Development of Alternative Crop Systems for Commercial Production of Vegetables in Hydroponics - I: Tomato

The main results of a research line carried out over several years at Universidad Autonoma Chapingo are presented. The aim is the development of alternative soilless tomato (Lycopersicum lycopersicon Mill.) production systems to achieve short growing cycles. They are based in delayed transplant up to 60 days after sowing and in the plant decapitation above first, second or third inflorescence, eliminating the lateral buds. The results show that the lower yield per plant in a crop cycle with respect to traditional growth system, is compensated by the increase in plant density. Yield per surface unit in a crop cycle is lower, but the annual productivity is higher because up to five cycles per year can be obtained. Advantages with these systems are: escape to diseases, less pesticide use, lower installation costs and bigger fruit size. In this essay, the main results with different seedlings ages to transplant, population densities, decapitation levels, cultivars, substrates, containers, nutrient solutions, dose and watering intervals and dispositions of plants are reported. Using containers of 0.7 L filled with volcanic sand it is possible to transplant with seedlings up to 60 days age without negative effects in later development. With plants at densities of 16 to 18 plants/m(2) decapitated to a cluster, a mean yield of 12 kg/m(2) is achieved in a cycle of 70 days from transplant to final harvest; with 10 to 12 plants/m(2) decapitated to two clusters, an average of 14 kg/m(2) is obtained in 80 days, and with 6 to 8 plants/m(2) managed to three clusters a mean yield of 16 kg/m(2) is reached. The highest yield in a crop cycle (26 kg/m(2) in 90 days) has been reached with plants decapitated to three clusters distributed in rows at different height forming a canopy in stairway form.