Influence of nitrogen, phosphorus, and potassium on pigments concentrations in cucumber leaves

Abstract

Cucumber plants (Cucumis sativus cv. Brunex) were grown under controlled conditions and submitted to an individual fertilization with different doses of N (N,= 5g/m²; N₂= 10g/m²; N₃= 20g/m°; N₄=40g/m²) in NO₃NH₄ form; P (P1= 7 g/m²; P2= 14 g/m²) in H₂PO₄ form and K (Kl= 20 g/m²; K2= 40 g/m²) in SO₄K₂ form. This fertilization was complemented with organic matter and micronutrients solution, these doses were standard throughout the plant biological cycle. Control plants were included in the experimental design. Cucumber leaves were picked every 15 days all along the plant cycle and they were subjected to the determination of chlorophyll a and b (Chi a, Chi b), carotenes and licopenes. Our results showed that N fertilization have induced an increase of 15% in Chi a respect to control plants in the case of N₃ treatment, whereas N₄ resulted in a decrease of Chi a. Chlorophyll b presented similar behavior than Chl a, 10% of increase was obtained in N₃. Carotenes behaved with the same manner than chlorophyll, while licopenes did not show any significant variation among treatments. Inversely, P fertilization induced a decrease of both chlorophyll in P₂ treatment, whereas the P did not affect accessory pigments concentration. K₂ treatment acted positively on chl a and carotenes levels, with 11% and 7% of increase respect to control plants respectively. Chl b did not present any significant differences within K doses. In summary, our results lead us to think that N affected pigments contents, specially photosynthetic pigments, and high doses of P have acted negatively on all the pigments studied.