EFFECT OF VANADIUM ON LETTUCE GROWTH, CATIONIC NUTRITION, AND YIELD

Lettuce plants (Lactuca sativa L.) cv. 'grandes lagos' were cultivated in nutrient solutions containing 0 (control), 0.1, 0.2, 0.5 and 1 mg/ kg of vanadium. Root and leaf growth (expressed as fresh and dry weigh ts) was inhibited by doses 0.2 to 1 mg/kg V. Yields decreased with inc reasing rates of vanadium. Toxicity symptoms in the roots consisted of color darkening, club shape of the main roots, reduction of secondary root number and length, and necrosis. Leaves from plants treated with 0.5 and 1.0 mg/kg V also showed turgidity loss. Vanadium accumulated in the roots and was poorly translocated to the leaves. All the treatm ents significantly increased vanadium root levels, but it augmented in the leaves only at the higher doses. Vanadium affected positively fol iar Ca and Fe concentrations, but it depleted K and Mg levels of the r oots. 0.1 and 0.5 mg/kg vanadium in the nutrient solution decreased Mn in the roots, whereas the highest dose raised it.