MINERAL NUTRITION AND PRODUCTIVITY OF HYDROPONICALLY GROWN TOMATOES IN RELATION TO NUTRIENT SOLUTION RECYCLING

     Nutrient solution recirculation is often used to improve the use efficiency of mineral nutrients and reduce the contamination of soils and ground water outside the greenhouse. However, several ions may accumulate in the nutrient solution when recycled. This accumulation causes nutrient imbalances affecting both crop yield and quality. This study was aimed to determine the short-term effects of recirculation of the nutrient solution on foliar mineral composition and fruit yield of the greenhouse Roma type tomato. The experiment was conducted at the Instituto Tecnologico Agropecuario de Oaxaca. Ten-days-old tomato seedlings (Lycopersicon esculentum Mill. ‘SXT 7705’) germinated in 200-cell plug trays filled with peat-moss were transplanted into rockwool blocks. Four weeks after transplanting, young tomato plants were planted in two different soilless culture systems: NFT (Nutrient Film Technique) involving recirculation of the nutrient solution and substrate mix bags without nutrient solution recycling. In both culture systems, the nutrient solution was monitored and adjusted for pH and electrical conductivity and in NFT system, renewed every 4 weeks. There was a dramatic ion accumulation and salinity as well when the nutrient solution was recycled. Fruit yield and fruit quality were negatively affected by the recirculation of the nutrient solution in the short term.

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