LAUSR

Abstract This article describes the effects of exogenous spermidine on mineral components, polyamines, total phenolic compounds, sugars, antioxidant activity and the percentage protein content in cauliflower florets under three different levels of heat stress. The combination of heat stress and foliar application of spermidine increased the antioxidant activity, total content of phenolic compounds and polyamines. It is worthy of note that histamine was detected in this work. The contents of all the soluble sugars measured were reduced when only heat stress was applied, but the contents of inositol, fructose and sucrose were increased after foliar application of spermidine at high temperature. Heat stress and spermidine application also produced an increase not only in the percentage content of proteins, but also in the K and P contents. Sulphate and phosphates were accumulated at ambient and extreme temperature, whilst nitrate was, in general, accumulated when 4 mM spermidine was applied.