The aim of this study was to estimate the plot size for the lettuce crop grown in greenhouses, tunnel and field. The following experiments were carried out with this crop: 1) in greenhouse in summer; 2) in the field in summer; 3) in greenhouse in winter; 4) in the field in winter; 5) in greenhouse in autumn; 6) in tunnels in autumn; 7) in greenhouse in spring and; 8) in tunnels in spring. We evaluated the fresh and dry biomass of the shoots. We simulated plots of different sizes, from which we estimated the parameters necessary to estimate the plot size. We used the modified maximum curvature method to estimate the optimum plot size, and the least significant difference between means was obtained by the method of Hatheway. In order to test the homogeneity of variance between the rows of cultivation we applied the Bartlett test. The parcels shall be arranged in the direction of the crop row. In a simple recommendation, the optimum plot size for lettuce, regardless the variables fresh or dry weight as well as the season of cultivation, is of eight plants in the greenhouse and tunnel experiments, and nine plants for field experiments.
Lactuca sativa; protected environment; planning; precision experiment
