Influence of Lead (Pb) and Its Relationship with the pH of Water on the Growth of Creole Maize (Zea mays L.)

Abstract

Lead (Pb) as a pollutant is not biodegradable, tends to accumulate in different organisms, and can affect, for example, the performance of maize crops. However, only a few studies have reported on the effect of lead (Pb) and the relationship with the potential of hydrogen (pH) of water on crop performance. Thus, this study aimed at determining the influence of Pb and its relationship with the pH of water on the growth of Creole maize (Zea mays L.). In order to achieve this, a double bottom vessel system, isolated from the soil, was used to expose the plants to an aqueous Pb solution based on the equivalence of 1.5985 g of lead nitrate (Pb(NO3)2) per g of Pb. An experimental design of the two-factor response surface methodology (RSM) was applied. The Creole maize plants were exposed to four different concentrations of Pb in water [0 g L−1 (P1: control); 0.33 g L−1 (P2); 0.66 g L−1 (P3); 1 g L−1 (P4)], as well as to three different pH levels (5.5 (pH1); 6.5 (pH2); 7.5 (pH3)) in clay soil typical of the region. Subsequently, the relationship of these variables with maize growth was determined. The results showed a decrease in leaf growth, height, stem circumference, and root. However, it was also determined that these negative effects can be mitigated by controlling the pH of water in 7.5. Failure to control the combination of these two factors in the cultivation process generally results in an impact on the growth of the maize seedling. In addition, leaf discoloration was also observed in the leaves of maize plants from the concentration of 0.33 g L−1 (P2), which suggests a nutritional anomaly that is toxic to the plant.