SOIL SALINITY INCREASE Cd UPTAKE OF LETTUCE (LATTUCA SATIVA L.)

Abstract

Soil salinity has been reported to stimulate to Cd uptake of plants, particularly when Cd bioavailability is poor. The present study assessed the effects of two salinity levels of irrigation water (0, 50 mM NaCl) on Cd availability and uptake of different lettuce varieties under growth three levels of Cd (0, 1.5 and 3.0 mg Cd kg(-1)) pollution level at greenhouse condition. Sixty days after planting, the shoots were harvested, and Cd, Cl- and mineral concentrations of plant were determined. Cadmium application without NaCl treatment positively affected plant dry matter, and the highest yield increase ratio was obtained from Chinese cabbage at 3 mg Cd kg(-1) pollution without NaCl salinity but salinity treatment without Cd pollution negatively affected growth and mineral content of lettuce. Increasing levels of NaCl caused increases in the phyto-availability of Cd, as indicated by a significant increase in the leaf concentration of Cd. Plant leaf Cd concentrations were significantly correlated with soil and leaf Cl- concentration. Increasing levels of NaCl under Cd pollution caused increases in the phyto-availability of Cd, Ca, Na, Mn, and Zn mineral content in leaves of lettuce plants except for K, Fe and Cu content. It can be concluded from the study that salinity treatment can increase Cd in the phyto-availability of Cd, so grower must take into consideration Cd level in the soil under salinity stress condition.