Phenological Synchrony, Parental Contribution, and Pollen Dispersal Pattern affects the Genetic Composition of Cupressus funebris Dwarf Seed Orchard Progenies

Context Cupressus funebris is a high - value conifer, is important for timber and ecological protection. In its seed production, optimizing parental composition in seed orchards and using “dwarfed” trees after topping are key to achieving high - yield and high - gain seeds. However, compared to traditional seed orchards, the parental contributions and pollen dispersal patterns in dwarfed seed orchards remain unclear. Aims By analyzing flowering synchrony, parental contributions, and pollen dispersal patterns in a dwarfed Cupressus funebris seed orchard, we investigated their effects on offspring genetics. Methods Using three years of flowering-phenology observations, we quantified flowering synchrony and identified the principal climatic drivers governing its variation. We further characterised the mating system within the dwarf seed orchard, estimated the gametic contribution of each parent to the offspring cohort, and finally compared pollen dispersal patterns between dwarf and non-dwarf orchards. Results Three years of monitoring revealed significant interclonal variation among parental ortets in the seed orchard with respect to both strobilus production and flowering phenology, indicating asymmetrical gametic contribution within the orchard. The low within-year synchrony index of male and female strobili is predominantly governed by clonal variation, as well as by significant effects of mean daily maximum temperature, mean daily minimum temperature, and cumulative precipitation during the flowering period. The offspring population in the dwarfed seed orchard maintained high genetic diversity but had inbreeding risk. Compared to the non - dwarfed orchard, spatial distance was a key factor affecting pollination success in the dwarfed one. After dwarfing, the spatial distribution of female and male cone flowers shifted downward, shortening the average pollen dispersal distance, reducing outcrossing rates, and increasing self - pollination probability. Conclusion Branch management and plant spacing in Cupressus funebris dwarfed seed orchards should be emphasized. Improving ventilation and light penetration, combined with flowering management, are essential management strategies.