Phenolic and oxidative metabolism as bioindicators of nitrogen deficiency in French bean plants (Phaseolus vulgaris L. cv. Strike)

The aim of the present work was to determine the effect of abiotic stress, such as nitrogen (N) deficiency, on phenol and oxidative metabolism. In add ition, we analyzed whether the response of the two metabolic processes is a good bioindicator of N deficiency in French bean plants. The N was applied to the nutrient solution in the form of NH4NO3 at 1.35 mM (N1), 2.7 mM (N2 ) and 5.4 mM (N3), this latter dosage being considered optimal. The results indicated that application of 1.35 and 2.70 mM of N can be defined as subo ptimal or deficient, as it depressed foliar biomass of the French bean plan ts in our experiment. In addition, abiotic stress from the application of t hese N dosages stimulated the enzymes PPO, POD and CAT, and inhibited PAL a nd SOD activities, resulting in the lowest foliar accumulation of phenolic compounds and H2O2.