“…A number of models have been developed to simulate the production of lettuce dry matter (Sweeney et al, 1981;Critten, 1991;Van Henten, 1994;Pearson et al, 1997;Seginer et al, 1998). A two-compartment mechanistic model originally proposed by Sweeney et al (1981) has been validated and extended by others (Van Henten, 1994;Van Henten and Van Straten, 1994;Pearson et al, 1997), who found that it could make reasonable predictions for lettuce dry matter accumulation.…”