Chlorophyll contents in tomato cultivars under magnesium foliar applications

Abstract

Although the foliar nutrients application is well disseminated in horticulture, the technology is still controversial, since the products efficiency is related to the characteristics of the formulations, especially the sources of nutrients used. Thus, this study aimed at identifying changes in chlorophyll contents, by using the colorimetric method and a chlorophyll meter, as well as in the Mg content in tomato plant leaves, as related to foliar applications of solutions containing Mg (OH)₂ or MgCl₂. Two tomato cultivars were subjected to fertigation with low Mg addition. The data from the chlorophyll meter were corroborated by the colorimetric method, indicating that the solutions containing 1.0 mL L^-1 and 2.0 mL L^-1 of a suspension concentrate (300 g L^-1 of Mg, as Mg(OH)₂) and the solution containing 3.75 mL L^-1 of MgCl₂ were effective in increasing the chlorophyll contents, resulting in the Mg absorption and metabolization. The solution containing 7.5 mL L^-1 of MgCl₂ caused fitotoxicity and reduced the chlorophyll contents, although promoting a higher Mg content in leaves.