To understand the functions of exogenous 24-Epibrassinolide (EBR) in enhancing the salt tolerance of wheat (T. aestivum L.) seedlings to salt stress, a hydroponic experiment was performed to investigate the effects of EBR on chlorophylls, root activity, H + -ATPase, malondialdehyde (MDA), electrolyte leakage, free proline, soluble protein, reactive oxygen species (ROS), antioxidant enzymes and minerals content in wheat plants subjected to non-stress conditions or salt stress (120 mM NaCl) with foliar application of EBR (1, 10 and 100 nM). Results showed that spray of low concentrations EBR (1 and 10 nM) under non-stress conditions could promote wheat plant growth. 120 mM NaCl induced osmotic stress, oxidative stress and imbalance in mineral nutrients absorption. However, EBR enhanced the ability of resistance to osmotic stress by increasing free proline and soluble protein content, and enhanced the ability of resistance to oxidative stress by increasing antioxidant enzymes activities. As a result of increase of chlorophyll content, root activity and H + -ATPase activity, the inhibition of K, Ca, Mg, Fe and Zn uptake was ameliorated and consequently, decline in plant growth induced by NaCl stress was alleviated. Based on these results, we conclude that EBR had a positive role in regulating wheat growth and development under salt stress, and spray of 10 nM EBR had the most significant alleviating effect against NaCl toxicity.

A pot experiment was conducted to study the effects of sodium nitroprusside (SNP, a nitric oxide [NO] donor) on cadmium (Cd) toxicity in ryegrass plants. In the present study, ryegrass plants subjected to Cd toxicity were treated with different concentrations of SNP (50, 100, 300 and 500 µM), SNP solution was poured into Cdcontaminated soil every seven days. Cd treatment inhibited the plants growth and the absorption of micronutrients, increased accumulation of Cd in both shoots and roots. In Cd-treated plants, the activities of antioxidant enzymes and the contents of proline, soluble protein and ascorbic acid (AsA) decreased dramatically, whereas the accumulation of superoxide anion (O 2 .-), hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) increased significantly. Addition of SNP significantly decreased O 2 .-, H 2 O 2 and MDA accumulation in both shoots and roots of Cd-stressed plants, decreased the transport of Cd from roots to shoots, alleviated the inhibition of Ca, Fe, Mg and Zn absorption induced by Cd and promoted the plant growth. In SNP-treated plants, the chlorophyll content, the contents of proline, soluble protein and ascorbic acid, and the activities of superoxide dismutase, peroxidase and catalase increased considerably. Addition of 300 µM SNP had the most significant alleviating effect against Cd toxicity while the addition of 500 µM SNP had no significant effect with Cd treatment. Based on these results, we concluded that the optimal concentrations of exogenous SNP could alleviate Cd induced stress and promote ryegrass plant growth.