Effect of seed desiccation and sucrose concentration on the in vitro establishment of mangabeira (Hancornia speciosa Gomes var. gardneri) seedlings

摘要

Mangabeira (Hancornia speciosa Gomes var. gardneri) is one of the most important fruit trees in the cerrado biome, its fruits being highly valued both for in natura consumption and for processing. Although its seeds are delicate, losing viability within a few hours after collection, seeds still represent the predominant tool of propagation multiplication of this species, since the plant encounters limitations in the formation of adventitious roots, hindering vegetative propagation. Thus, the present work aims to evaluate the in vitro establishment of Mangabeira seedlings as a function of the extent of natural desiccation and the sucrose concentration in the culture medium. Four sucrose concentrations (15, 30, 45 and 60 g L-1) and four natural drying periods (24, 48, 96 and 192 h after the seed pulping) were used in a factorial experiment. 60 days after in vitro culturing of the naked embryos, the following variables were evaluated: germination %, germination speed index (GSI), mean germination time (MGT), oxidation index, culture medium contamination index, length of the largest root, stem diameter, seedling height and number of live and dead leaves. The interaction between desiccation times and sucrose concentrations was not significant for any of the variables analyzed. Germination was influenced only by the desiccation time, being reduced after 106 hours of natural drying. Increasing concentrations of sucrose up to 60 g L-1 reduced GSI and seedling height. In contrast, leaf mortality decreased, which contributed to the production of seedlings with greater ability of acclimatization to field conditions.