Redução da sensibilidade à dessecação e ao armazenamento de sementes de espécies florestais

Abstract

The impossibility of storing unorthodox seeds prevents ex situ conservation of these species and makes it difficult to use them in environmental restoration programs. Understanding the mechanisms that allow the desiccation and the storage is fundamental for new strategies to increase water loss capacity and the longevity of recalcitrant and intermediate seeds during storage. Several studies have obtained success with the use of osmotic agents such as PEG and ABA application in the reinduction of desiccation tolerance in germinated seeds of orthodox species, allowing for a better understanding of the mechanisms associated with desiccation tolerance. Therefore, it was sought with the use of PEG and ABA the reduction of the sensitivity to the desiccation and storage of Genipa americana and Magnolia ovata seeds. The seeds were submitted to different PEG and/or ABA solutions, after that dried, and stored. Analysis of germination percentages, normal seedlings, IVG, and electrophoretic profile of total proteins, resistant to heat and enzymes catalase, peroxidase and superoxide dismutase were performed. In the M. ovata seeds, PEG negatively influenced the germination and formation of normal seedlings, whereas ABA seems to play an important role in the desiccation tolerance of this species, since it allowed for greater seed germination after drying. In G. americana seeds, some treatments with PEG and/or ABA were efficient for germination maintenance after the drying and storage. No significant changes in the electrophoretic patterns of enzymes and proteins were observed. However, the use of PEG and ABA may have induced protein synthesis and activated other mechanisms related to the desiccation tolerance and storage in Genipa americana and Magnolia ovata seeds.