“MICORRIZAS, ALUMÍNIO E FERTILIZAÇÃO NA PRODUÇÃO DE MUDAS DE ERVA-MATE (ILEX PARAGUARIENSIS A. ST. HIL.)”

Abstract

Yerba mate (Ilex paraguariensis A. St. Hil.) naturally develops in acidic soils rich in aluminum (Al). Proper management of mineral fertilization is crucial for the initial development of yerba mate. Additionally, mycorrhizae can enhance the early growth of native forest species. This study aimed to evaluate the effects of mycorrhizal inoculation, mineral fertilization, and aluminum (Al) supply on the initial development of yerba mate. In the first experiment (Chapter I), treatments consisted of mycorrhizal fungi inoculation (with and without mycorrhizae) combined with different types and doses of mineral fertilization (controlled-release NPK fertilizer and nutrient solutions containing different doses of N, P, and K). In the second experiment (Chapter II), two substrate fertilization treatments (with and without fertilization) and seven doses of Al applied monthly to the substrate were evaluated. Plant growth assessments included measurements of shoot height and stem diameter at different times, as well as determinations of dry shoot and root mass, fresh root volume, and the Dickson quality index (DQI). Complete NPK fertilization provided in a nutrient solution resulted in the highest growth of yerba mate seedlings, followed by moderate doses of controlled-release NPK fertilization. Mycorrhizal inoculation increased the growth of yerba mate seedlings. Yerba mate seedlings exhibited high tolerance to Al in the substrate, withstanding monthly applications of up to 1000 mg dm-3 of Al3+ without showing toxicity symptoms. However, doses exceeding 2000 mg dm-3 of Al3+ caused toxic effects on yerba mate seedlings. This study concludes that Al does not benefit the initial growth of yerba mate. Nonetheless, proper mineral fertilization management, combined with mycorrhizal inoculation, promotes better initial development of yerba mate.