Diferencias genotipicas en la eficacia de la nutrición nitrogenada en plantas de pepino (Cucumis sativus L.)

Two cultivars of the cucumber plant (Marketmore and Pepino de China) supplied with two total N levels (14 and 7 mol m -3 ) and a NO 3 - /NH 4 + ratio of 60/40 were grown aeroponically in a glasshouse. In order to known the N efficacy differences between the cultivars, several parameters were chosen, such as dry matter production; the ratio of root/shoot weight; NR activity; commercial yields; NO 3- , NH 4+ and total N consumptions; leaf and root concentrations. The results obtained displayed that Marketmore produced higher yields and lower vegetative weigth than Pepino de China, showing furthermore the highest ratios of fruit weight, NO 3 - ,NH 4 + and total N consumptions for the treatment with 7 mol m -3 of total N. The data obtained can be used for an adequate selection of cultivars characterized by a high N efficacy even for low N amounts.