Influence of exogenous hormones on seed germination and seedlings growth of fast-growing Ochromalagopus postprint

Abstract: Balsa wood (Ochroma lagopus Swartz) is characterized by its fast growth, short life cycle, minimum wood density and uniform material texture, and widely used in the wind power industry and the aviation industry. However, challenges such as low natural seed germination rates due to hard seed coat and prolonged seed dormancy, as well as high seedling variability restrictedseverely standardized breeding and large-scale cultivation. In order to improve the seeds germination, seedlings homogeneity and growth, this study performed dish germination and pot control experiments to evaluate the effects of varying concentrations of indoleacetic acid (IAA), benayl aminopurine (6-BA), and gibberellin (GA) on seed germination and seedling growth for balsa. The results indicated that (1) GA promoted seed germination and embryo growth, while IAA and 6-BA inhibited seed germination, the biomass and length of embryo bud and embryo root (P<0.05), and the inhibitory effect increased with the increasing of concentration. (2) On the contrary, GA, IAA and 6-BA boosted the growth of seedlings, and the promoting effect on grounddiameter was greater than that on the height and root length, and the effect enhanced with the increasing concentration (P<0.05). (3) In addition, GA and IAA also significantly increased the underground biomass and root-crown ratio of seedlings (P<0.01). This study concluded that GAenhanced seed germination by breaking seed dormancy, while GA, IAA and 6-BAnot onlyfacilitated the performance of seedlings but also increase the root-crown ratio, ultimatelyaccelerating their water absorption capacity and drought resistance. These findings provideda theoretical basis and practical significance for the seedling raising technology and cultivationmanagement of balsa wood.