Eucalyptus globulus Labill. ssp. globulus seedlings produced in containers under homogeneous morphological conditions were treated with short photoperiods of 8 hours for 7 and 15 days. The effect was compared with that of a normal photoperiod of 10 hours in a nursery (treatment control), and evaluated using three methods: the relative electrolytic conductivity (CER), the content of total soluble carbohydrates (CST), and root growth potential (RGP). The reduction of the photoperiod for 7 days significantly diminished the content of total soluble carbohydrates, but this increased to levels similar to the control after 15 days of the reduced photoperiod. There was no effect of photoperiod on the relative electrolytic conductivity or root growth potential.