Embryo development in seeds of Ilex paraguariensis A.St.-Hil. in stratification treatments

The specie Ilex paraguariensis A.St.-Hil., known as yerba mate, is propagated by seeds that have morphophysiological dormancy. This study aimed to answer the following questions: (1) What are the changes that occur in the Ilex paraguariensis embryos during moist stratification? and (2) May the incorporation of chemical fertilizers in moist stratification medium promote an increase in the germination percentage in yerba mate seeds? For this purpose, yerba mate seeds were subjected to two stratification treatments: between two layers of moist sand and between two layers of moist sand with mineral fertilizer plus a control, for 180 days. At intervals of 30 days, seeds were removed for structural anatomical analysis and, at 150 and 180 days, also for germination tests at 25 °C, which were monitored for 180 days. The treatment with the highest germination percentage during stratification (15.4%) and in the germination tests (15.2 and 20.1%) was the one with mineral fertilizer incorporated in the moist stratification medium. Only in this treatment the embryos in more advanced stages of development (torpedo and mature). It is concluded that embryo development and germination were favored by moist stratification medium with the addition of chemical fertilizers.