The Influence Of Different Nitrogen,Phosphorus,Potassium And Calcium Levels On Salt Tolerance Of Elaeagnus Angustifolia L.

Elaeagnus angustifolia L.seedlings was supplied with different nitrogen concentration,phosphorus concentration,potassium concentration and calcium concentration to study their growth and physiological characteristics under salt stress?100 mmol·L^-11 NaCl?planted in plastic pots rinsed river sand in order to confirm appropriate nitrogen,phosphorus and potassium levels in salt stress,and to provide theoretical guidance for reasonable application of fertilizer in production.The results were as follows:1.The effect of different nitrogen concentration on salt tolerance of E.angustifolia seedlings.Under NaCl treatment,the growth of E.angustifolia seedlings significantly decreased and Na⁺and Cl^-content of roots and leaves significantly increased while K⁺and NO₃^-content of roots and leaves significantly decreased.With the increasing of nitrogen concentration,the growth indicators?plant height,dry weight,fresh weight,chlorophyll content?and photosynthetic parameter?net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs??of E.angustifolia seedlings increased while intercellular carbon dioxide concentration decreased.The contents of Na⁺and Cl^-in roots and leaves decreased firstly and then increased,while the contents of K⁺increased first and then decreased.Under 0 mmol·L^-11 and 100mmol·L^-11 NaCl treatment,compared with 1 mmol·L^-11 nitrogen treatment,the treatment with 2 mmol·L^-1,5 mmol·L^-1,10 mmol·L^-11 and 15 mmol·L^-11 nitrogen significantly promoted the growth,decreased the content of Na⁺and Cl^-in roots and leaves,increased the content of K⁺in roots and leaves.The results showed that increasing nitrogen concentration moderately can alleviate the damage caused by salt stress to E.angustifolia seedlings.2.The effect of different phosphorus levels on salt tolerance of E.angustifolia seedlings.Under either salt treatment or non-salt treatment,with the increasing of phosphorus concentration,the growth of E.angustifolia seedlings present a trend of increasing first and then decreasing.The growth indicators?plant height,dry weight,fresh weight,chlorophyll content?and photosynthetic parameter?net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs??of E.angustifolia seedlings increased first and then decreased.Intercellular carbon dioxide concentration decreased first and then increased.The contents of Na⁺and Cl^-in roots and leaves decreased firstly and then increased,while the contents of K⁺and NO₃^-increased firstly and then decreased.The content of PO₄^3-increased continuously.Without NaCl treatment,the optimum phosphorous concentration for E.angustifolia seedlings are0.6 mmol·L^-11 and 1 mmol·L^-11 and with 100 mmol·L^-11 NaCl treatment,the optimum phosphorous concentration for E.angustifolia seedlings is 0.6 mmol·L^-1.3.The effect of different potassium levels on salt tolerance of E.angustifolia seedlings.100 mmol·L^-11 NaCl treatment significantly inhibited the growth of E.angustifolia seedlings and Na⁺and Cl^-contents in roots and leaves significantly increased while NO₃^-content in roots and leaves significantly decreased,K⁺content in roots and leaves didn't changed.Whether the salt treatment or non-salt treatment,with the increase of potassium concentration,the growth of E.angustifolia seedlilngs showed a trend of first increasing and then decreasing.The growth indicators?plant height,dry weight,fresh weight,chlorophyll content?and photosynthetic parameter?net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs??of E.angustifolia seedlilngs increased first and then decreased.Intercellular carbon dioxide concentration decreased first and then increased.The contents of Na⁺and Cl^-in roots and leaves decreased first and then increased,while the NO₃^-content increased first and then decreased.The content of K⁺increased continuously.Under the treatments of2 mmol·L^-11 and 5 mmol·L^-11 potassium,the seedlings grew the best.The results showed that the optimum concentration of potassium was 2 mmol·L^-11 and 5 mmol·L^-1under salt stress.4.The effect of different calcium levels on salt tolerance of E.angustifolia seedlings.The growth of E.angustifolia seedlings was significantly inhibited under 100mmol·L^-11 NaCl.With the increase of calcium concentration,the growth?plant height,dry weight,fresh weight,chlorophyll content?and photosynthetic parameter?net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs??and chlorophyll content of E.angustifolia seedlings increased at first and then decreased.The trend of intercellular carbon dioxide concentration is the opposite.The content of Na⁺and Cl^-in roots and leaves decreased,the content of K⁺and NO₃^-increased and the content of Ca²⁺increased continuously.Under the treatment of 0 mmol·L^-11 and100 mmol·L^-11 NaCl,compared with the other treatments,2 mmol·L^-11 and 5 mmol·L^-1calcium treatment significantly increased the growth indicators?plant height,dry weight,fresh weight,chlorophyll content?and photosynthetic parameter?net photosynthetic rate?Pn?transpiration rate,?Tr?,stomatal conductance?Gs??and decreased the intercellular carbon dioxide concentration.Na⁺and Cl^-content was significantly reduced,K⁺and NO₃^-content was significantly increased.The results showed that the appropriate concentration of calcium could reduce the effect of salt stress on E.angustifolia seedlings.The optimum concentration of calcium for E.angustifolia seedlings was 2 mmol·L^-11 and 5 mmol·L^-1.5.A mechanical mixing experiment of N,P,K and CaThe growth of E.angustifolia seedlings was significantly inhibited under 100mmol·L^-11 NaCl and the older leaves fell off.In the absence of salt treatment,1/4B treatment group has the lowest plant height,the lowest fresh weight and dry weight of shoots and roots,and the lowest and photosynthetic parameter?net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs??,the highest intercellular carbon dioxide concentration,while Na⁺and K⁺contents in roots and leaves did not change significantly.Under salt stress,plant hight,fresh weight and dry weighet of shoots and roots,chlorophyll content and photosynthetic parameter of E.angustifolia seedlings was the lowest and Na⁺contents in roots and leaves was the hightest and K⁺contents in roots and leaves was the lowest.Whether the salt treatment or non-salt treatment conditions,there is no significant difference between A and B.Compared with the 1/4B group,E.angustifolia seedlings grows better with the increase of mechanical mixed solution.6.Orthogonal experiment of N,P,K,and CaOur previous studies found the optimal nitrogen concentration under salt stress is2 mmol·L^-1,the optimal phosphorus concentration was 0.6 mmol·L^-1,the optimum concentration of potassium was 2 mmol·L^-1,the optimum calcium concentration was2 mmol·L^-1,on the basis of this,four factors and three levels orthogonal experiment was carried out to study the best ratio of the four elements?N,P,K,and Ca?for the E.angustifolia seedlings under salt and non-salt.The results show that plant height,dry weight,fresh weight,chlorophyll content of E.angustifolia seedlings under A3B1C3D2,A3B2C1D3 and A2B2C3D1 were the highest without salt treatment,while were A3B1C3D2 and A3B2C1D3 under salt stress.