Influence of Vermicompost on the Concentration of Exogenous Indole-3-Acetic Acid and Its Effect on the Development of Tomato Plants (Lycopersicum esculentum L.)

Abstract

Exogenous auxins such as indole-3-acetic acid (IAA) can modulate the effect of a plant's endogenous auxins. The objectives of this work were to quantify the concentration of IAA in sand-based substrates with vermicompost (S-VC), to establish the relationship between the concentration of exogenous IAA and the amount of vermicompost (VC), as well as determine its influence on the development of tomato plants. S-VC substrates with different percentages based on volume (0, 20, 40 and 50% VC) placed in pots, with five replicates and randomly distributed, were used to transplant tomato seedlings. In each substrate, the concentration of IAA was determined at the beginning and at the end of a culture cycle, as well as the microbial load; In addition, some performance components were measured in the plants. The results showed that gram-positive bacteria were found in the substrates with VC, whose colony-forming units were related to the concentration of IAA and the amount of VC in the substrates. Therefore, the IAA concentration presented a linear and positive relationship with the amount of VC in the substrates (R2 = 0.9171, at the beginning and R2 = 0.9712, at the end of the experiment).