Stenocereus beneckei seed mass variation and its relationship to germination

Seed size variation plays an important role in germination and seedling establishment. Stenocereus benekei seed germination of five mass classes in four sowing dates was studied with the aim to gain insight in species strategies within the first phases of its life cycle. S. benekei has the largest (3.2 +/- 0.4 mm length, 2.6 +/- 0.3 mm breadth) and heaviest (11.8 +/- 2.7mg) seeds of the Stenocereus genus. Number of seeds per fruit varied from 25 to 200, showing a positive correlation between fruit size and number of seeds. Seed germination percentage was higher than 75% in four categories under laboratory conditions. The lower germination percentage (11%) was found in the smallest seeds and the highest in medium size seeds (84%). Germination curves showed statistical differences among the five seed mass categories and dates, as well as among seeds of the same mass category germinated in different dates. Germination curves revealed that in the medium and large seeds (3-5) germinability was higher shortly after harvesting, but an inverse behaviour was observed in the smaller seeds (categories 1-2). The results suggest that seeds of S. beneckei respond differentially depending upon their physiological maturity and the date after sowing.