Soil and plant nutrient modifications in response to irrigation with CO² enriched water on tomato

A 'Bandera' tomato crop was established in Vitulazio (Southern Italy) in the summer of 1991. Four irrigation treatments were imposed, supplying plain (PW) and CO2 enriched water (CW) with daily and 3 times per week waterings. All plots received the same total irrigation amount, on the basis of the estimated Maximum Crop Evapotranspiration (ETc). Fruit concentration of Zn, Cu, Fe and Mn was initially increased by CW, then it was similar to the control (Zn and Mn) or lower (Cu and Fe). Leaf concentration of the same group of elements was also increased in the later growth stages. Ca and Mg in the earlier stages showed diminished concentrations in all plant parts in response to CW treatment; later on, slightly higher Ca content was found in the fruit and lower in the leaves, while fruit Mg content was decreased. Higher cations contents were found in the plant in response to the higher irrigation frequency and interaction with CW effect was detected in most of the cases: in the first period, leaf and fruit contents of all elements, except for Mg in the fruit, were increased by daily irrigation; in the second one, leaf content of all nutrients was also increased; fruit content of Mg, Ca and Zn was increased, while that of Cu, Fe and Mn was decreased.