Response Of Jerusalem Artichoke(Helianthus Tuberosus)to Soil Stress And Exogenous Nitrogen Regulation Effects

With the increasing world population, industrialization development and human factors, ecological environment become worse. Meanwhile, soil of salinization and arid are becoming prominent. It’s not only hindered the development of agriculture and animal husbandry, but also restricts the construction of ecological environments. Jerusalem artichoke (Helianthus tuberosus) is a kind of perennial and herbaceous plant, which belongs to the sunflower plant group of Asteraceae. In view of nitrogen plays an important role in regulating plant resistance, we analyzed the responses of Jerusalem artichoke to soil stress and regulation effects by different forms nitrogen, and provided theoretical basis for resistance physiology and improved Jerusalem artichoke resistance by nitrogen fertilizer in practice. The main results and conclusions were as follows:(1) We mixed four main salts NaCl, Na2SO4, Na2CO3, NaHCO3 according to different molar ratio to simulate complex salt condition in Songneng grassland. The results showed that the growth and photosynthesis of Jerusalem artichoke seedlings were inhibited with increasing ratio of alkaline and stress concentration. A marked increase in Na+ contents, and the highest Na+ under 60 mM stress treatment of which contained highest alkaline component, the change of K+ content was not obviously, but Na+/K+ increased. A large of Cl" was accumulated while Na+ increased under saline stress. When alkaline components increased, the Cl" uptake was inhibited, but oxalic acid, malic acid and citric acid were increased dramatically. Higher salinity and pH interactions has the greatest effects on the growth and physiological metabolism of Jerusalem artichoke, and the inhibition is much greater than only high salt or high pH stress group.(2) Jerusalem artichoke seedlings were stressed by NaCl and NaHCO3. Both growth and photosynthesis were restrained under saline and alkaline stresses, but the inhibitory effects of alkaline stress were much stronger. Na+ content increased under saline and alkaline stresses, especially the highest Na+ content in roots of Jerusalem artichoke seedlings, and the K+ didn’t change under saline stress, but decreased significantly under alkaline stress; Mg2+ contents in root were decreased under both stresses, but on the contrary to the change trend of that in leaves, and a substantial accumulation of Mg2+ in the leaves under higher alkaline stress. Cl-was accumulated significantly to balance excessive cation under saline stress, and the change of organic acid is not obvious under saline stress. Under alkaline stress, organic acid accumulated greatly, and acetic acid has the largest increasing extent. A large accumulation of Cl- and organic acid were the main physiological mechanisms differences between Jerusalem artichoke adapt to saline stress and alkaline stress.(3) Jerusalem artichoke resistant to saline and alkaline stresses was influenced by different form nitrogen. Under both stresses, the photosynthetic capacity and dry weight of root, stem and leaf were all increased by exogenous nitrogen, especially nitrate. The nitrogen effect was stronger under saline stress than that under alkaline stress. The Na+ and Cl" contents of Jerusalem artichoke seedlings were decreased by exogenous nitrate addition under both stresses, the improvement of K+、Ca2+ and NO3- content. In addition, the accumulations of organic acid were promoted by exogenous nitrate under alkaline stress to balance homestasis and osmotic balance. Antioxidant enzymes were induced by exogenous nitrogen, SOD and POD enzyme activity were the strongest when NH4+ applied.(4) Compared with ammonium nitrogen and ammonium nitrate mixed nitrogen, nitrate nitrogen significantly improved the growth and photosynthetic parameters of Jerusalem artichoke seedlings in short-term drought stress. Applying nitrate reduced the inhibitory effect of drought stress, the inhibition effect of drought was exacerbated by ammonium. Nitrate nitrogen significantly increased the content of K+ and Ca2+, especially in roots. Under drought stress, proline content increased signigicantly and the strongest antioxidant enzyme activity by exogenous ammonium nitrogen. It shows that accumulation of proline is a passive response to stress in Jerusalem artichoke. Water and nitrogen addition after the long drought, effects of different nitrogen form on Jerusalem artichoke recovering ability and short-term drought showed the similar results, the nitrate nitrogen made the recovery ability of the largest increase in Jerusalem artichoke, it shows that intake of nitrate nitrogen plays an important role on adaption to drought stress and the recovery after drought stress in Jerusalem artichoke.