Distribution Of Na~+ In Sweet Sorghum Plants And Establishment Of LIBS Analysis Method

Na~+occupies an absolute predominance in the salinity of salinized soil,and it plays an important role in soil structure deterioration and plant growth inhibition.This paper explores the feasibility of using LIBS technology to quickly detect the distribution of sodium in sweet sorghum,and studies the characteristics of Na~+distribution in sweet sorghum plants under different salt stresses,and analyzes the advantages of hybrid sweet sorghum in improving saline-alkali soils.The main findings of the thesis are as follows:1.Optimized and determined the conditions for the rapid detection of Na~+in sweet sorghum by LIBS:the laser energy is 20 m J,the laser ablation point is 1mm below the sample,and the delay time is 1.2?s.The partial least squares algorithm was used to establish the calibration curve of each organ and the whole material.The linearity of the calibration curve detected by LIBS and chemical methods are:leaf sheath R~2=0.95,leaf R~2=0.85,stem R~2=0.95,root R~2=0.88 and the overall calibration curve R~2=0.88,the two have a good correlation.In addition,the sample pretreatment with crushed pressed cake is more accurate than the direct use of LIBS to detect sweet sorghum materials.The laser directly ablated the surface of the sample.With the change of the ablation position,the characteristic spectral intensity of Na of the leaves did not change significantly,while the characteristic spectral intensity of Na of the stem and root changed significantly.In addition,the sample pretreatment with crushed pressed cake is more accurate than the direct use of LIBS to detect sweet sorghum materials.2.Under varying degrees of saline-alkali soil stress,the distribution of Na~+in sweet sorghum plants showed the characteristics of root>stem>leaf>leaf sheath,hybrid sweet sorghum(BJ0603)and conventional sweet sorghum(623B)under mild salt stress in the field and under salt stress in pots.Showed the same trend,and the approximate ratio of Na~+concentration in each organ was root:stem:leaf:leaf sheath=6.5:2.8:1.1:1.Therefore,it can be seen that the two varieties of sweet sorghum both reduce the influence of Na~+on plant growth and development in saline-alkali soil by fixing Na~+by the roots and reducing the movement of Na~+to the upper part of the ground.3.Compared with conventional sweet sorghum,hybrid sweet sorghum can obtain greater growth advantages by reducing the Na~+concentration in roots,stalks,leaves and sheath tissues,that is,showing obvious growth advantages and biological yields,whether in the field or in pots.The increase range is 74%-194%,and more Na~+is actually"removed"from the soil,and the Na~+content absorbed by each plant is relatively increased by 40%-99%.Hybrid sweet sorghum uses heterosis and adapts to the growth environment of saline-alkali soil through the strategy of"dilute salt".