Variations in fruit micronutrient contents associated with fertilization of cucumber with macronutrients Diego A. Moreno, Gemma Vı ´llora, Luis Romero * Facultad de Ciencias, Dpto. Biologı ´a Vegetal, Universidad de Granada, Fuentenueva S/N E-18071, Granada, Spain Accepted 25 July 2002 Abstract Rates of N, P and K were used to compare the effects on iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and chloride (Cl) as well as the response of some biochemical indicators of micronutrient status in leaves and fruits of greenhouse-grown cucumbers (Cucumis sativus L. cv. Brunex F 1 ). The treatments were as follows: NH 4 NO 3 (5, 10, 20, 40 g/m 2 ); PO 4 H 3 (8, 16 g/m 2 ); and K 2 SO 4 (20, 40 g/ m 2 ). Control plants were supplied only with organic matter (manure from plant debris). The treatments N20, P16 and K40 favored the highest leaf biomass, whereas N40, P8 or P16 and K40 produced the lowest fruit biomass. The best treatments to promote phytoaccumulation of Fe and Mn in fruits were N10, P16 and K40. The fruit Cu, Zn and Cl accumulations were increased by fertilizer compared to the control. Foliar and fruit catalase activities help to indicate the nutritional status of Fe and Mn in cucumber, but, peroxidase and ribonuclease activities did not by themselves prove sufficiently informatives. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Bioindicators; Cucumis sativus; Fertilizers; Micronutrients 1. Introduction Plant fertilization is dominated by the need to provide crops with N, P and K, which promote plant development and increase the uptake of nutrients required by the plant (Ruiz and Romero, 1998; Kuangfei et al., 1999). In addition, the widespread use of macroelement fertilizers to raise crop yields makes them a convenient vehicle to supply crops with Scientia Horticulturae 97 (2003) 121–127 Abbreviations: CAT, catalase activity; DM, dry mass; Fe-EDDHA, ethylene-diamine (o-hydroxiphenyl) diacetic acid; FM, fresh mass; POX, peroxidase activity; RN, basal ribonuclease; RN þ Zn, Zn induced ribonuclease * Corresponding author. Tel.: þ34-958-243-255; fax: þ34-958-243-254/248-995. E-mail address: lromero@ugr.es (L. Romero). 0304-4238/02/$ – see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0304-4238(02)00147-4