Effects Of Selenium On Growth And Activated Oxygen Metabolism And Nutrition Absorption Of Rape Seedlings Under Boron Stress

Brassica napus is one of the main economic crops in China and rape has a great demand for boron(B). B fertilizers is an important technical measure of rape yield. The appropriate B concentration range for crop growth is0.5-1mg/kg. Low-B concentration result in B deficiency, and high-B concentration easily lead to B toxicity. B deficiency always causes the decrease of crop yield and quality in the area of the middle and lower reaches of Yangtze River. At the same time, B toxicity is a significant constraint to cereal production in regions, including parts of southern Australia. An appropriate Se can improve crop resistance and beneficial for the growth. This paper aims to investigate the effect of B and Se on growth and activated oxygen metabolism and nutrition absorption of rapeseedlings. Solution and soil culture experiments were carried out using rape seedlings (Brassica napus L. cv. Xiang nong you571) as the test material. The effects of these treatments were assessed on rape seedling growth, B uptake and accumulation, reactive oxygen metabolism, nutrition absorption with application of B and Se. The main results were as follows:1. Alleviation of B toxicity on rape seedlings by an appropriate Se. Under B stress conditions, the dry weight of rapeseed seedling shoots and roots decreased significantly; B content and accumulated icreased significantly; The enzymatic activity of scavenging reactive oxygen species, including catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) in rape seedling leaves decreased, and the endogenous reactive oxygen substances (glutathione (GSH)) in leaves were significantly reduced, while hydrogen peroxide (H2O2) and malondialdehyde (MDA) increased significantly. The B-treated (500μmol/L) plants supplemented with Se showed increased shoot and root dry weight; Se at1μmol/L concentration significantly affected the B uptake and accumulation; The B-treated (500μmol/L) plants supplemented with1μmol/L Se showed improved CAT, POD and APX activities, GSH and ASA contents increased, while the accumulation of hydrogen peroxide and the increase of membrane lipid product malondialdehyde were effectively reduced. It was suggested that an appropriate Se can increase reactive oxygen metabolism of rapeseed and reduce the accumulation of reactive oxygen, thereby significantly decreasing the impact of excessive B on rapeseed growth and improving the adaptability of rape seedlings to excessive B.2. An appropriate Se can increase reactive oxygen metabolism and beneficial for the growth of rapeseed under B deficiency. Under B deficiency conditions, the dry weight of rapeseed seedling shoots and roots decreased significantly; B uptook and accumulated severely decreased; The enzymatic activity of scavenging reactive oxygen species, including CAT and APX in rape seedling leaves decreased, and the endogenous reactive oxygen substances (GSH) in leaves were significantly reduced, while hydrogen peroxide and malondialdehyde increased significantly. The B-treated (0μmol/L) plants supplemented with10μmol/L Se showed increased shoot and root dry weight; CAT, POD and APX activities improved; GSH and ASA contents increased, while the accumulation of hydrogen peroxide and the increase of membrane lipid product malondialdehyde were effectively reduced. It was suggested that an appropriate Se can increase reactive oxygen metabolism of rapeseed and reduce the accumulation of reactive oxygen, thereby significantly decreasing the impact of deficiency B on rapeseed growth and improving the adaptability of rape seedlings to B deficiency.3. B and Se interaction significantly effects of the B and Se content and accumulation of rape seedlings. Under soil culture condition, application of B significantly increased the content of B content and accumulation of rape seedlings, and it beneficial to root B translocation to shoot; Shoot Se content and accumulation increased, but root Se content and accumulation decreased with application of B. Application of Se significantly decreased the content of B content and accumulation of rape seedlings, and it inhibition of root B translocation to shoot; Shoot and root Se content and accumulation increased with application of Se.4. Effects of the nutrient content of rape seedlings by B and Se interaction. Under soil culture condition, application of B significantly increased the content of shoot Fe, Mn and root N, Ca, Fe, Mn, but the content of shoot Zn, Cu, Mg, Ca, K, P and root Zn, Cu, Mg, K, P decreased. Application of Se significantly increased the content of shoot Fe, Mn and root Ca, Mg, Fe, but the content of shoot N, P, Ca, Mg, Zn and root N, P, K, Cu, Zn.