Germinação e vigor de sementes de melancia com diferentes ploidias submetidas a tratamentos pré-germinativos

Abstract

Triploid and tetraploid watermelon seeds have low germination and, as such, need seed treatments to alleviate this problem. Techniques to improve seed germination are important factors to increase seed potential and stand uniformity in the field. The objective of this study was to evaluate the effects of pre-germinative treatments in diploid, triploid and tetraploid watermelon seeds. The seeds were subjected to the treatments: control, maceration, mechanical scarification, gibberellic acid (GA3) and mechanical scarification + GA3. After the treatments, the seeds were sown in rolls of germination paper imbibed in distilled water in a 2:5 proportion (w:v), and germinated at 25°C in germination chambers. Germination percentage and seedling growth were evaluated after 5 and 12 days. Seedling emergence was evaluated in a 50% shaded green house in trays filled with soil. The daily counting of seedling emergence were carried out until emergence stabilization, to determine the emergence percentage and emergence speed index. Although the pre-germinative treatments did not improve germination and emergence of all the seeds evaluated, it was observed that gibberellic acid and scarification, separately and associated, promoted high seedling growth derived from diploid and tetraploid seeds and also maceration improved tetraploid seedling growth.