Effects of two Lignosulfonate-Humates on Zea mays L. Metabolism

Two lignosulfonate-humates (a and b), derived by an industrial process from lignin, were chemically characterized and their effects on maize plants in terms of growth, nitrogen metabolism and photosynthesis were investigated. The biological effects of lignosulfonate humates were compared with those induced by a humic acid extracted from leonardite in order to better understand the complexity of their biological effects. Our results displayed that both lignosulfonate-humates (a and b) had a hormone-like activity and increased root and leaf growth. Moreover, all treatments increased the content of chlorophyll, glucose and fructose and enhanced the activity of Rubisco, glutamine-synthetase and glutamate-synthase. The observed intense biological activity indicated that lignosulfonate-humates and leonardite humic acid had a positive role on photosynthetic process of maize plants. In the light of these results, lignosulfonate-humates may be used as biostimulants to increase crop yield.