DEFICIÊNCIA DE Ca, Mg e S E OS EFEITOS NA SÍNTESE DE ISOFLAVONAS E NAS TROCAS GASOSAS DE MUDAS DE EUCALIPTO

Abstract

The aim of this study was to evaluate the effects of calcium (Ca), magnesium (Mg) and sulfur (S) deficiency on isoflavone synthesis and gas exchange in Eucalyptus urophylla seedlings (clone AC 144). Conducted at the Federal University of Mato Grosso do Sul (UFMS), the experiment used a randomized block design with four treatments: complete solution and Ca, Mg and S deficiency, with seedlings grown in a greenhouse in washed sand substrate. Gas exchange was evaluated by a portable gas analyzer (IRGA), while the green color index was measured with a chlorophyll meter and isoflavones quantified by liquid chromatography. Analysis of variance (ANOVA) revealed significant effects of the treatments on physiological and biochemical variables. The results indicated that Mg deficiency was the most detrimental, reducing photosynthesis, green color index and dry biomass. The absence of Ca increased stomatal conductance and transpiration, but stimulated the production of isoflavones as an adaptive response to nutritional stress, while S deficiency caused a moderate impact, reducing water use efficiency and biomass accumulation. The complete treatment showed the best results, highlighting the importance of nutritional balance for adequate seedling growth and development. Correlation analysis showed positive interactions between biomass and Ca, Mg and S accumulations, in addition to associations between isoflavone production and seedling development. It was concluded that Mg deficiency significantly affects physiological performance, while the absence of Ca and S has a moderate impact, reinforcing the need for adequate nutritional management to optimize plant development and resistance.