| The salinization environment was one of the most serious factors in agricultural production because the salinization soil dispread over a wide area in the world,and the study of plant salt damage and tolerance mechanism had become one of important subject in agricultural scientific research field.The underground ecosystem was an obstacle in the current research of ecology,but the study on its function was still not clear.The root of plant was the connection of above-ground and underground two parts,and had the ability of feeling stress from soil environment.Root growth distribution pattern was adjusted to respond external stress,because this adaptation strategy could increase the survival opportunity in adversity.Jerusalem artichoke(Helianthus tuberosus L.)was a kind of salt-tolerant plants,it had strong stress resistances and wide uses.So it was meaningful to develop Jerusalem artichoke in saline land for improving and increasing cultivable land resources.In this study,the changing of root growth of Jerusalem artichoke related to rhizosphere soil environment presented the mutual adaptation relationship,and provided theoretical support for the mechanism of salt tolerance.One Jerusalem artichoke variety(NY-1)was selected as experimental material to study the root growth distribution pattern in natural salinization field.The enzyme activity and microbial community of rhizosphere soil was also studied to further reveal the root adaption to salt.The root secretion of NY-1 was also explored.The main results were listed below:1.The root growth of NY-1 was barely restrained in the soil salt content range of 0.1%-0.18,and begined to be restrained when salt content achieved 0.2%.The root of NY-1 was mainly concentrated in the vertical 0-15 cm soil layer,and distributed over 30 cm in the horizontal direction,which suggested NY-1 could avoid salt stress by centralizing within a particular range of soil layer and distributed widely in horizontal direction.The root length density in vertical direction had very significant negative correlation with soil pH(P<0.01),soil soluble salt content(P<0.01)and ratio of soil soluble salt and water(P<0.01).The root growth was mainly strained by soil pH(r=-0.602),and then the soil soluble salt content(r=-0.440)and ratio of soil soluble salt and water(r=-0.435).2.The activity of soil urease had very significant positive correlation with root length density(P<0.01),and significant negetive correlation with soil pH(P<0.05).The activity of soil catalase had very significant positive correlation with root length density(P<0.01),and significant negetive correlation with soil pH(P<0.05),soil soluble salt content(P<0.01)and ratio of soil soluble salt and water(P<0.01).The activity of soil invertase had no significant correlation with root length density,but significant negetive correlation with soil pH(P<0.05),soil soluble salt content(P<0.01)and ratio of soil soluble salt and water(P<0.01).3.The composition of soil bacteria was similar in different soil samples,but the proportion of each phylum was certain different.The soil superiority phyla were Proteobacteria,Acidobacteria,Bacteroidetes and Actinobacteria,accounting for more than 80%.Total 643 different genera were found,and 72 genera showed significant differences..4.The root secretion of NY-1 was affected by soil salt content,the root secretions were main straight-chain paraffin in the highest saline field S4,such as pentadecane,n-hexadecane,eicosane,Triacontane,etc,and bare acidic materials.But in the low saline field S1-S3,there were bare straight-chain paraffin secretions.The above results showed that the root of NY-1 was mainly concentrated in the vertical 0-15 cm soil layer,and distributed over 30 cm in the horizontal direction to avoid salt stress.The root growth was significantly affected by soil pH,soil soluble salt content and the ratio of soil soluble salt and water.The soil urease and catalase were significantly affected by soil pH.The soil superiority phyla were Proteobacteria,Acidobacteria,Bacteroidetes and Actinobacteria,accounting for more than 80%.The root secretion of NY-1 was affected by soil salt content... |
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