Effect of Repeated Phosphate Fertilization on the Heavy Metal Accumulation in Soil and Plants Under Protected Cultivation

In order to study the effects of repeated phosphate fertilization under protected cultivation, tomato (Lycopersicon esculentum Mill.), radish (Raphanus sativus L.), celery (Apium graveolens L.), and lettuce (Lactuca sativa L.) plants were grown in subsequent cycles on the same substrate and fertilized with increasing amounts of superphosphate containing varying amounts of heavy metals. The accumulation of metals in the soil and the consequent increased uptake of metals by plants did not result in any reduction in the marketable production. The reduced plant yield observed in lettuce and in radish with the increase in the addition of superphosphate was most likely due to the increased salinity of the growth substrate, which affected the metabolic processes of the plants. The high concentration of salts as a result of the addition of high amounts of phosphorus fertilizer made it unadvisable to reuse the substrate under the experimental conditions adopted. © 1993, Taylor & Francis Group, LLC. All rights reserved.