Study Of Physiological Mechanism Of Alfalfa In Salt Tolerance

In this study, hydroponic culture has been adopted as the experimental approach, and victoria alfalfa and Zhongmu No.1 alfalfa have been selected as the experimental materials, which have been focused on two experiments including exogenous ABA under sodium chloride tolerance and four K⁺ gradient under sodium chloride tolerance. These two experiments will conduct a research on the growth of the plants, changes of ion inside plants and conditions of osmoregulation in order to fully understand and grasp the mechanism of salt tolerance in plant physiology and provide a theoretical basis for the cultivation of salt tolerant mechanism. It also plays a very important role in improving capacity of salt tolerance and achieve the effective development and utilization of saline-alkali soil. The results show that:1. Fresh weight and dry weight of root, stem, leaf of the two alfalfas were significantly decreased in sodium chloride tolerance . ABA was added to reduce the phenomenon of growth inhibition of two alfalfas, and the phenomenon was more evident with the adding of the concentration 10μmol / L. In different organs accumulated a large amount of proline in sodium chloride tolerance, distributing in leaf> stem> root, and exogenous ABA significantly increased the proline content in various organs. And Victoria alfalfa, proline content was significantly higher than in the clover on the Zhongmu No.1 alfalfa. Under sodium chloride tolerance, if added ABA, enhanced Na⁺ accumulation in roots, stems and promoted the transportation of K⁺ to the stems and leaves. Under sodium chloride tolerance, K⁺, P,Ca²⁺, Fe³⁺, Mn²⁺, Zn²⁺, Mo etc. were reduced, add the ABA can ease the decreasing tendency; but Under sodium chloride tolerance, Na⁺ and Mg²⁺ content were increased, adding ABA can ease the increasing trend; the Cu²⁺ content changed little in sodium chloride tolerance, the ABA accession has no effect. 2. The fresh and dry weight of the two alfalfas'roots, stems and leaves increased instead in sodium chloride and potassium chloride tolerance. Roots and leaves had a large margin of increase than that of the stem; when K⁺ concentration was low, fresh weight and dry weight of the two alfalfas had decreased, but decreased to a lesser extent, indicating that lowering K⁺ concentration could affect the growth of plants; when the K⁺ concentration was high, plant growth was inhibited by K⁺ stress, and fresh weight and dry weight of the two alfalfas decreased significantly. Content of K⁺ and P were significantly decreased in sodium chloride tolerance, but the downward trend in the case of hypokalemia and hyperkalemia was greater. When potassium concentration was in the right conditions, K⁺ and P content decreased less significantly. Under sodium chloride and potassium chloride tolerance, Ca²⁺ content increased in the roots and stems of two alfalfas, but the Ca²⁺ content in leaves decreased significantly. Mg²⁺content increased when K⁺ concentration was appropriate and high, but in the case of low potassium ion concentrations, it decreased. The results also showed that, NaCl, and appropriate K⁺ stress, Fe³⁺ content did not change, but the stress of high K⁺, Fe³⁺ content was significantly reduced. in sodium chloride and potassium chloride tolerance., Mn²⁺, Zn²⁺ , Cu²⁺, B, Mo and other elements of content were significantly reduced. However, when potassium concentration was moderate, reducing trend would be minimized.