Fig.1

Photoperiodic pathway (A), field phenotypes (B) and tiered deployment strategy (C) in poplar A: Schematic diagram of the molecular pathway underlying short-day-induced growth cessation and dormancy establishment. B: Phenotypic summary of PtFT2OE and PtELF3KO lines over five growing seasons at the Wuhan field station, including mean annual increment in diameter at breast height and mean annual carbon storage increment per plant. Error bars represent standard deviation of biological replicates; n=8?9. C: Schematic diagram of the climate-zone-based tiered implementation strategy. Numbers represent the temperature."

Fig.S1

Overexpression of PtFT2 attenuates SD-induced growth cessation and bud set in hybrid poplar a: Schedule diagram of tFT2 over-expression (PtFT2OE) vector construction. b: Positive test and relative expression level of PtFT2 in PtFT2OE transgenic plants (#5, #8, #11 represent three independent transgenic lines). c: Bud set score of wild type (WT) and PtFT2OE plants in response to short day length. Data shown are mean values from six plants of each line. Error bars refer to ± SD. d: Overall phenotype of WT and PtFT2OE plants at 5 weeks after transferring from LD18h to SD8h conditions. e: Shoot apical morphologies of WT and PtFT2OE plants at 5 weeks after SD8h treatment. WT plants have ceased growth and formed buds, while PtFT2OE are actively growing."

Fig.S2

Determination of PtELF3KO transgenic plants and indoor phenotyping a: Mutations at the sgRNA target sites of PtELF3a and PtELF3b in three independent PtELF3KO mutant lines. #1, #6, #23 represent three independent transgenic lines; Deleted nucleotides are depicted as black dashes, predicted protein length in these mutants are displayed below. b: Overview of WT (717) and PtELF3KO plants taken at 6 weeks after short-day treatment (SD8h, 8h light/16h dark, 22℃). c: Shoot apical morphology of WT and PtELF3KO plants taken at 4 weeks and 8 weeks after SD8h treatments, respectively. d?e: Leaf numbers and bud set score of WT and PtELF3KO plants after transfer from LD18h to SD8h. #1, #6, #23 represent three independent transgenic lines; Data shown are mean values from six plants of each line. Error bars ± SD."

Fig.S3

The growth status of WT, PtFT2OE and PtELF3KO plants under field conditions in the winter and the early spring (the second and third year) a: Temperature variation throughout the year from 2021 to 2025 in Wuhan. b: Overview of one-year old and two-years old field-grown trees of WT, PtFT2OE and PtELF3KO plants under field conditions. The photos were taken on Jan 13th, 2022 and Mar 28th, 2023, respectively."

Fig.S4

Field Validation for "Functional Evergreen” trees（the sixth year） a: Representing shoot morphology of WT, PtFT2OE and PtELF3KO plants in three seasons of autumn, winter and spring. b: Representative stem images of WT, PtFT2OE, and PtELF3KO plants taken on December 13, 2025. Bars=2 cm. c: Dynamic DBH growth for the three genotypes. Data points represent measurements from 8–9 independent plants per genotype (with 2–3 biological replicates per transgenic line). Solid lines indicate fits to the Richards growth model. Error bars denote ± SD. DBH increased with age before stabilizing in all genotypes. d: Dynamic carbon storage for the three tree genotypes. Data points represent measurements from 8–9 independent plants. Solid lines indicate fits to the Richards growth model. Error bars denote ±SD."

Table 1

Primers used in this study"