Uptake and distribution of selenium in tomato plants as affected by genotype and sulphate supply

Aim of this work was to investigate if the variation among tomato genotypes in selenium (Se) uptake and accumulation observed in short term experiment s are maintained over longer growth periods and if there is a positive corr elation in shoot between sulphur (S) accumulation and Se accumulation acros s different genotypes or if higher tissue S results in greater feedback inh ibition of Se uptake. Two experiments were carried out under greenhouse con ditions and different genotypes of Lycopersicon lycopersicum (UC82B and LA2 711) Lycopersicon pennellii (LA716) and Lycopersicon peruvianum (LA2157) we re grown until fruit ripening. The results obtained in the two experiments confirmed that sulphate in the growth solution reduced selenate uptake by p lants and increased the S content of the leaves. Under low sulphate treatme nt there was a clear correlation (R-2=0.82) between leaf S content and shoo t Se content across genotypes in both experiments, indicating that the over all activity of the S transport systems also determines Se transport. Selen ium was translocated from shoot to fruit, but the edible portion of the pla nt contained much less total Se than the inedible plant parts. The differen ce in Se content between the low and the high sulphate treatments was signi ficantly higher in shoot than in root, confirming that the Se translocation from root to shoot is probably more affected by high sulphate supply than Se uptake by root. In the first experiment the genotype LA716 showed an hig her Se accumulation together with higher S content in leaves, indicating a marked ability of this genotype to absorb ions from substrate. In the secon d experiment UC82B appeared to be more capable to accumulate Se and S rathe r than LA2711 and LA2157. In both experiments Lycopersicon peruvianum appea red to be less affected by the high concentration of ions in the growth sol ution and to be able to reduce ion uptake than Lycopersicon lycopersicum an d Lycopersicon pennellii.