Vasconcelos, Ernesto PestanaCabral, Fernanda Maria MirandaNeves, Bruno Miguel Pedroso2012-03-232012-03-232011Neves, Bruno Miguel Pedroso - Influência do molibdénio na acumulação de nitratos nas folhas de alface (Lactuca sativa L.). Lisboa: ISA, 2011http://hdl.handle.net/10400.5/4166Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaIn this study four field experiments and one pot experiment were conducted with the aim of studying the decrease of nitrate accumulation in the lettuce leaves. To achieve this objective the following issues were addressed: effects of molybdenum applied either in fertirrigation and/or foliar fertilization; the influence of different lettuce varieties and lines; the suppression of nitrogen fertilization; and the evolution of the soils characteristics. Results obtained allowed to draw the following conclusions on the effects of molybdenum: promotes the reduction of nitrate accumulation in the lettuce leaves although no significant differences were observed between fertilization methods; increases the productivity, specially when this micronutrient is applied by foliar fertilization and promotes nitrogen uptake in this form. It was concluded that the suppression of nitrogen fertilization led to the reduction of nitrate accumulation. It may be also concluded, that for the same climatic conditions, lettuces of different varieties and/or lines accumulate different nitrate contents, being the line „Emocion Rz‟ (var. capitata) the one that accumulates less nitrate and the line 'Ribai Rz' (var. acephala) the one that accumulates moreporlettucenitrate accumulationreduction of nitratemolybdeniumnitrate redutasenitrate assimilationmaster thesis