opuntia tomentosa seeds collected during 1998 was evaluated using treatments of scarification (H2SO4), gibberellic acid (GA(3)) dry heat, soaking, light, after-ripening and stratification at constant and alternating temperatures. Seeds were positive photoblastic, germinated best at constant temperatures, and showed a combined dormancy (physiological and physical). Acid scarification, GA(3), and heating induced germination, soaking and stratification did not. After 15 and 18 months, GA(3) inhibited germination. Dormancy of seeds collected during 2000 was overcome with a short scarification. Differences between baths could be due to 1998 was very dry due to "El Nino". It is important to identify maternal effects. (C) 2003 Elsevier Science Ltd. All rights reserved.