Parsley Extract Improves Physio-biochemical Traits and the Activity of the Defense System in Mallow (Corchorus Olitorius L.) Under Na₂SO₄ Salinity

Salinization of the agricultural soil, caused by natural factors or human activities, is one of the greatest challenges facing food production in the current time, as it negatively affects soil construction along with growth and yield of crops. In this study, an experiment was conducted on mallow plants (Corchorus olitorius L.) growing in pots to determine the effect of Na₂SO₄ stress on growth, physio-biochemical attributes, as well as antioxidative response, and the effect of parsley extract on salinity stress. Treatments consisted of 100 mM Na₂SO₄ and 10% parsley extract as single or combined treatments. Na₂SO₄ stress significantly reduced the plant growth, photosynthetic pigments, amino acids, glycinebetaine (GB), tannins, glutathione reductase (GR), ascorbic acid (AsA), and DPPH activity, while it significantly increased soluble sugars, proteins, proline, malondialdehyde (MDA), phenolics, catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH), total antioxidant activity (via phosphomolybdate assay (PMA)) and reducing power activity (RPA). Pre-soaking of mallow seeds in parsley extract enhanced growth, pigments, phenolics, tannins, CAT, GST, DPPH and RPA compared to salt-stressed plants. Integrative treatments of parsley with Na₂SO₄ remarkably increased growth, pigments, sugars, GR, GST, DPPH and RPA of stressed plants, but these treatments declined proteins, amino acids, proline, GB, lipid peroxidation (MDA), tannins, CAT, SOD and GSH in stressed mallow plants. Moreover, priming with parsley extract restored the ionic homeostasis in salt-stressed mallow. The results of this study recommend pre-soaking of mallow seeds in parsley extract to confer mallow growth in moderate saline soils.