Morfoanatomía, histoquímica y germinación de las semillas de Mammillaria parkinsonii Ehrenb. (CACTACEAE)

A BSTRACT : Mammillaria parkinsonii is a mexican endemic species protected by NOM-059-SEMARNAT-2010 in the special category (Pr), thus the present study is a contribution to the knowledge of the morpho-anatomy, histochemistry and germination of Mammillaria parkinsonii seeds from a population in Tolimán, Querétaro which is characterized by a high diversity of cacti. The anatomical and histochemical descriptions were made on 20 randomly selected seeds, which were processed using standard protocols for scanning electron and light microscopy studies and to obtain permanent and semi-permanent slides. For germination study 210 seeds were sown in Petri dishes on agar, using six replicas; weight and size were obtained using 50 seeds randomly selected. The results show that the seed coat is formed by a non-striated cuticle with pectics and proteinaceous substances. The exotesta occupies 6.8% of the total volume of the seed, it has lignified-suberized and protein-containing anticline walls, forming U-type undulations with protrusions. The endotegmen is suberized and an embryonic membrane lacking ergastic contents surrounds the embryo. The endosperm is confined to a dorsal ridge. The embryo is globose, with two cotyledonous protrusions, and the hypocotyl assumes the reserve function with a "globoid crystals/protein bodies" association. The micropylar hilum region is small and oval, filled with parenchyma. Germination started on day 5th and ended on day 29 th , with a mean germination time on day 8.9. The final germination percentage was 74.29%. The age, seed size, crystal and protein reserve as well as germination percentage of the M. parkinsonii suggest a potential orthodox or intermediate behavior to form soil seed banks in a desert habitat.