Optimum nutrient range in cucumber (Cucumis sativus L. cv. Brunex F-1 plants): I. Nitrogen and phosphorus parameters

Cucumber plants (Cucumis sativus L. cv. Brunex F-1), were grown under contr olled greenhouse conditions at Almeria (Southern Spain). The experimental d esign consisted in 27 plots. The N, P, and K treatments were applied as fol lows: four doses of N (N1 = 5 g/m(2), N2 = 10 g/m(2), N3 = 20 g/m(2), N4 = 40 g/m(2)) as NH4NO3, two levels of P (P1 = 8 g/m(2), P2 = 16 g/m(2)) as H3 PO4, and finally two levels of K (K1 = 20 g/m(2), K2 = 40 g/m(2)) as K2SO4. The leaves and fruits were analysed to determine: N, NH4, NO3, total and i norganic P; nitrate reductase activity (NRA), foliar acid phosphatase activ ity (FAPC), amino acids and soluble proteins. From the yield and analytical data the optimum range of nutrient and physiological parameters were obtai ned. In leaves, most plots showed nitrate, ammonium, aminoacids, proteins a nd infiltrated NRA levels in the low interval, while endogenous and induced NRA, and organic N were in supraoptimal levels. Fruit levels of nitrate, a mmonium and aminoacids were in the sub- and optimal range, while proteins w ere in supraoptimal levels and organic N was in the optimal level. In leave s, inorganic P was in sub- and optimum range and total P was in optimal and supraoptimal levels. The opposite was found in fruits. Most plots showed s uboptimal levels of APA in leaves and fruits.