Effects Of Calcium On Physiological Characteristics Of Calligonum Mongolicum Turcz. Under Salt Stress

Different concentrations of NaCl caused different damages to the plants,and calcium salts could relieve the stress caused by Na Cl to some extent.In order to explore the effects of different types of exogenous calcium salts and the optimal combination of Na Cl and calcium under the same salt stress,the desert plant of Calligonum mongolicum Turcz.potted in plastic was used to the research material.The experimental design and profess are as follows:?1?control?CK?:not adding any Na Cl or calcium;?2?NaCl stress concentrations:50,100,200,300 mM;?3?interaction between NaCl?0,100,200,300 mM?and Ca?NO₃?₂ concentrations?5,10,15,20 mM?;?4?interaction between Na Cl?0,100,200,300 mM?and CaCl₂ concentrations?5,10,15,20 mM?.By measuring the changes of various characteristics in the assimilation branches of C.mongolicum Turcz.under the above processing conditions,the correlation degree between physiological indexes and above-ground biomass was analyzed using the grey correlation analysis method.The mechanism of salt resistance and the alleviating effect of calcium on Na Cl of C.mongolicum Turcz.were discussed.The main results are as follows:?1?The chlorophyll content and the net photosynthetic rate?P_n?of the assimilating shoots of the C.mongolicum Turcz.were increased with a little of NaCl?50 mM?,indicating that a little NaCl could promote the growth of plants;The malondialdehyde?MDA?,proline?pro?,and soluble proteins content were significantly increased and the soluble sugar,chlorophyll a,chlorophyll b,total chlorophyll,and P_n were significantly decreased at high concentrations of NaCl?300 mM?.The decrease of photosynthetic of C.mongolicum Turcz.caused by salt stress is due to the decrease of carboxylation.?2?When the calcium salt was treated alone,the physiological characteristics MDA,pro,soluble sugar in the assimilation shoots of C.mongolicum Turcz.were increased compared to CK,and the P_n was reduced to some degrees.It was found that the calcium salt alone also caused stress to the plants when treated separately.?3?Adding Ca?NO₃?₂ under NaCl stress had a significant interaction with the physiological parameters in plants.When NaCl interacts with Ca?NO₃?₂,it could increase the content of pro,soluble protein and soluble sugar in the assimilating shoots of C.mongolicum Turcz.and reduce the content of MDA.The effect of different calcium salts on chlorophyll was mainly reflected in chlorophyll A.?4?When NaCl were 100 and 200 mM,it can be seen from the MDA,pro,Pn,and soluble sugar content that adding 10 and 20 mM Ca?NO₃?₂ had the best mitigation effect.?5?Under low concentration of NaCl stress?100 mM?,low concentration of Ca²⁺had the better relieves,and high concentration of Ca²⁺would aggravate the stress;In the middle and high concentration of NaCl,the opposite was true.Under 200 and 300 mM NaCl treatments,adding the same concentration of Ca?NO₃?₂ and CaCl₂,the mitigation effect of Ca?NO₃?₂ was better than Ca Cl₂.?6?The grey relational degree analysis method showed that the correlation degree between physiological indexes and above-ground biomass as follow:intercellular CO₂ concentration>transpiration rate>net photosynthetic rate>stomatal conductance>chlorophyll A/B>pro>solubility Protein>MDA>soluble sugar>chlorophyll A>Total chlorophyll>chlorophyll B.From the above,it can be concluded that a little of NaCl?50 mM?could promote the growth of plants.Under the condition of salt stress,the gray correlation analysis showed that the index of photosynthetic parameters were significantly correlated with above-ground biomass,and the high concentration of NaCl affected the growth of C.mongolicum Turcz.and the addition of exogenous calcium salt could relieve the damage to plants caused by Na Cl stress.Under the low NaCl stress,the lower concentration of calcium salt had better remission effect,and at higher NaCl concentration,the mitigation effect of Ca?NO₃?₂ was better than CaCl₂.