In one experiment, tomato plants were grown under natural light or extended photoperiods of 14, 16, 20 and 24h. Compared to natural light, extended photoperiod treatments increased shoot fresh weight and yields of tomato plants by, respectively, 40–57% (P<0.05) and 15–20% (P>0.05). However, photoperiods longer than 14h did not further improve growth and yields. In the second experiment, tomato plants were exposed to a 14 or 24h photoperiod and clusters were either pruned to 1 fruit or not. Tomato plants exposed to continuous light (24h photoperiod) started developing leaf chloroses after 7 weeks of treatments. We observed that, for the first 5 to 7 weeks of treatments, tomato plants grown under continuous light had better growth and higher yields than plants receiving the 14h photoperiod. During the second half of the experiment, continuous lighting decreased the growth rate of tomato plants. At the end …