Ammonium Toxicity Alleviation by Silicon is Dependent on Cytokinins in Tomato cv. Micro-Tom

The objectives were to verify the effects of lack cytokinins (CKs), comparing tomato cv. Micro-Tom (MT, wild type) MT CKX2 (transgenic with less CKs) fed nitrate (NO3?) and ammonium (NH4+), in presence absence silicon (Si); if attenuation NH4+ toxicity by Si depends on increase CKs MT; 6-benzyladenine (6-BA) attenuates MT. Three experiments performed treatments via nutrient solution. First, grown NO3? or (5.9 mmol L? 1), (1.28 1). Second, was Third, 1) 6-BA (from 1e?10 1e?6 mol L?1) associated NH4+. had a decrease 18% 48% shoot dry weight, respectively, when NH4+, compared NO3?. attenuated MT, but not CKX2. This accompanied trans-zeatin (tZ) content roots shoots. did improve growth In conclusion, alleviation dependent tZ CK-deficient plants, alleviate toxicity,