Biomass, carbohydrate, and leakage conductance in buds of six ornamental tree species subjected to a “false spring” in Northeast China

Information is highly scarce about the possible effect of a late spring frost on physiological response of buds in ornamental trees. In this study, spring temperature of Changchun at Northeast China was recorded to identify the characteristics of a false spring by detecting extraordinary warming and sudden freeze in early April of 2017. Buds of six local ornamental tree species were investigated for their dynamics in biomass, non-structural carbohydrates, frost resistance on days of 7, 14, 21, and 28 April 2017. According to a comparison with spring temperature records historically from 2007 to 2016, a false spring was determined. Black pine (Pinus tabuliformis var. mukdensis) had greater bud biomass than apricot (Prunus sibirica L.). Peach (Prunus persica L. var. persica f. rubro-plena Schneid.) reserved greater non-structural carbohydrate content in post-chilling buds than black pine, and apricot and willow (Salix babylonica L.) had greater soluble sugars and starch contents in buds, respectively. Cumulative number of days with temperature below 12°C had a negative relationship with relative conductance in sorbus (Sorbus pohuashanensis [Hance] Hedl.). Chokecherry (Padus virginiana ‘Canada Red’) had greatest bud starch content on 21 April. Overall, a late spring frost imposed interruption on carbohydrate metabolism rather than direct damage on buds of ornamental trees before late April. Advanced warming induced more pronounced negative impact of a false spring than the sudden decline of minimum temperature.