Seed dormancy and germination of the three tropical medicinal species Gomphandra luzoniensis (Stemonuraceae), Nothapodytes nimmoniana (Icacinaceae) and Goniothalamus amuyon (Annonaceae)

The three tropical species Gomphandra luzoniensis, Nothapodytes nimmoniana and Goniothalamus amuyon contain important cancer-fighting drugs; however, little is known about how to propagate these species from seeds. Thus, the aim of this study was to determine the germination requirements of seeds of each of these three species in order to provide an effective protocol to produce plants. Fresh seeds of G. luzoniensis germinated up to 73% at high temperatures in light in 4 weeks, and embryos were underdeveloped. Most seeds had morphological dormancy (MD), but a proportion of them had morphophysiological dormancy (MPD). Fresh seeds of N. nimmoniana germinated up to 50% in light in 4 weeks, embryo length increased by 17% before radicle emergence and ≥ 89% of the seeds had germinated after incubation for 6 weeks in light at high temperatures. Thus, about 50% of the seeds have MD and about 50% MPD. Fresh seeds of G. amuyon incubated at 30°C in light for 4 weeks germinated to 69%, whereas at the other incubation temperatures germination took longer than 4 weeks. Embryo length increased 213% before radicle emergence, and after 8 weeks of incubation at high temperatures ≥ 80% of the seeds had germinated. As in the other two species, the seed population consisted of a mixture of MD and MPD. Incubation of seeds of these three species at high temperatures (e.g. 25, 30 and 30/20°C) for up to 2 months is recommended for germination and thus seedling production.