ANNUAL GREENHOUSE TOMATO PRODUCTION UNDER A SEQUENTIAL INTERCROPPING SYSTEM USING SUPPLEMENTAL LIGHT

Greenhouse tomato plants (Lycopersicon esculentum Mill. cultivar 'Caruso') were grown in a sequential cropping system, intercropping the young plants between the mature plants. The four transplanting dates were 24 July, 2 November, 5 February and 19 April. The plants were cultivated on rockwool slabs and trained in a V-shaped system. The treatments were two levels of photosynthetic photon flux density (PPFD), 100 and 150-mu-mol m-2 s-1, supplied by 400-W high-pressure sodium (HPS) lamps during a 16-h photoperiod from September to May, and three plant densities: (a) low density, 2.3 plants m-2 for all four successions. The highest cumulative yields for the four successions (39 weeks picking) were 56 and 72 kg m-2 at 100 and 150-mu-mol m-2 s-1, respectively, for the variable planting density. Yields were respectively 14 and 34% greater at the high and variable densities than at the low density for the two light treatments. The higher PPFD treatment raised the total number of fruits picked by 10, 16 and 14% for the low, variable and high planting densities, respectively. With well-synchronized crops, at high-density plantings with supplemental lighting of 100 and 150-mu-mol m-2 s-1, annual yields of 70 and 84 kg m-2, respectively, are predicted.