Robustness of germination analysis methods for Copaifera langsdorffii Desf. (Fabaceae) seeds

Abstract

Germination of Copaifera langsdorffii Desf. seeds is non-uniform and asynchronous and there is still no consensus on the factors affecting it. Thus, the goal was to measure the robustness of pre-germination methods used to determine germination rates of C. langsdorffii seeds of different levels of quality and to present criteria for seedling classification that culminate in the officialization of one of these methods. Pre-germination methods were tested and the scarification of seeds sterilized with 0.05% NaClO was the most efficient for maximizing germination potential. Seeds of different quality were then treated with this method and collaborative tests evaluated by Ministry of Agriculture laboratories. These evaluations were based on normal seedlings produced from each seed lot. Morphofunctional classification was used throughout to determine essential seedling structures. Robustness of the method was measured by variance and the coefficient of variation of repeatability and reproducibility. Scarification and sterilization with sodium hypochlorite made it possible to both estimate the germination potential of seeds of different quality levels and reduce seedling infection and seed mortality. To analyze germination based on seedling criteria, normal seedlings of this species were defined as having thick cotyledons that are detached from the seed coat, developed hypocotyls and epicotyls and primary roots. These seedlings have woody primary roots and thick, sometimes poorly developed hypocotyls. Even though C. langsdorffii is a forest species and subject to high variability, the proximity of the percentages of normal seedlings among repetitions (low repeatability) and low inter-laboratory reproducibility reflecting the uniformity generated by the method.