Resumo

CEPEDA-GUZMAN, Alejando et al. Lettuce response to electrical conductivity with surface irrigation and sub-irrigation systems. Rev. Mex. Cienc. Agríc [online]. 2014, vol.5, n.7, pp.1233-1245. ISSN 2007-0934.

Salinity suppresses plant growth and reduce agricultural productivity due to a water deficit, ion toxicity, causing nutrient skewness. A sub-irrigation system on principle, is based on capillary rise of water, up to the root zone, decreasing nutrient leaching compared with traditional watering systems. In void areas of northern Mexico, there are often high levels of calcium (Ca), magnesium and sulphate in irrigation water, directly affecting the electrical conductivity (EC). This paper proposed to evaluate the effect of EC on the growth of lettuce plants using two types of irrigation systems: surface and sub-irrigation. The diameter of the plants was bigger in plants with surface irrigation system compared to those with sub-irrigation; however, plants sub-irrigated with solution 3.3 dS m^-1 showed a higher fresh weight than those with surface irrigation, so this system is a good option to meliorate the effect of salinity. The rate of photosynthesis, transpiration and leaf conductance were not altered by the irrigation system at all, but transpiration and conductance were higher in sub-irrigated plants. A higher EC of the nutrient solution increased the bottom EC of the substrate, and the middle and top layer, and the surface irrigation system was higher compared to that presented by sub-irrigation. High EC of the nutrient solution did not attain the concentration of nitrogen or phosphorus whatsoever, but at elevated EC of the substance, the foliar potassium concentration did increased.

Palavras-chave : soilless crops; nutrition; salinity; stress tolerance.