[Effect of Exogenous Chitosan on Physiological Properties, Antioxidant Activity, and Cadmium Uptake of Wheat (Triticum aestivum L.) Seedlings Under Cadmium Stress].

This research aimed to clarify the effects of exogenously applied chitosan on the physiological characteristics, antioxidant activities, and Cd accumulation of wheat (Triticum aestivum L.) seedlings under cadmium (Cd) stress and to identify the key indicators based on the partial least squares model. The wheat variety studied was Bainong207 (BN207), and Cd-stress was achieved by growing seedlings in a hydroponic culture experiment with 10 and 25 µmol·L-1 Cd2+ added to the culture solution. It was found that both Cd-stress at 10 and 25 µmol·L-1 significantly inhibited the chlorophyll content, photosynthesis, and biomass accumulation of wheat seedlings. Seedling roots became shorter and thicker, and the lateral roots decreased under Cd-stress. The Cd-stress also increased H2O2 and MDA accumulation and the degree of cell membrane lipid peroxidation and affected the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). Under Cd stress, exogenous chitosan decreased the Cd content in the aboveground and underground parts of wheat by 13.22 %-21.63 % and 7.92 %-28.32 % and reduced Cd accumulation in the aboveground and underground parts by 5.37 %-6.71 % and 1.91 %-4.09 %, respectively. Whereas exogenous chitosan application significantly reduced the content of H2O2 in roots and aboveground parts of wheat by 38.21 %-47.46 % and 45.81 %-55.73 % and MDA content by 37.65 %-48.12 % and 29.87 %-32.51 %, it increased the activities of SOD and POD in roots by 2.78 %-5.61 % and 13.81 %-18.33 %, respectively. In summary, exogenous chitosan can improve the photosynthetic characteristics and antioxidant enzyme activities of wheat seedlings under Cd stress, reduce the content and accumulation of Cd in the root and aboveground parts of wheat, and alleviate the damage of lipid peroxidation to the cell membrane. All of these results provide the basal data for the application of exogenous chitosan to alleviate Cd toxicity to wheat seedlings.

[Mitigative Effect of Rare Earth Element Cerium on the Growth of Zinc-stressed Wheat （Triticum aestivum L.）Seedlings].

This research aimed to clarify the mitigative effect of exogenously applied rare earth element cerium （Ce） on the growth， zinc （Zn） accumulation， and physiological characteristics of wheat （Triticum aestivum L.） seedlings under Zn stress. The wheat variety studied was Bainong307 （BN307）， and Zn stress was achieved by growing seedlings in a hydroponic culture experiment with 500 µmol·L-1 Zn2 + added to the culture solution. It was found that Zn stress at 500 µmol·L-1 significantly inhibited the chlorophyll content， photosynthesis， and biomass accumulation of wheat seedlings. Seedling roots became shorter and thicker， and the lateral roots decreased under Zn stress. The Zn stress also increased MDA accumulation and the degree of cell membrane lipid peroxidation and reduced soluble protein contents and the activities of antioxidant enzymes such as superoxide dismutase （SOD）， catalase （CAT）， and ascorbate peroxidase （APX）. On the contrary， exogenous Ce decreased the adsorption and transport of Zn by the root system and alleviated the damage of Zn stress to wheat seedlings. Specifically， the increase in chlorophyll content （chlorophyll a， chlorophyll b， and total chlorophyll） and photosynthetic parameters， the enhancement of antioxidant enzymes activities and soluble protein levels， and the reduction in MDA content and the damage of lipid peroxidation to the cell membrane were all driven by exogenous Ce， which ultimately led to the increase in dry matter biomass of the root system and shoot. In summary， these results provide basic data for the application of exogenous Ce to alleviate Zn toxicity to plants.