Cobalt‐induced stress in tomato plants: Effect on yield, chlorophyll content, and nutrient evolution

An experiment developed in soilless culture was used to study the effect of several levels of cobalt (Co) (0, 5, 15, and 30 mg.L‐1) on yield and nutrient evolution of the tomato fruits (Lycopersicon esculentum M. cv. Ramy). The incidence of this pollutant in leaf chlorophyll contents was also studied. Increasing concentration of Co in nutrient solution reduced drastically yield in tomato plants. Total, a and b chlorophyll contents were affected by Co level in nutrient solution. A significant increase of nitrogen (N), phosphorus (P), calcium (Ca), and copper (Cu) in the fruit in function of Co treatments were observed. Similar evolution in iron (Fe) and manganese (Mn) fruit content affected by Co presence in higher treatment were obtained. No significant effect of Co presence on potassium (K), magnesium (Mg), sodium (Na), and zinc (Zn) fruit contents were observed. Cobalt absorption was very high, with values of Co in fruit around 250 μg Co g‐1.