GROWTH AND GERMINATION CHARACTERISTICS OF THREE AKEBIA LIANA SPECIES FOR REVEGETATION

Abstract

Three woody climbing species of Akebia (Lardizabalaceae), A. quinata (AQ), A. × pentaphylla (AP) and A. trifoliata (AT), have been used for revegetation applications. However, the optimal applications of each species have not been established, as their seed germination and growth characteristics are poorly known. In the present study, we clarified their seed germination and stem growth characteristics to evaluate their potential for use as revegetation materials. Seed germination was conducted under continuous light (24 hours) with alternating temperature conditions (28 ºC/ 15 ºC, each for 12 hours) using five different pretreatments on seeds harvested in 2023. In assessments of stem growth, the number of climbing and creeping individuals, and the basal diameters of each were surveyed in 17 habitats in Nagano Prefecture, Central Japan, in 2023. In all pretreatments, the germination percentage was high in AP (maximum: 73%), but poor in AQ and AT (maximum: 5% and 10%, respectively). The development of cotyledons after germination was also faster in AP than in AQ or AT. The ratio of climbing individuals was significantly lower in AP (0.34) than in AQ and AT (0.67 each), and the basal diameter was significantly larger in climbing individuals than creeping individuals in all species. Consequently, it is considered AP is better suited for rapidly covering the ground surface by direct seeding, whereas AQ and AP would be better suited for climbing along pergolas and forming hedges by planting seedlings.