Effects of water and mineral nutrient deficiencies on pyrrolizidine alkaloid content of Senecio vulgaris flowers

The flowers of Senecio vulgaris contain the alkaloids senecionine, seneciphylline, and their N-oxides, compounds which are toxic to some grazing animals. Deficiencies of water, mineral nutrients, or both did not significantly alter concentrations of the individual alkaloids. However, more favourable growing conditions resulted in a greater quantity of flowers, which animals find quite palatable, so that each of these plants was potentially more toxic because it contained a larger total amount of the alkaloids.