Effect of chromium on seed germination, early seedling growth and chromium accumulation in tomato genotypes

Forty-five tomato (Solanum lycopersicum) genotypes were used for evaluating chromium (Cr) tolerance and Cr accumulation in seedling by in vitro culture. Tomato seeds were cultured on Murashige-Skoog medium supplemented with 1.5 mM Cr (K2Cr2O7) for four weeks. Reduced germination percentage and delayed germination during 14 days was observed in more than 90% genotypes as compared to the control, but only half of genotypes showed obvious decrease in seedling survival rate. Chromium treatment displayed significantly negative effect on shoot length in all genotypes but significant inhibitory on shoot dry weight was recorded only in 41 genotypes. The highest Cr accumulation in shoot was 3.92 mg g(-1) DW in 'M-82' and Cr accumulation greater than 2 mg g(-1) DW was found in 6 genotypes. Three genotypes ('LA3708', 'CLN2777H' and 'CLN1621L') showed higher Cr uptake (more than 9.8 mu g per shoot) than other genotypes because of their high biomass of shoot. Considering Cr tolerance (with higher germination rate, seedling survival rate and shoot biomass in Cr treatment) and Cr accumulation (higher Cr concentration and uptake in shoot) simultaneously, 'CLN2777H' and 'CLN1621L' can be suggested as the potential tomato genotypes for Cr phytoremediation of polluted sites.