Influence of calcium additions on heavy metals content and yield of navel orange trees irrigated with sewage water

摘要

Watching the content of heavy metals in fruits is one of the basic requirements for continuous applications of sewage water for irrigation of fruit trees. Calcium salts were used to ameliorate the accumulation of heavy metals in leaves and fruits ofNavel orange trees irrigated with sewage water. Two forms of calcium (CaCO_3 and CaSO_4) was added as soil application twice/year (early March and early May) in rates 150, 200 and 250 g/tree. The results obtained showed that of calcium have a positive effect on diminishing accumulation of heavy metals in leaves and fruits. In this respect, CaCO_3 recorded a more reduction of heavy metals accumulated in leaves, peel and juice compared to CaSO_4. Yet CaCO_3 should be used with caution, as it produced an adverse effect on yield with medium and high rates (200 g/tree and 250 g/tree).