An Analysis of the Effect of Guayakí Yerba Mate on Plant Growth

Abstract

Despite the documented negative effects of caffeine on plant growth, gardening experts recommend watering plants with black coffee since coffee contains nutrients also found in plant fertilizers. The objective of our study was to determine whether varying dilutions of another common caffeinated drink, Guayakí Yerba Mate (GYM), would promote shoot growth in green onions. In this experiment, green onions were watered with different dilutions of GYM (25%, 50%, 75%, or 100% concentration) for our treatment groups and tap water for our control group. We hypothesized that if GYM is beneficial for plant growth, then the green onions placed in the 100% GYM solution would have the greatest shoot growth after a two-week period compared to the green onions in the diluted solutions and tap water. The mean shoot growth for each group was as follows: control = 24.2 cm, 25% = 10.13 cm, 50% = 4.96 cm, 75% = 4.12 cm, 100% = 3.02 cm. A one-way ANOVA test followed by a Tukey’s multiple comparison test showed that the mean shoot growth of the control group was significantly greater than each of the four treatment groups (p<0.0001). In conclusion, our hypothesis was not supported, and we found that GYM negatively affected the growth of the green onion shoots due to the impairment of root growth and function.