IAA and SA Impact on Growth and Antioxidant Activity of Three Sewage Sludge-Treated Broad Bean Cultivars

Document Type : Original Article

Authors

Department of Botany and Microbiology, Faculty of Science, Minia University, Minia, Egypt

Abstract

 Sewage sludge (SS) can be used as a beneficial fertilizer due to its high contents of organic matter, macro and micronutrients. It also decreases soil pH which affects the availability and absorption of several nutrients and affects soil microbial communities. However, SS can also be toxic to cultivated crops. In this work, three broad bean cultivars (Sakha 1, Giza 843 and Giza 716) were cultivated in different SS levels (0, 20%, 50%, 70% and 100%) to evaluate and compare their responses. Treated plants were also tested for spraying by IAA and SA. Lengths of roots and stems, number of leaves, leaf area and fresh weights of roots, stems and leaves were measured. Antioxidant activity by the DPPH assay, contents of ascorbic acid, anthocyanins, free and bound phenolics and flavonoids were assessed to evaluate the impact of different treatments on the antioxidant system. SS treatment stimulated vegetative growth of cultivar Sakha 1 plants up to 1.5-fold that of control plants, while significantly suppressing the growth of the other two cultivars Giza 843 and Giza 716. Phytohormonal treatment alleviated the toxic SS effect on cultivars Giza 843 and Giza 716 while inhibiting the growth of SS-treated Sakha 1 plants. Stimulated growth was accompanied by enhanced antioxidants and vice versa. Therefore, SS can be used as a beneficial fertilizer for broad bean plants; however, cultivar selection is crucial as cultivars of the same species might respond differently. Phytohormonal spraying could be used to alleviate the adverse effects of cultivation in SS soil.   

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