Chitosan oligosaccharide addition affects current-year shoot of post-transplant Buddhist pine (Podocarpus macrophyllus) seedlings under contrasting photoperiods

Abstract

Abstract: Chitosan oligosaccharides (COS) have been used as modifiers to promote growth and mineral nutrient utilization in crop plants, but its over-year effect on current-year shoot (CYS) of juvenile trees is still unclear. In this study, Buddhist pine (Podocarpus macrophyllus) seedlings were cultured under natural and extended photoperiods with or without COS addition for one year. In the following spring, parameters of leaf length, biomass accumulation, and N content in CYS were found to be increased by COS addition under the extended photoperiod. P concentration of COS-treated seedlings was lower under longer photoperiod, but both N and P concentrations were negatively correlated with leaf length and biomass accumulation, suggesting the utilization of N and P for growth demand of CYS. The sole addition of COS mainly resulted in whole-plant P accumulation. However, when combined with the extended photoperiod, COS addition showed over-year effect on biomass accumulation and N content in CYS of transplanted Buddhist pine seedlings. Further studies are needed to confirm these results on other tree species.