Evaluation of two aqueous plant extracts in protection of wheat against phytopathogen fungus, Helminthosporium rostratum

Abstract

In the field and greenhouses, chemical fungicides is the most commonly tool used for controlling fungal disease. Although chemical usage has been very effective in controlling fungal plant diseases, some major problems threaten to limit the continued use of fungicides. In the present research, extracts of Ziziphus and Rumex plants were chosen based on both traditional usages suggestive of antifungal activity. In addition, toxic fungal constituents of higher plants are generally thermo-labile, therefore, an aqueous extract was preferred for prevention any adverse effects. Phytochemicals of both plant extracts were detected by using HPLC, various phenolic and flavonoids compounds were detected. Ziziphus and Rumex extract concentrations that inhibited 50% of fungal growth (IC50) were 25 and 50 mg/ml, respectively. In vivo, results of morphological parameters of plant growth revealed that aqueous of tested plant extracts had allelopathy effects on seed germination. Increasing of plant roots length was appeared in the case of Ziziphus coated seed (either uninfected or infected). Both Ziziphus and Rumex aqueous extracts had positive synergistic effect where shoot lengths significantly increased. Dry weight of wheat spike significantly increased in Ziziphus and Rumex extracts treatments. Total proteins content of wheat plant were higher in all treatments than infected wheat plant with H. rostratum, on contrary, proline content. The results serve and support the new trend in biological control, where the aqueous extracts of Rumex and Ziziphus plants clearly reduced the effectiveness of fungal infection and improved all growth parameters of wheat seedlings (especially in the case of tri-treatments).