Effects of Nitrogen Form and Concentration on Yield and Quality of Cucumbers Grown on Rockwool During Spring and Winter in Southern Greece

Abstract

ABSTRACT The influence of nitrogen concentration and the ratio of NO3 to NH4 on the marketable yield and fruit quality characteristics of cucumbers (Cucumis sativus L. cv. Palmera) grown on rockwool during spring and winter in southern Greece were studied. Nitrogen (N) was supplied at three N concentrations and four ratios of NO3 to NH4. During the spring, increasing total nitrogen or NH4 concentration within the nutrient solution significantly decreased the mean total yield and fruit size. However, during the winter, the yield and number of fruits per plant were not affected by N concentration, but were reduced by increasing NH4:NO3 ratio. Fruits that were produced under low N concentrations were lighter in color, but only the color of the apical tissues of the fruit was affected by the NH4:NO3 ratio. Flesh firmness of the fruit was not affected by N source or concentration, except for the apical tissue, the firmness of which declined with increasing N concentration. On the basis of the present results, for highest yield and fruit quality during both the spring and winter seasons of southern Greece, 100 ppm N applied solely in the form of NO3 is indicated.