Allelopathic potential aqueous extract of tubers of tiririca in the growth and development of lettuce

البرتغالية. Lettuce (Lactuca sativa) belongs to the asteraceae family, known worldwide and appreciated for generations. Due to the great acceptance, the lettuce is a vegetable of high consumption. In search of solutions for high productivity some techniques have been researched to reduce the stress suffered by the plant to the environment. This study aimed to verify that the aqueous extract of tiririca, in different strengths, present some allelopathic effect on the development of the lettuce. The use of the aqueous extract, which has in its composition the Indole Acetic Acid-AIA (Auxin), was used by capillary irrigation, with the following treatments: T0-control; T1- 25% of concentration; T2- 50% of concentration; T3- 100% of concentration. This study consisted of five replicates and five plants per treatment, with a total of 100 plants. The design was completely randomized. The analyzes were root size, shoot development by fresh mass plant, number of leaves and chlorophyll content. According to the data, it was observed that the concentration of the 100% root extract resulted in higher values of root development, however, affected shoot growth, a result verified in the fresh mass, in which the plants presented reduced weight when compared to the other treatments, and consequently affected the amount of leaves produced by the plants submitted to this treatment, the chlorophyll content was also lower for the plants treated with the maximum concentration of the extract. Therefore, it can be concluded that high dosages of the tiririca extract had an allelopathic effect inhibiting the growth and development of the lettuce plants, and did not present a satisfactory result.