Anatomical and physicochemical characterization of the Araucaria angustifolia seed coat

Abstract

Seed coat plays an important role in the embryo protection and seed germination. This study aimed to characterize the anatomical structure, histochemical and physicochemical aspects of the seed coat of Araucaria angustifolia Kuntze. Light and scanning microscopy usual procedures, and histochemical tests were used to describe and characterize seed layers, as well as to determine their extractive contents. Functional groups of the integument coat layers were observed by Fourier transformed infrared spectroscopy. Color analyses were performed in CIE 1976 L*a*b* color space. Wettability of the layers was evaluated by contact angle analysis. The anatomical and chemical features observed in the seed layers include the rucose cuticle and the presence of many layers of sclerenchyma in the mesotesta; and the chromaticity due to extractive content and phenolic compounds in the endotesta. The wettability varied among layers according to their structure. These features information contribute to a better understanding on the services provided by the Araucaria angustifolia seed coat.