Influence of amino acids in the hydroponic medium on the growth of tomato plants

The effect on the growth of tomato plants (Lycopersicon esculentum Mill, cv Asun) of adding amino acids to Hoagland's nutritive solution, after ascertaining that a 50 mg L-1 dose of three antibiotics was sufficient to limit micro-organism-plant competition for the nitrogen supplied, was studied. The experiment consisted of four treatments, T0 (control, Hoagland's solution), T1 (amino acids, Hoagland's solution plus a mixture of 0.2 mM each of serine, alanine, tyrosine, and phenylanine), T2 (antibiotics, Hoagland's solution plus a mixture of Ampicillinum trihydricum, Streptomycini sulfas, and Gentamicyni sulfas, 50 mg L-1 of each antibiotic), and T3 (antibiotics and amino acids, Hoagland's solution plus a mixture of all antibiotics and amino acids). The relative growth rate (RGR) increased for the plants grown in T0 and T1, with the increase being significantly less in T1 compared with the control (T0), and was reduced for the plants grown in T3 and T2. The parameters absolute growth rate (AGR) and relative growth rate (RGR), demonstrated the negative effect of the antibiotics that cannot be mitigated by the presence of the amino acids (T3). Leaf stomatic conductance and transpiration values fell in all of the treatments. Daily water consumption increased in T0 and T1. At the end of the experiment, T2 and T3 plants consumed approximately 10% of the maximum value (93.8%).