Portable meters for nutritional assessment in plants of gerbera fertigated with electrical conductivity levels - Mota, Poliana Rocha D'Almeida; Villas Boas, Roberto Lyra; Ludwig, Fernanda; Fernandes, Dirceu M; Folegatti, Marcos Vinícius (Revista Brasileira de Engenharia Agrícola e Ambiental, 2014)