On The Effects Of Different NaCl Concentrations On Physiological And Biochemical Indexes Of Tomato Seeding Stage

Solarium lycopersicum is widely cultivated all over the world and is one of the indispensable vegetables in the world.Worldwidely,salt stress has become a difficult problem,which inhibits the normal growth and development of plants,even the quality and the yield.Therefore,it is of great significance to study the physiological metabolism and salt tolerance mechanism of tomato under salt stress,for cultivating salt-tolerant varieties and making rational use of saline-alkali soil resources.In this experiment,tomato variety“CM966”was used as experimental material,and a mixture of vermiculite and perlite?3:1?was used as seedling substrate,and 5 kinds of NaCl concentrations were set:0 mmol/L?CK??50 mmol/L?100 mmol/L?150mmol/L?200 mmol/L Each treatment was repeated 3 times.The nutrient?Yamazaki,Japan?was changed every 5 days for 15 days.It is to study the effects of different concentrations of NaCl stress on morphology,photosynthesis,active oxygen scavenging system and ion distribution of tomato.And the result is that:1.Salt stress inhibited the growth of tomato shoot and underground.The higher the concentration of NaCl was,the more significant the inhibition of NaCl stress was.NaCl stress can affect the stem diameter,main root length,lateral root length,root volume and root surface area.NaCl stress directly affected the root development and root configuration of tomato.The change of root configuration affected the water and nutrient absorption of the plant which ultimately affected the growth and development of the shoot part of tomato.2.The net photosynthetic rate of tomato leaves was inhibited by NaCl stress,and the decrease of photosynthetic rate was positively correlated with the concentration of NaCl,and increased with the increase of NaCl concentration.The photosynthetic indexes such as intercellular concentration of CO₂,stomatal conductance,transpiration rate,chlorophyll a,chlorophyll b and total chlorophyll in tomato leaves showed a decreasing trend.Therefore,under NaCl stress,the photosynthetic system of tomato leaves was destroyed,which inhibited the photosynthesis efficiency of tomato leaves.3.The activity of active oxygen scavenging system in tomato leaves increased with the increase of NaCl concentration,but the content of malondialdehyde in tomato leaves increased with the increase of salt stress time,which indicated that there was residual active oxygen species in tomato leaves.Protective enzymes failed to completely remove active oxygen species from tomato leaves.4.under salt stress,K⁺ in tomato root and stem decreased gradually,while K⁺in tomato leaves increased gradually,and Na⁺in tomato leaf and stem gradually increased with the increase of NaCl concentration.When NaCl concentration was less than 150 mmol/L,Na⁺in tomato root increased gradually,and when the concentration of NaCl reached to 150 mmol/L,the Na⁺in tomato root began to decrease.