The objective of this study was to investigate the effects of phosphogypsum (PG) amendment on the physiochemical proprieties of saline and agricultural soils along with the growth, productivity and antioxidant enzyme activities of tomato plants ( Solanum lycopersicum L.) grown on the amended soils under controlled conditions. Obtained results showed that the amendment of saline soil (H) by PG induced a decrease in pH as well as in electrical conductivity. However, for the non saline soil (MC), there was a decrease in pH associated with an increase in electrical conductivity. For both soils, PG amendment led to an increase in Calcium (Ca) and sodium (Na), and a decrease in potassium (K) in plant tissues. Cadmium (Cd), Zinc (Zn) and Chromium (Cr) contents in different parts of plants increased in proportion with PG concentration in the soils. Apart from Cd, all the analyzed metals in tomato fruit were found to be below the recommended maximum allowable concentration (MAC). Our results showed that PG application, at doses not exceeding 20%, seems to be beneficial for growth, photosynthetic activity and productivity of tomato plants as well as in decreasing salinity of saline soils. In these conditions, the use of PG could be a promising project for the rehabilitation of marginalized and saline ecosystems with either ornamental or non-fruit species. For both soils, a significant accumulation of MDA in shoots was detected, reflecting cell membrane damage especially when the PG amendment reached 20%. Beyond 20 and 40% PG, tomato plants developed an enzymatic antioxidant defense system in response to salinity and heavy metal stress. However, at 80% PG, enzymes activities were significantly inhibited.
Keywords: Antioxidant enzyme activities; Heavy metals; Phosphogypsum; Saline soil; Soil amendment; Solanum lycopersicum L..