Abstract

GILLIJ, Yanina G.; GALUSSI, Alberto A.  and  PERISSE, Patricia. Morphoanatomical and chemical characteristics of Desmodium incanum (Fabaceae, Desmodieae) seed coat and its association with dormancy. Lilloa [online]. 2023, vol.60, n.2, pp.241-257. ISSN 0075-9481.  http://dx.doi.org/doi.org/10.30550/j.lil/1852.

Desmodium incanum (Sw.) DC, is a species of good forage quality characterized by the presence of seeds with different levels of physical dormancy. The aim of this work was to investigate the morphological, anatomical and chemical characteristics of the seminal integuments associated with the levels of physical dormancy. We analyzed seminal integuments that presented different levels of dormancy, classifying them from highest to lowest speed of hydration in degrees of permeability 1, 2 and 3. The seeds were harvested between 2017 and 2020 in areas located in the province of Entre Ríos (Argentina). Scanning and transmission electron microscopy techniques were used to morphoanatomical analyses of seed integuments. The chemical components were determined using to Van Soest methods to calculate the percentages of cellulose, hemicellulose, lignin and cutin of the cell wall and cell contents. The determination of total polyphenols was carried out using the Folin-Denis technique whereas the vanillin method was used for condensed tannins. The results show that the semi- nal integuments with greater impermeability to water presented differences in the ornamentation pattern, palisade macrosclereids with greater cellular compactness, changes in the arrangement in the lens zone and greater thickness of the cell wall. The osteosclereids presented similar lengths and widths. Differences were detected in the amounts of tannins (1.6 and 2.3%), pectic substances (9.7 and 15.1%), cellulose (30.9 and 53.5%) hemicelluloses (46.2 and 23.5%) and lignin (0.4 y 0.5 %) for grade 1 and grade 2 and 3 samples respectively. This study showed differences in both the morphoanatomical features and the proportions of the chemical components within the seminal integument as a function of the level of water permeability, aspects that are associated with depth of physical dormancy.

Keywords : Lignin; macrosclereids; permeability; seeds; tanins..

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