Ammonium/nitrate ratio in the initial growth of Guaco

Guaco is a plant that has secondary metabolites with therapeutic properties of interest in human medicine, mainly due to its action in respiratory tract diseases. Nitrogen is a nutrient that participates in the formation of several compounds considered to be of great importance for plant growth. Its main forms of absorption by plants are ammonium (NH 4 + ) and nitrate (NO 3 - ) ions and unbalanced ratios can change plant growth. This study evaluates the effect of NH 4 + and NO 3 - (100:0; 75:25; 50:50; 25:75, and 0:100) ratios in nutrient solution on the initial growth of Guaco plants. Guaco growth was affected by NH 4 + and NO 3 - ratios. When NH 4 +  was supplied as the exclusive N source, Guaco plants reduced dry biomass production, number of leaves, leaf area, specific leaf area, leaf area ratio, total chlorophyll, and chlorophyll a and b indexes. Thus, increasing doses of the NO 3 - ion positively favored the initial growth of Guaco.