Effect Of Salt Stress On Photosynthetic And Physiological Characteristics Of 5 Kinds Of Garden Shrubs In Southern China

The Southern China area has a long coastline,and the coastal saline alkali land has become a major problem facing the landscape of this area.The varieties of coastal greening plants with good salt tolerance should also be paid attention to by the theoretical research of garden plants and the construction of urban greening.This choice of 5 kinds of common garden shrubs(Thevetia peruviana ?Pittosporum tobira?Duranta repens?Hibiscus rosa-sinensis?Lantana montevidensis)in Southern China coastal area as the research material,in the planting soil configuration adding NaCl reagent of different gradient(including the amount of salt is 50mmol/kg,100mmol/kg,200mmol/kg and 300mmol/kg)and control group(salt0mmol/kg),artificial simulation of coastal area soil salt stress environment,are measured at different stress time points(20d and 40d)on the photosynthetic efficiency and fluorescence index(20d and 40d)numerical physiological and biochemical index,comparative analysis of plant salt tolerance,and comprehensive evaluation.According to the test results,we know that:1.Under the same concentration of salt treatment,the Pn of 5 plants gradually decreased with the extension of treatment time.Under the same salt stress,the Pn of 5plants gradually decreased with the increasing of salt concentration.Under salt stress20 d,5 species Gs decreased with the increasing of salt density,stress 40 d,the Gs of Duranta repens first decreased and then increase with increasing salt consistency,others decreased with the increasing of salt density;under salt stress,5 species of Gs decreased gradually with the prolongation of salt stress.At the same time,the Ci of Duranta repens decreased first and then increased with increasing salt density,others decreases with the increasing of salt consistency;in the same salt treatment,the Ci of Duranta repens first decreases and then increased with the increasing of stress time,others decreases with the extending of time.At salt stress 20 d,the Tr of 5 species decreased with the increasing of salt density.Besides,at stress 40 d,the Tr of Duranta repens with increasing salt concentration decreased first and then increased in the same concentration,others decreases with the increasing of salt density;with theincreasing of salt stress,the Tr of Duranta repens first decreased and then increased,others gradually reduced.2.Under the same stress time,the Y(II)of 5 plants gradually decreased with the increasing of salt concentration.With the prolonging of stress time,the Y(II)of all 5plants decreased.Under salt stress 20 d,5 species of NPQ concentration was gradually reduced with the increasing of salt,the NPQ of Duranta repens with increasing salt density but decreased,others with increasing salt concentration decreased under the stress of 40 d.Under the same stress time,the Y(NO)of 5 plants increased gradually with the increasing of salt treatment consistence.With the extending of stress time,the Y(NO)of all 5 plants increased then the past time.3.Under the same stress time,the chlorophyll content of 5 plants decreased with the increasing of salt treatment concentration.With the extension of salt stress,the chlorophyll content of all 5 plants decreased compared with that before.Under the same stress time,the MDA content of 5 plants increased gradually with the increasing of salt treatment concentration.With the elongation of salt stress time,the MDA content of all 5 plants increased at the same time.Under the same stress time,the relative conductivity of 5 plants increased with the increasing of salt concentration.With the elongation of salt stress,the relative conductivity of 5 plants increased at the same time.Under the same stress time,the proline content of 5 plants increased with the increasing of salt treatment concentration.With the elongation of salt stress,the proline content of 5 plants increased at all times.4.Using membership function analysis method,5 kinds of plants at the highest salt concentration and the longest time under 11 kinds of stress with different salt tolerance index comprehensive evaluation analysis,the level of salt tolerance of 5species as follows: Thevetia peruviana> Pittosporum tobira> Lantana montevidensis > Hibiscus rosa-sinensis> Duranta repens.