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Chilling stress is a world natural disaster,has become a question to endanger farming production.Maize is an important crop,to be easily affected by low temperature. Commonly the daily average temperature is to be stabilized over 10℃,while would affected plant growth if it’s below 10℃,the time of low temperature last over longer, would causer maize seed to germinating badness,or seeding growing lowly,dying back even death.Salicylic acid(SA) belongs to a group of henolics widely distributed in plants and is now considered an hormone-like substance,which plays an important role in the regulation of plant growth and development.In recent years it has received particular attention to be a signal molecular in acquired resistance to pathogens in several species.Although the focus has been on the role of SA on biotic stresses,recently several studies also supported a major role of SA in modulating the plants response to several abiotic stresses,such as inducing resistance of plants to salt,drought,chilling and heat et al.Gibberellic acid(GA) is a highly efficient plant growth-stimulating hormone,can promote cell elongation,increased plant height,can promote genetic dwarfing the growth of plants,as well as to increase the germination rate.In the conditions of low temperature, drought,low light or short day et al,the effects of it is more significant.However,in the chilling stresses salicylic acid(SA) and gibberellic acid(GA) mixture("SG") on the maize seedlings of the system has not been reported.Based on existent research,I treat maize seedlings with different concentrations of "SG".The test simulates low temperature in early spring when inseminating seed on farm, adopt burgeon and growth test in low temperature and seed sopping test,moreover it open out change rule of physical index burgeon in low temperature in the angle of physiological biochemical and review the applicative effect on farm and also supply,theory for practice production application.The results of the test indicate:1.During chilling stress,the treatment of maize seedlings with "SG" can enhance germination energy,germination rate,germination index and vigor index.It can make the maize seedlings grow and develop fast.2.The treatment of maize seedlings with "SG" can optimize the measures of physiology and biochemistry:increase chilling resistance of maize seedling by reducing the penetrating of membrane and protecting the stability of membrane system;increase the chlorophy content,decrease stomatal conductivity and intercellular content,and increase net photosynthetic rate,it indicates that "SG" treatment can increase chilling resistance of maize seedling by improve photosynthesis;increase chilling resistance of maize seedling thorough osmoregulation by increasing the content of proline,soluble sugar;the scanning electron microscope photograph show that the structure of stroma lamellae is clear and the structure of grana lamellae is kilter;improve antioxidant enzymes activities of SOD,POD and CAT to decrease memebrane lipid peroxidation,and improve the resistance during chilling stress;there is positive or negative correlation significantly between net photosynthetic rate,stomatal conductivity, chlorophy content,intercellular content,MDA content,electrolytes leakage, soluble sugar content et al.3.The treatment of maize seedlings with "SG" can make the length of root growth fast,inhibit the number of fibrous root,significantly increased the volume of maize seedling roots,and the roots of maize seedlings of the vitality improve greatly,so that it can enhance the resistance of chilling stress significantly.4.During chilling stress,the treatment of maize seedlings with "SG" can obvious effect the morphological index of maize,indicating that significant increase in seedling height,leaf area increased,stem diameter increased.But this effect is significant to the pre-birth,no significant effect to the latter.5.The treatment of maize seedlings with "SG" can increase the production of maize in some degree,but not as good as its effect on physiological index and root vitality.
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