Anatomical and chemical characteristics of the seed coat of Medicago sativa L. (alfalfa) cv. Baralfa 85 seeds and their association with seed dormancy

AA Galussi, JA Argüello, MM Cerana, M Maximino, ME Moya

Abstract


Seeds of alfalfa (Medicago sativa L.) can exhibit seed coat imposed dormancy, which produces hard seeds within a seed lot. These seeds do not germinate because they do not imbibe water dueto a barrier to water entry in the seed coat. The aim of this work was to analyze the anatomical and chemical characteristics of the testa of alfalfa seeds with respect to water permeability levels. The anatomy of seeds of the cv. Baralfa 85 was studied and structural substances, polyphenols, tannins and cutin present in the testa of seeds of different water permeability levels were determined. The anatomical characteristics of the seed coat and the proportions of components were found to determine the permeability level of the seed coat, an aspect that is associated with the physical seed dormancy level. Anatomically, increased thickness of the testa was associated with a lower permeability level. The difference may be attributed to the variationin cuticle thickness, length of macrosclereids and thickness of the cell wall, and presence and development of osteosclereids. From the physiological and chemical points of view, the mechanism of physical dormancy of the testa is explained by a greater amount of components that repel water and cement the cell wall, such as polyphenols, lignins, condensed tannins, pectic substances, and a lower proportion of cellulose and hemicellulose.

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Los trabajos publicados en esta revista están bajo la licencia Creative Commons Atribución-NoComercial 2.5 Argentina.

Phyton. International Journal of Experimental Botany. ISSN print 0031-9457 ISSN en line 1851-5657 Fundación Rómulo Raggio Gaspar Campos 861,  Vicente López, Buenos Aires, Argentina (C.P. 1638) Tel 54 11 4791-0868 / 4796-1456 revistaphyton@fund-romuloraggio.org.ar www.revistaphyton.fund-romuloraggio.org.ar