| In recent years,extreme high temperature climate occurs frequently,and the impact of heat damage caused by high temperature stress on garden plants is becoming more and more serious.The high temperature stress caused by the increase of greenhouse gases has become one of the important environmental stresses that hinder the distribution,production and growth of garden plants.A large number of studies have shown that salicylic acid(SA)and exogenous calcium(Ca2+)play an important role in plant resistance to abiotic stress.In order to explore the mitigation effect of Ca2+ and SA on high temperature stress of Acer truncatum,4-year-old Acer truncatum was used in this experiment to investigate the effects of Ca2+ and SA on the heat tolerance of Acer truncatum under different concentrations,and to alleviate the height of Acer truncatum The optimum concentration of temperature stress.The main research contents and results are as follows:(1)With the increase of high temperature stress time,the growth of plant height,ground diameter and crown width of Acer truncatum was significantly inhibited,and the heat injury index was significantly increased.0.5 mmol·L-1SA was the best,followed by 0.1 mmol·L-1SA and 20 mmol·L-1Ca Cl2,and 50 mmol·L-1Ca Cl2 had inhibitory effect.(2)The results showed that the electrolyte permeability,soluble protein,soluble sugar and malondialdehyde decreased with the duration of high temperature.With the duration of high temperature,the electrolyte permeability,soluble protein,soluble sugar and malondialdehyde of Acer truncatum decreased with the extension of time.Ca2+ and SA also effectively reduced the osmotic regulation of Acer truncatum under high temperature stress to varying degrees,with a value of 0.5 mmol·L-1SA treatment had the best effect,significantly reduced the electrolyte permeability,soluble protein content,soluble sugar content and malondialdehyde,thus enhancing the osmoregulation ability of Acer truncatum,and finally alleviated the osmotic adjustment injury of Acer truncatum under high temperature stress.(3)Under high temperature stress,total chlorophyll content,net photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpiration rate decreased continuously,among which SA at 0.5 mmol·L-1 significantly slowed down the decline trend of photosynthetic substances;0.5 mmol·L-1 SA and 20 mmol·L-1 Ca Cl2 followed,and 50mmol·L-1 Ca Cl2 decreased the most,which inhibited the photosynthetic pigments of Acer truncatum under high temperature stress.(4)In addition to 50 mmol·L-1 Ca Cl2,0.1 mmol·L-1 SA,0.5 mmol·L-1 SA and 20mmol·L-1 Ca Cl2 could effectively reduce the production of antioxidant enzymes and alleviate the effect of high temperature stress on antioxidant enzymes,among which 0.5 mmol·L-1 SAhad the most significant effect.In conclusion,both Ca2+ and SA could alleviate the high-temperature heat damage of Acer truncatum,but the treatment concentration had a greater impact on the mitigation effect.The results showed that SA had the best effect at the concentration of 0.5 mmol·L-1,and the mitigation effect of Ca2+ was slightly weaker than that of SA.This study can provide theoretical basis and guidance for improving the adaptability of landscape tree species to high temperature stress.Exogenous calcium and salicylic acid have different degrees of relief under high temperature stress,Under the concentration of 0.5 mmol·L-1 SA,treatment had the best mitigation degree,which could significantly reduce the heat injury parameters and electrolyte permeability,improve the growth index,reduce the content of soluble protein,soluble sugar and malondialdehyde,and improve the photosynthetic efficiency and chlorophyll content,so as to alleviate the stress caused by high temperature and improve the heat resistance of Acer truncatum,which provided theoretical basis for improving the effect of high temperature stress on Acer truncatum. |
PDF Full Text Request