| In recent years, the facility agriculture in a very rapid pace in China around the development of China's agriculture has become the most dynamic new industries, have made significant economic, social and ecological benefits. Cultivation is characterized by use of artificial measures to change the local ecological environment, and make full use of solar energy and geothermal energy, to improve the yield and quality of vegetables play an important role. However, due to environmental facilities by special greenhouse environment and man-made water and fertilizer management measures the impact of environmental conditions in confined and no natural rainfall, evaporation, the facilities at the same time under the conditions of the excessive use of fertilizers, the soil surface throughout the year in a plot of salt in the soil and Salinization of the phenomenon, caused production to a lot of impact.5 - amino acid (5 - aminolevulinicacid, ALA) is that all organisms porphyrins including chlorophyll, heme iron, cobalt-amine, such as photosensitive-biological synthesis of a key precursor, it is not simply a Biological metabolic intermediate product, it also involved in the regulation of plant growth and development process, a plant hormone similar to the physiological activity in the agricultural production on the potential applications have received increasing attention. High concentration of herbicides can be used as farmland, low concentration can regulate plant growth and development, and promote crop production, increase resistance, and so on. In recent years studies have shown that, ALA in improving the plant anti-cold, salt tolerance, tolerance of poor light on a high prospect, but the domestic ALA on the salt tolerance of tomato plants affected very little research, ALA to improve salt-tolerant plant And the mechanism is not yet very clear, for further study.Treated with exogenous ALA and SA under two concentrations of (150mmol·L-1, 250mmol·L-1) NaCl stress. Probed into physiological and biochemical mechanism of salt toletance and the optimal concentration of tomato treated by exogenous ALA under salt stress. The main results were showed as followed: 1,Effect of exogenous ALA and SA on tomato harmed by salt stress: ALA and SA alleviated the inhibition of tomato growth under saltstress(150,250mmol/L NaCl). However, ALA was the best one, The results from physiological and biochemical indexes showed that the exogenous ALA were very significantly higher than contrast, chlorophyll content, POD and Pro content of leaf were much improved by 58.11% ,125.53%and 120.36%.,the difference is clear. It could induce salt resistance, salt tolerance and decrease alleviate damage degree of salt of tomato plant.2.NaCl stress seriously inhibit the growth, height, stem diameter and leaf area of tomato plants, the tomato leaf chlorophyll content significantly decreased. The longer time, the more serious damage. The root activity raised firstly and then decreased under 150 mmol ? L-1NaCl stress, while under 250 mmol ? L-1NaCl stress for the performance of continuous decline, and affected the life-sustaining activities tomato water supply. Compared with the salt treatment, the different concentrations of exogenous ALA can improve the plant height, stem diameter ,leaf area, root activity and slowed down chlorophyll content of the tomato reduced rate. The adopt consistence is 0.3g/m2 , but when the consistence of salicylic acid raise too high the effect of relieve is not obvious.3. Under NaCl stress, a serious impact on the activity of tomato plants oxygen system, the promotion of the lipid peroxidation. The peroxidase (POD) increased after the first lower, catalase (CAT) and superoxide dismutase (SOD) activity declineded. The content of malondialdehyde (MDA) and membrane permeability increased. NaCl stress can stimulate the tomato active oxygen scavenging system enzyme system in the SOD, POD, such as enzyme activity, but with the extension of the time, NaCl stress intensifies, active oxygen scavenging system in the activity of decline. Exogenous ALA can reduce the accumulation of leaves MDA and membrane permeability, effectively alleviate stress caused by salt tomato plant leaf cells of lipid peroxidation. Effects of 0.3g/m2ALA, significantly increased tomato leaves POD, CAT, SOD activity, and be able to guarantee its long period of time to maintain high activity, thus reducing the content of the MDA, to maintain the stability of the film, Increase the salt tolerance of tomato.4.Under NaCl stress, the tomato plants stimulate the infiltration of regulatory function, expressed as proline, total soluble sugar and soluble protein content of the material conditions of infiltration in the early treatment significantly increased, but with the extension of time dealing with stress, the osmolyte in decline, so that tomato salt injury suffered heavier. The 0.3g/m2ALA can further improve the tomato plants osmolyte and remain the high concentration. 5.As the salt concentration increase, the fruit weight and yield per plant gradually decreased and the difference is obvious. The soluble protein, vitamin C and soluble sugar content also decline with different degrees. Compared with salt treatment, the different concentrations of exogenous ALA can increase the output of tomato, increase the fruit of soluble protein, Vc content, raising the soluble sugar content.6. From the results can be seen, the different concentrations of exogenous ALA improved the physiological and biochemical indicators. The adopt consistence is 0.3g/m2 , but when the consistence of salicylic acid raise too high the effect of relieve is not obvious. The mechanism and molecular basis are not very clear,so exogenous ALA improve the mechanism of resistance still needs further study. |
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