Avaliação do efeito do peróxido de hidrogênio exógeno na germinação e crescimento inicial de Lactuca sativa L.

Abstract

Hydrogen peroxide is a reactive species of oxygen produced in cellular metabolism when the cell is subjected to stress situation, in its exogenous form this substance has been widely used for various activities, including bleaching techniques in the textile industry, treatment of industrial effluents and domestic activities. With this, exogenous H2O2 at low concentrations is able to positively influence plant growth, and in the literature little is known how this substance at high concentrations can affect the development of species and how much of it is necessary for 50% inhibition of root growth to occur. With this, the present study aimed to evaluate possible safe concentrations of H2O2 during the initial development of Lactuca sativa L. For the assembly of the experiment, 25 seeds and 3 mL of the aqueous solution of H2O2 were added at the concentrations of (1.065 mM), 0.25% (v/v) ; (2,131 mM), 0.5% (v/v); (4.262 mM), 1%, (v/v) and (5.327 Mm), 1.25% (v/v), and a control group containing only distilled water. Each treatment consisted of 4 repetitions. Seed germination was evaluated for 7 days and subsequently measurements of the length of the hypocotyl and radicle of the seedlings were made, and analysis of photosynthetic pigment levels of the control group and concentration of 1.25% v/v (5.327 mM). The group treated with 0.25% v/v (1.065 mM) did not present the development of the radicle affected by the substance, while all other treatments affected the initial development of seedlings, both in the radicle and hypocotyl, since the concentration of 1.980 mM has already decreased and the root growth of plants has already occurred. . There was a significant decrease in chlorophyll a and b levels, as well as carotenoides at the concentration of 5.327 Mm, 1.25% (v/v) compared to the control group. This information helps control the appropriate concentrations of H2O2 released into the environment, so as not to cause imbalances in ecosystems.