EFFECTS OF NUTRIENT AND WATER-STRESS ON LEAF PHENOLIC CONTENT OF PEPPERS AND SUSCEPTIBILITY TO GENERALIST HERBIVORE HELICOVERPA-ARMIGERA (HUBNER)

Pepper plants were grown under different water and nitrogen availabili ties that produced severe nitrogen limitations and mild water stress. Nitrogen limitation produced lower leaf N content, higher C:N, and hig her leaf content of phenolic compounds, in consonance with the carbon/ nutrient balance hypothesis. Nitrogen limitation also produced lower n utritional quality of leaves, with lower relative growth rates and low er efficiency of conversion of ingested biomass on the polyphagous her bivore Helicoverpa armigera. The biomass gained per gram nitrogen inge sted also tended to be lower in those insects feeding on nitrogen-limi ted plants, in parallel with their higher phenolic content. However, l arvae fed on nitrogen-limited plants did not increase the ingestion of food to compensate for the N deficiency of leaves. The mild water str ess, which only slightly tended to increase the phenolic content of pe pper leaves, had no significant effect on nutritional indices.