Interaction of Fe and Si On Some of Biochemical Characteristics of Chickepea (Pisum Sativum Cv. Wando) In Greenhouse Conditions

The chickpea (Pisum sativum) are an herbaceous annual plant, with a short growth period which gives the best result in a cool climate. Although, exictence of some heavy metals like iron in soil and nutritional solution are essential for growth of plants but the high concentration of them can be an inhibitor of growth and causing toxicity by creation of oxidative stress and increasing ROS toxicity. On the other hand, silicon can increase the yieid and quality of the crops under stress conditions caused by the toxicity of heavy metals such as iron, manganese and aluminum in plants. In this research, the effects of silicon in presence of several iron levels on some biochemical traits in chickpea were studied.

The experiment was conducted as a factorial based on a completely randomized block design which Si at three levels (0, 14 and 28 mg/l) from sodium metasilicate (Na2SiO3.5H2O) and Fe in three levels (0.05, 0.1 and 0.3 g/l) from iron chelate used at three replications in greenhouse conditions. Hoagland's solution was used as nutritional solution, the amounts of Si and Fe were added to it and then consumed. Biochemical traits such as total chlorophyll, total soluble protein, malondialdehyde (MDA) level, hydrogen peroxide (H2O2) concentration, and specific activity of catalase (CAT), guaciole peroxidase (GPX) and ascorbate peroxidase (APX) were evaluated.

The results showed that the interaction of Fe and Si on total chlorophyll, protein, hydrogen peroxide, CAT and APX were significant. The increasing of Fe concentration, chlorophyll and protein reduced but Si caused increasing of them. In other words, by application of Si, the effects of stress which caused by high concentrations of Fe diminished. In the interaction of Fe and Si on H2O2 content, Fe raised and Si decreased it at all the levels of the treatments. Both Fe and Si treatments increased the activity of CAT and APX enzymes. On the other hand, the interaction of treatments on GPX activity and MDA content were not significant. But the simple effects of the treatments caused significant differences in GPX and MDA, so that Fe increased both of them, but Si reduced MDA and increased GPX.

Based on the results, it can be concluded that high concentrations of Fe in chickpea, such as most plants, increase the oxidative stress and Si has somewhat reduced the effects of this stress. Therefore, Si can be studied and used as a useful ingredient in cutting down biotic and abiotic stresses. Based on this study, 0.1 g/l of Fe along with 28 mg/l had the best effect on improving some biochemical characteristics of chickpea.