Salt-tolerant Hybrid Sorghum Evaluation And The Physiological Machanisms Of Toterances

At present,soil salinization has seriously affected agricultural production,and NaCl is the main component of salinized soil.In this experiment,the salt tolerance of 12 sorghum hybrid varieties was evaluated by culture dish in the experimental artificial climate box,and then two varieties with different salt tolerance were selected to study the salt tolerance mechanism of two sorghum hybrid varieties.The results are as follows:1.The salt tolerance ranking of 12 sorghum varieties participating in the experiment is Longmiliang1>Jinza106>Jinnuo1>Jinza100>Longza17>Longza18>Jinza10>Longza16>Long za10>Liaoza37>Jinza34>Liaonian3.In addition,among the nine traits of this experiment,considered that germination rate,leaf fresh weight and root dry weight could be used as an important index to determine salt tolerance of sorghum varieties.2.The seedling root length,the plant height,the root fresh weight,the root dry weight,the leaf fresh weight and the dry weight under NaCl stress decreased with the increase of salt concentration in the seedling stage of the salt tolerant variety Longmiiang 1 and the salt sensitive variety longza10.Among them,the decline degree of salt tolerant variety Longmilaing1 is lower than that of salt sensitive variety Longza 10.This indicates that salt stress impedes the growth of plants and causes the biomass decline of sorghum seedlings.However,the root length,the plant height and the root fresh weight of Longmiliang 1 have a small increase under low salt stress.Low salt stress may have a certain stress promoting effect on sorghum growth.3.Under salt stress,the content of superoxide anion and MDA in the seedlings of two varieties increased,but the increase of salt sensitive variety Longza10 was obviously higher than that of salt tolerant variety Longmiliang1.In addition,the activity of SOD,POD and MDA in sorghum seedlings increased with the increase of salt concentration,but the degree of enzyme activity in salt sensitive variety Longza10 was obviously lower than the salt tolerant variety Longmiliang1,so the salt tolerant variety Longmiliang 1 could protect the plant membrane better under adverse conditions.The system ensures the normal growth of the plants.4.Under salt stress,the content of osmotic regulation substances in the seedlings of two different salt tolerant varieties increased,and the increase of proline content,soluble sugar content,soluble protein content and free amino acid content of salt tolerant variety Longmiliang 1was greater than that of salt sensitive variety Longza10.In addition,the membrane permeability of the leaves of two sorghum seedlings was also increasing,and the increase of long miscellu Longza10 was much greater than Longmiliang1;the root system vigor of the seedlings decreased,and the decrease of Longmiliang1 was lower than that of the salt sensitive variety Longza10.Longmiliang1 showed better salt tolerance.5.The content of inorganic ions in sorghum seedlings also changed with salt stress.Under the stress of different concentrations of NaCl solution,the content of Na⁺in the seedlings of two varieties with different salt tolerance showed an increasing trend.The content of K⁺decreased,and the content of Ca²⁺and K⁺/Ca²⁺decreased gradually with the increase of salt concentration,and the decline degree of Longmiliang 1 was lower than Longza10.However,the increase of Na⁺content in root Na⁺of Longmiliang1 sorghum is greater than Longza 10,but the increase of Na⁺content in leaves is less than that of Longza10showing a better selection of absorbability.All above proved that the Longmiliang1 can better maintain the ionic balance of cells under salt stress,and has better salt tolerance.6.Under low salt stress(50mmol.L^-1),the content of green pigment in leaves of two sorghum varieties had a small increase.The content of chlorophyll was obviously decreased under the salt(150mmol.L^-1)and high salt stress(200mmol.L^-1).Salt stress was forced to increase the initial fluorescence?Fo?,and the increase of salt tolerant variety Longmiliang 1was less than that of salt sensitive variety Longza10;the maximum fluorescence?Fm?,Fv/Fm and Fv/Fo decreased,and the decrease of salt tolerant variety Longmiliang 1was greater than that of salt sensitive variety Longza10.