Study On The Physiology Response To Adaptability Of Spiraea Bumalda 'Gold Mound' Under Salt-alkaline Mixed Stresses

Spiraea bumalda'Gold mound'belonging to Spiraea L.family in Rosaceae which are perennial defoliate shrubs.It originate in America and introduced in our country in April 1990. Base on research of planting it about more than ten years,find that there are many excellent characteristics which are strong resistance to drought and barren,low temperature,high salt,diseases and pest so that it could be perfect ornaments and be applied in city gardening.Spiraea bumalda'Gold mound'was test material in the experment.According to the saltcomposition of soil in westen Hei Longjiang,Spiraea bumalda'Gold mound' was stressed with 24 kinds of mixed salts composed of NaCl,Na₂SO₄,NaHCO₃ and Na₂CO₃ at various proportions and differed in salinity and alkalinity each other.The salt composition and range of treatment liquid were similar to the actual conditions of soil.The total salt concentration range of 25～150mmol/L and pH value from7.08～10.45,the extent of Salt-alkali mixed stress under artificial controlled.Eleven strain indexes such as survival rate were determined in order to analyze the characteristics of the stresses due to the salt-alkali mixes and their main stress factors.The results showed as followed:1.Spiraea bumalda'Gold mound' at low degree stress within 25～50mmol/L salt concentration, regardless of how the pH value does change(pH:7.08～10.18),when the low pH value is the neutral salts group(A group),the salinity increases how many(25～150mmol/L),the survival percentage not affected is 100%throughout.In a word,if salt concentration was less than 75mmol/L and the pH value below 8.79.Spiraea bumalda'Gold mound' can survival.2.Under the low salinity 25～75mmol/L,Chlorophyll content of Spiraea bumalda'Gold mound' in the neutral salts group(A group) or the lower alkali group(B group) was higher than that in control.At low degree stress within 25～50mol/L salt concentration, Chlorophyll content showed an increasing tendency and decreased rapidly with the increasing of salt-alkali concentration.The low concentration of Salt-alkali can stimulate the synthesis of chlorophyll,but the effect of high degree stress of Salt-alkali was opposite.3.The electrolyte leakage rate of Spiraea bumalda'Gold mound' was not significantly increased under the low salinity(25～50 mol/L)-high alkalinity(pH:9.35～10.18)or the low alkalinity(pH:7.13)-high salinity(100～150mmol/L) stress.It showed that Spiraea bumalda'Gold mound'has a certain salt-toerance.However,with the increasing of saltalkali concentration,the electrolyte leakage rate increased rapidly,and the plasma membrane was seriously damaged.They are in good agreement with the change tendency of malonadehyde content which used as the membrane lipid peroxidation index. 4.With the increasing of salt-alkali concentration,the Na⁺ concentration and the values of Na⁺/K⁺ in roots and leaves of Spiraea bumalda'Gold mound' were increased,while the K⁺ concentration were decreased gradually.The order of Na⁺ contentration in different organs of spiraea bumalda'Gold mound' was as following:roots>leaves,and the order of K⁺ oncentration was as following:leaves>roots,The roots which prevent excessive Na⁺ from transporting to the cotyledon were the main injure tissue of Salt-alkali mixed stress.5.The proline which is soluble organic osmotica increased with the increasing of salt-alkali concentration.At the diffenert alkali stress,the soluble protein contentration was decreased with the increasing of pH value.The starch and soluble sugar contentration had no obvious change after treatment.6.There were synergetic effects of salt and alkali concentration to plant physiological properties,in another word,the alternant action between high salt concentration and high alkali concentration damaged Spiraea bumalda'Gold mound'much more severe than single salt or alkali.To sum up,Spiraea bumalda'Gold mound'has a certain Salt-alkali toerance which can be introduced and cultivated into the the low salinity-high alkalinity or the low alkalinity -high salinity area.