In vitro antioxidant activity, macronutrients and heavy metals in leaves of maize ( Zea mays L.) plants grown at different levels of cattle manure amended soil in Jordan valley

摘要

A field experiment was conducted at the National Center for Agricultural Research and Extension in the Jordan Valley, during summer 2015 to evaluate the effect of cattle manure on antioxidant activity of maize leaves. The study also measured the effect of cattle manure on the bioavailability of heavy metals in maize leaves at harvest. Six treatments were compared, no cattle manure (T1, control), and 4 tons ha ?1 (T2), 8 tons ha ?1 (T3), 12 tons ha ?1 (T4), 16 tons ha ?1 (T5), and 20 tons ha ?1 (T6) cattle manure. ANOVA followed by LSD test were used to compare the treatments at the 5% significance level. Antioxidant activity using DPPH and ABTS were measured for the six leaves extracts representing six treatments of organic manure. A wet digestion method was used to extract the heavy metals from the dry leaf powder samples using atomic absorption spectroscopy. Antioxidant activity for leaves increased significantly with increasing cattle manure amount applied to soil according to DPPH and ABTS radical scavenging activity. The highest antioxidant activity was reached at the highest amount of cattle manure while the control had the lowest. Concentrations of Ni, Cu, Mn, Zn, Cr and Fe contents in maize leaves of plants grown in soil amended with cattle manure were higher compared to plants grown in no-amended soil. Cattle manure amended soil increased Ca, K and P concentrations in the seeds and leaves of maize. The cattle manure was able to encourage a raise on mineral buildup in aerial parts of tested plants.