HUMIC ACIDS EFFECTS ON PLANT GROWTH AND PROTECTION AGAINST WATER STRESS IN SELECTED NATIVE MAIZE POPULATIONS FROM MEXICO

Abstract

Humic substances stimulate the growth and development of plants, inducing oxidative regulation at the cellular level in their interaction with the root surface. This promotes a state of “eustress” that results in root growth and protection of plants against abiotic stress. This study aimed to evaluate the effect of the application of humic acids (HA) in the germination and vegetative phases, with and without water stress induced by withholding irrigation, in selected native maize populations (Zea mays L.) from regions with drought incidence in Oaxaca, Mexico. The soil used had a neutral pH value, sandy loam texture and low organic matter content. Initially, HA delayed germination of maize seeds; subsequently, stimulation was recorded at the highest concentrations. The Cuilapam population showed the best response to HA application in this phase. In V7 vegetative phase, HA stimulated plant growth, promoting higher values in plant height, number of roots and production of root and shoot biomass, and attenuated the effect of water deficit in the three maize populations. The magnitude of the response was a function of the maize population and the concentration of HA applied. The application of HA reduced the adverse effects caused by the induced wter stress by enhancing growth parameters and protein synthesis in the three maize populations.