SUMMARY Lettuce growth under cover of perforated polyethylene low tunnel in the Subtropical Central Region of the Rio grande do Sul State, Brazil, was evaluated. Treatments, applied on 1.00m x 12.00m x 0.10m nurseries, were polyethylene low tunnels with 0.78% (T1), 1.57%(T2), 2.35% (T3), and 3.14% (T4) perforated area, and the control, without tunnel (T). White Boston and Hampson lettuce cultivars were used in winter season (05.23.91 to 08.08.91) and in spring season (08.30.91 to 10.30.91), respectively. Parameters of steam and leaf number, and steam lenght were measured throughout experimental period. The results showed that T1 allowed the highest lettuce growth during winter season and during spring season T3 was the best treatment.
low tunnels; perforated plastic; lettuce
