Identification Of Salt Tolerance In Transgenic Alfalfa Of The RstB

The transgenic alfalfa is high quality resource of forage, to study its salt tolerance is the important base for its introduction, breeding and extending.The integrated salt tolerance of two species of transgenic alfalfa and Baoding alfalfa, which were tested under 0%, 0.3%, 0.5% and 0.7% salt of NaCl concentration by measuring the agronomic traits, physiological and biochemical indexes such as germination rate and procreate time, speed of growth, mortality, cell membrane permeability, chlorophyll content, free proline content, MDA content and soluble sugar content, lycine content and activity of protective enzyme of its plants. The results as follows:1. Most agronomic traits, physiological and biochemical indexes of alfalfa have changed greatly under salt stress, and the amount of variety is different in terms of materials and indexes. The pertinence between different indexes from the same species and the NaCl concentration is dissimilar as well as the same index from different species and the NaCl concentration. The result will be not completely consistent when selecting different indexes to appraise the salt-toletance of alfalfa. So, it is reasonable to estimate the alfalfa, salt tolerance by synthetizing many different indexes instead of using a single index.2. NaCl stress has obviously restrained the germination of alfalfa which were adopted in the test, made the germination rate of its seeds evidently reduction, especially Baoding alfalfa. when the NaCl concentration is equal to or above 0.9%, the germination rate of Baoding decreased 19.3% so as to almost could not germinate under1.0% NaCl stress. Then, the germination rate of transgenic alfalfa is 17.3% under 1.1% NaCl stress. Therefore,it can be concluded that the response of transgenic alfalfa seeds is less sensitive than Baoding alfalfa to NaCl stress.3.The agronomic traits ,physiological and biochemical indexes which were screened based on the results of analysis for comprehensive evaluation on salt tolerance of alfalfa are germination rate root length, speed of growth, mortality, soluble sugar content, lycine content, chlorophyll content and cell membrane permeability. Stem/leaves, Dry/fresh, free proline and MDA content, active of SOD, POD and CAT can be used as the referenced indexes to estimate the salt tolerance of alfalfa.4. According to the results of integrated analysis, the conclusion is that the transgenic alfalfa is superior to Baoding alfalfa in salt tolerance .