Effects of desiccation on Euterpe edulis Martius seeds

V虲Tor Panza,Horacio L Maroder,Sara Maldonado,Ver覰Ica L罥Nez

doi:10.32604/biocell.2007.31.383

Abstract

Information on desiccation sensitivity of Euterpe edulis seeds under two drying rates is presented. The sensitivity was studied during the course of germination and normal germination. The water content was evaluated for both seeds and embryos. Results showed the following: (a) For both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) For both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) Under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) Critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. Critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. From the beginning of both drying treatments, changes in nuclei and vacuoles were observed, but, when seed water content was reduced to below critical values, the cells became severely plasmolyzed, the vacuoles highly distorted, and the nuclei formed an almost homogeneous mass with the chromatin and the nucleoplasm, which suggests irreversible DNA damages. BIOCELL 2007, 31(3): 383-390 ISSN 0327 9545 PRINTED IN ARGENTINA

Highlights

Euterpe edulis exhibits recalcitrant seed-storage behaviour; in other words, seed viability begins to decrease at approximately 39% seed water content and is definitively lost at 21% water content (Andrade, 2001; Martins et al, 2000; Reis et al, 1999)
Berjak et al (1989) describe the difficulty of comparing water contents when embryo or whole seed are measured. We found that such difficulty was exacerbated in this species because the embryo constitutes only 0.54% of the seed fresh weight
We observed that the development of a seedling with three leaves did not always follow button protrusion, and some death could occur after plumule emergence

Summary

Introduction

Euterpe edulis exhibits recalcitrant seed-storage behaviour; in other words, seed viability begins to decrease at approximately 39% seed water content and is definitively lost at 21% water content (Andrade, 2001; Martins et al, 2000; Reis et al, 1999). Panza et al (2004) report subcellular recalcitrant features of the E. edulis embryo tissues, i.e., cells highly vacuolated (at high water content), almost lacking storage reserves, with abundant endomembranes, and abundant ergastic substances. The differential water content between the embryo axis (and embryo) and the storage tissue presents a difficulty for interpreting the experimental results on recalcitrant seeds (Berjak et al, 1989). This difficulty is exacerbated when the embryonic axis constitutes a small fraction of the total volume of the seed, and its water content is considerably higher than that of the storage tissues (ISTA, 1989), which is the situation with E. edulis seeds. There are conflicting opinions on this subject (Bonner, 1996; Finch-Savage, 1992; Pritchard et al, 1995)

Methods

Results

Conclusion