Effects of Various Concentrations of Trichoderma harzianum Fungus on the Phytochemical and Antioxidative Properties of Cauliflower (Brassica oleracea.Convar.botrytis L.) in the Soils Contaminated with Lead

Today, the growing rate of soil contamination is a major environmental concern. The cohabitation between microorganisms and plants hasbeen in place for millions of years, and investigationsin this regardhave become an important research area. The preset study aimed to assessthe effects of variousconcentrations of lead (0, 50, and 100 mg/l) and Trichodermaharzianumfungus (5%, 10% and 15%) on cauliflowerin a factorial design using fully randomized blocks in three replications under the climatic conditions of Dehlamavillage in Shahroud, Iran.The research was conducted during2014-2015 to measure the levels of chlorophyll a, chlorophyll b, totalchlorophyll, carotenoid, phenols, and flavonoids, as well as the antioxidant properties of cauliflower. The results indicated that the highestlevels of chlorophyll a (75.723 mg/wet weight), chlorophyll b (27.378 mg/wet weight), and total chlorophyll (109.074 mg/wet weight) were associated with the interactive effects of the treatment with 5% Trichoderma and lead concentration of 0 mg/l. Furthermore, thehighest level of antioxidant properties (79.88% of free radicals) was associated with the interactive effects of lead at the concentration of 50 mg/l and treatment with 5% Trichoderma. The highest level of phenols (21.33 mg of Gaelic acid/dry weight) was associated with the interactive effects of the lead concentration of 100 mg/l and treatment with 5% Trichoderma and flavonoids(22.889 mg of quercetin/g/dry weight), as well as the interactive effects of the lead concentration of 50 mg/l and treatment with 5% Trichoderma. Since carotenoids are antioxidants and precursors of vitamin A, the desired levels of antioxidants were achieved with the parallel effect of other antioxidants, such as total phenols and flavonoids.