Irrigation water quality in smooth lettuce cultivation

Resumo

Qualitative characteristics of surface and groundwater resources have been poorly verified by agricultural producers, who often irrigate their crops with contaminated water. This work aimed to analyze the quality parameters of two water sources (cistern and Brejão Lagoon) used by vegetable producers around the Brejão Lagoon in Sete Lagoas (MG) and to evaluate the influence of water quality on the growth of butterhead lettuce. Physico-chemical and microbiological analyses of the water sources used for irrigation were carried out, in addition to evaluating the height of the plants. The results of the physical-chemical analyses showed that the water studied is contaminated with fecal coliforms, 16.0 NMP (most likely number) in both samples, but at levels acceptable for Conama. For the electrical conductance, the water from the Brejão Lagoon presented a value of 119.7 mg L^-1what is about 6 x greater than that observed in the water from the cistern, which presented a value of 18.89 mg L^-1. The quality of the irrigation water did not influence the growth of butterhead lettuce. The pH of the two irrigation water sources used, fit in the values established by Conama. The vegetables’ irrigation sources are contaminated with microorganisms of fecal origin, but that contamination is still within the levels acceptable by Conama. Leafy vegetables can be used as a vehicle of infection for producers and consumers. According to the value determined for the electrical conductivity by Cetesb, the water from the Brejão Lagoon is not within the determined standards.