<b>Tratamientos pregerminativos y morfología <i>in vitro</i> de plántulas de <i>Echinocactus platyacanthus</i> y <i>Echinocactus horizonthalonius</i></b><b><i></i></b>

Echinocactus platyacanthus and Echinocactus horizonthalonius are in constant risk due to the deterioration of its natural habitat. The objective was to compare seed weight among E. platyacanthus and E. horizonthalonius and what effect does it have with seeds´s morphometric variables. To determine if the interaction among pregerminative treatments and seed weight have an effect on the germination percentage and seedling size as well and produce a morphological description of the seedlings for 60 days. The seeds of E. platyacanthus and E. horizonthalonius were divided into three weight categories. The pregerminative treatments were control, soaking in water for 24 hours, 25% sulfuric acid, 30% hydrochloric acid and mechanical scarification. The seedlings obtained with mechanical scarification were photographed for morphological description for 60 days. Weight category 3 of E. horizonthalonius seeds showed the largest size with 3.06 ± 0.07 mm in length, 2.28 ± 0.07 mm in width, and an area of ​​5.09 ± 0.20 mm2. E. platyacanthus seeds of weight category 2 with 24-hour soaking water treatment, H2SO4, and mechanical scarification obtained 100% germination. The interaction of pregerminative treatments and seed weight indicate that the highest percentage of germination and seedling size is obtained with medium-sized seeds of E. platyacanthus and E. horizonthalonius. The mechanical scarification treatment promotes the hightest germination in E. horizonthalonius seeds. The seedlings of both species presented morphological differences in the first 60 days of growth.