Field-grown <i>Pro_35S</i>:<i>CO1</i>, <i>Pro_35S</i>:<i>CO2</i>, and control trees were observed for the onset of reproduction for five years, evaluated for the number of reproductive buds or catkins at age 5, and measured for height, diameter, and shoot growth at age 5.

Differing letters to the right of the mean (superscript) within a row represent a statistical difference (P≤0.05) between the average control and average transformant. Height was measured in meter (m), whereas diameter and shoot length were measured in centimeter (cm).