Influence of nitrogen, phosphorus, and potassium on pigment concentration in cucumber leaves

Abstract

Abstract Cucumber plants (Cucumis sativus cv. Brunex) were grown under controlled conditions and submitted to an individual fertilization with different doses of N (N1 = 5 g/m2; N2 = 10 g/m2; N3 = 20 g/m2; N4 = 40 g/m2 ) as NH4NO3, P (P1 = 7 g/m2; P2 = 14 g/m2) as H3PO4, and K (K1 = 20 g/m2; K2 = 40 g/m2) as K2SO4. This fertilization was applied together with organic matter and a micron‐utrients solution, with doses standard throughtout the plant's biological cycle. Control plants were included in the experimental design. Cucumber leaves were collected every 15 days during the plant life cycle, bing assayed for their chlorophyll a and b (Chi a and Chi b), carotene, and licopene contents. Our results showed that N fertilization induced an increase of 15% in Chll a respect to the control plants for the N3 treatment, whereas the N4 treatment resulted in a decrease in Chi a. Chlorophyll b presented a similar behaviour as that for Chll a, with a 10% increase occurring with the N3 treatment. Carotenes behaved in a same manner as that for chlorophyll, while the licopenes did not show any significant variation among treatments. Inversely, P fertilization induced a decrease of both chlorophyll a and b with the P2 treatment, whereas P did not affect accessory pigments concentration. The K2 treatment acted positively on the chll a and carotene levels with an 11% and 7% increase as compared with the control plants, respectively. Chlorophyll b did not vary significantly due to the K doses. In summary, our results showed that N affected the pigment content, specially the photo synthetic pigments, while high doses of P acted negatively on all the pigments studied.