Changes in desiccation tolerance and respiratory rates of immature Caesalpinia echinata Lam. seeds by PEG treatment

Ana Clara Ferreira Baptista Araujo, Claudio Jose Barbedo

Abstract


Seed storage is an important tool for the ex situ conservation. Orthodox seeds can be stored for long periods, but recalcitrant ones have difficulty in their long term storage. There is a wide variation in the degree of desiccation tolerance between orthodox and recalcitrant seeds, leading authors to consider the existence of recalcitrance levels and, recently, that the variations are due to the maturation stage at shedding. Thus, the recalcitrant behavior would result from a premature shedding. In this work we analysed physiological relationships at different stages of development in immature Caesalpinia echinata orthodox seeds, comparing them to those described for recalcitrant seeds in order to verify their proximity of behavior. Therefore, we analysed desiccation tolerance of seeds collected at diferent ages, with or without PEG treatment, at different levels of drying (40%, 30%, 20% and 10% water content, wet basis). Changes in water potential, germination, vigor and respiratory rates of the seeds were analyzed and the results showed that: 1) desiccation tolerance increased with the evolution of the maturation; 2) PEG treatment did not improved desiccation tolerance; 3) PEG treatment decreased the oxidation of seeds which is considered the most important factor on C. echinata seed deterioration on storage.

Keywords


tolerance to desiccation; osmopriming; maturation

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