Micromorphological observation of seed of Eucalyptus species and multivariate statistical analyses and modeling of their germination under salt stress and osmotic constraint seed of Eucalyptus species

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Mechergui Kaouther


Abstract : Micromorphological characters include surface, lenght and widh of seeds were recorded for 19 species of Eucalyptus (Myrtaceae) using stereomicroscope to determine the importance of seed morphological characters as an additional tool for identification. With the aim of selecting and valorizing abiotic-stress-tolerant species with landscape and industrial values and would be a potential solution for valorizing dry arid area and development of land degradation, we launched the assessment of the performance of five Eucalyptus species (E. torquata, E. sargenti, E. gillii, E. gompho-cornuta  and E. microtheca) under salinity and osmotic potentiel constraints. Several NaCl concentrations (0, 3, 6, 9, 12, and 15 g L-1) and several osmotic potentiel (0, -0.03, -0.1, -0.7, -1 and -1.6 MPa) were applied to seeds cultivated in petri dishes for a period of one month. Germination rates, means time of germination and coefficent of velocity were evaluated to better understand the salt stress and osmotic potentiel effect on germination. Univariate and multivariate analyses were used to identify the major characteristics pertaining to salinity tolerance. Modeling of germination under both constraints saline and osmotic stress is carried out to predict the behavior of the species. The hybrid E.gompho-cornuta was more tolerant to salt stress (15 % at 12 g L-1) and osmotic potential (61 % at -1.6 MPa) than the others species of Eucalyptus; it showed a higher germination percentage under all tested potentials, when compared to the not hybrid species of Eucalyptus. Our analyses of seeds morphology revealed that the observations shown diversity of morphological characters in seeds. Area, lengh and widh of seeds vary significantly between species of Eucalyptus. Micromorphological characters can provide basis for classification and delimitation of genus Eucalyptus.

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