Seed and Embryo Germination in Ardisia crenata

Ardisia crenata is an evergreen shrub with attractive bright red berries. Although this species is usually propagated by seed, the seeds take a long time to germinate with conventional sowing methods. We investigated the germination capacity of seeds and embryos collected in different months and the effects of seed storage conditions, germination temperature, water permeability of the seed coat, and the endosperm on seed germination. Seeds and embryos collected in late September or later showed good germination rates. Seeds germinated more rapidly after longer periods of storage at low temperature (approximately 5°C), and those stored in dry conditions showed lower emergence frequency than those stored in wet conditions. Seeds germinated at 15–30°C, but not at 5–10°C. Removal of the seed coat enhanced water uptake and seed germination. Seeds with various proportions of the removed seed coat were sown on a medium supplemented with sucrose. The germination frequency increased as the size of the remaining endosperm decreased. However, the opposite results were obtained when seeds were sown on a medium without sucrose. We concluded that the optimal temperature of 25°C is the most critical factor for seed germination in A. crenata. 1. Introduction The genus Ardisia (Myrsinaceae) contains approximately 400–500 species of evergreen shrubs, which are distributed in the subtropical and tropical regions around the world [1]. Several Ardisia species have been used for medicinal purposes, because they contain a wide array of biologically active phytochemical constituents such as bergenin and ardisin [2]. Ardisia crenata is one of the most widely grown species in the genus and is distributed throughout East Asia, including Japan. It grows to approximately 1？m high and has glossy, dark green leaves, and attractive bright red berries. It is grown as an ornamental plant in gardens and as a houseplant. Although vegetative propagation methods such as cuttings are sometimes used to propagate A. crenata plants [3], the use of seeds has advantages for mass propagation. However, it can take more than 13 weeks to achieve 80% of seed germination [3]. This long period for seed germination hinders and delays the breeding of this shrub. Seed germination is controlled by several environmental factors, such as seed moisture content, temperature, and light. Seed condition also affects germination; for example, the seed coat may be water impermeable, or the mature seed may contain an underdeveloped embryo that only grows to full size after imbibition [4, 5]. In Japan, fully ripened