Effects Of Salicylic Acid On Physiological Effects Of Different Inbred Lines Of Maize Seedlings Under Low Temperature Stress

Chilling injury is an important factor to restrict the normal growth and development and yield potential of Maize.Salicylic acid(SA)is a kind of plant growth regulator,which can be absorbed by leaves,stems and flowers.SA can improve the stress resistance of plant seedlings under abiotic stress.In this experiment,The cold resistant inbred lines of maize Kr701,B125 and susceptible inbred line maize Hei 8834,Chang 7-2 were used as experimental materials.The concentration of was tested by setting 5 SA concentration gradients,as well as SA concentration screening test at room temperature(25?)and low temperature(4?).Through the research on the growth of maize seedling,photosynthetic system,osmotic system and antioxidant enzyme system,To clarify the effect of SA on Chilling Tolerance of maize seedlings,and to explore the effect and mechanism of SA onchilling tolerance of maize.In order to provide some help for the study of physiological cold resistance of maize seedlings.The main results of this study are as follows:1.Under low temperature stress and normal temperature,Based on the determination of plant height,shoot dry weight,root length,relative conductivity,relative water content,photosynthetic characteristics(chlorophyll,Fv/Fm,Pn,Ci and Gs)and protective enzyme activity(SOD,POD and MDA)of maize seedlings,the optimum concentration of SA was determined at two temperatures and the optimal concentration of SA was 50 mg/L.The effect of SA on Maize Seedlings under low temperature stress was more significant.2.Under normal temperature,SA showed a low concentration of SA(25-100 mg/L)spraying on the growth of maize seedlings,which could promote the growth of maize seedlings,however the high concentration of SA(150 mg/L)could inhibit the growth of maize seedlings.3.Under low temperature stress,SA treatment promoted the accumulation of osmotic adjustment substances in maize seedlings(Pro,soluble sugar and soluble protein),enhanced the osmotic adjustment ability of maize seedlings,to maintain relatively high leaf water content.At the same time,SA increased the antioxidant enzyme activity(SOD,POD and APX),enhanced DPPH free radical scavenging rate,increased its ability to scavenge active oxygen free radicals,the content of H2O2 and O2-production rate decreased,reduced lipid peroxidation,protected the structure of cell membrane,thereby reducing the leaf relative conductivity.SA treatment slowed chlorophyll content,net photosynthetic rate(Pn),Fv/Fo decreased and Fo increased,Reduced intercellular carbon dioxide concentration(Ci),maintained a highlevel of Fv/Fm,maintained a high photosynthetic capacity,promoted the accumulation of biomass.And25-150 mg/L SA spraying treatment can improve the cold tolerance of maize seedlings to some extent.4.SA has a protective effect on four different maize inbred lines.SA processing of cold sensitive maize varieties is stronger.The change trend of cold sensitive cultivars is relatively large.The spraying effect order is: Hei 8834 and Chang 7-2 > Kr701 and B125.In conclusion,the appropriate concentration of SA spraying treatment can promote the growth of Maize Seedlings under normal temperature conditions,at the same time to alleviate the damage caused by low temperature stress on maize inbred lines,and 50 mg/L SA treatment was the optimal concentration of the concentration range.