Analysis Of Different Salt Tolerance Of Six Species In Genus Kalidium

Salt tolerance is a complex trait that is thought to have multiple origins in plants,and during the evolution,various halophytes readapt to make them live in high salinity environment.Kalidium?Chenopodiaceae?is a genus of succulent euhalophytes with six species has a certain ability to adapt to saline-alkali soil and desert areas in Northwest China.On the basis of full field survey,soil samples?0-100 cm?from the different areas where six species of Kalidium distributed were collected.pH value,total salt contents,and the concentrations of Na⁺,K⁺,Ca²⁺,Mg²⁺,CO₃^2-,Cl^-,HCO₃^-,SO₄^2-from the soil samples were analyzed.Seeds germination and the growth of roots among six species were tested under different concentrations of NaCl?0-500 mM?and Na₂SO₄?0-250 mM?.Then the germination percentage and recovery germination percentage,and the growth percentage of roots under different concentrations were calculated.The relative physiological indexes of four months old seedlings were determined after treatments with different contents of NaCl?300 mM,400 mM,500mM?for 30 days.The results are as following:1)pH value mainly ranges from 8.5-10.5;The total salt concentrations of the soil where K.cuspidatum,K.gracile,K.sinicum,K.foliatum located can be as high as 72.37 g/kg,74.69 g/kg,76.50 g/kg,66.46 g/kg,and the maximum of K.caspicum and K.schrenkianum only are 51.48g/kg,12.98 g/kg,respectively.Na⁺is the most abundant cation in all soil samples,and has a very significant positive correlation with total salt contents at all depths?except 20-40 cm?.Cl^-with a higher concentration of 10.62 g/kg in K.cuspidatum distributed area,and the content of SO₄^2-is as high as 11.78 g/kg in K.capsicum distributed areas;2)The germination percentages of six species are negatively correlated with the increase concentration of NaCl and Na₂SO₄,the germination percentage still can reach 45%in K.cuspidatum at a higher concentration of NaCl?200 mM?.While in Na₂SO₄,the maximum of germination percentage is 55%?150 mM?in K.capsicum,the growth percentage of radicle in K.cuspidatum is the highest as 49.93%in 300 mM NaCl;and in 150 mM Na₂SO₄,the maximum of K.capsicum is 21.23%followed after K.cuspidatum and K.foliatum;3)After treatment with 300 mM NaCl,the growth of K.sinicum is inhibited,and the plant height is decreased by 22.57%than the control;water content is only about 47.73%which below50%;and the activities of three antioxidant enzymes?SOD,CAT,POD?are also decreased;While the proline content was also highest as 361.62?g/g FW.When the concentration is high as400 mM,the activities of SOD,CAT and POD in the K.capsicum are 144.49 U/g FW,163.66nmol/min/g FW,14933.74 U/g FW,respectively.Under the extreme concentration?500 mM?,However,K.cuspidatum,K.foliatum,K.gracile are still able to survive,and the proline contents in each species reached the maximum of 412.17?g/g FW,248.77?g/g FW,172.98?g/g FW,respectively.The activities of SOD and CAT in K.foliatum?K.gracile can also be the highest.While in K.cuspidatum the total chlorophyll content is 0.26 mg/g FW,which is higher than others.In summy,the total salt contents of soil,Na⁺level in the six Kalidium species is positively related to the increasing concentration of NaCl on the whole,and so as well the proline and malondialdehyde.However,there is no significant difference in glycine betaine.These findings suggest that adaptation to topsoil salinity in early stages is a major determinant of the six species‘geographical distributions.However,relative proportions of the ions are also apparently important as K.cuspidatum and K.caspicum occupy areas where the major anions are Cl^-and SO₄^2-,respectively.The differences in salt content,pH value and ion concentration of different areas can make one obvious choice to the spectrum distribution of Kalidium;and the different salt tolerance of six species in genus Kalidium are mainly determined by the salt in their habitat.