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Study On The Response Of Iris Lactea Var.chinensis To Mixed Saline Stress And The Improvement Effect Of Saline-alkali Soil

Posted on:2021-02-06Degree:MasterType:Thesis
Country:ChinaCandidate:Z B YuanFull Text:PDF
GTID:2370330605475147Subject:Landscape architecture study
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The increasing area of saline alkali soil has seriously restricted the production and development of agriculture.Iris lactea var.chinensis is a perennial herb of iris,with omamentai,ecological and economic value,which hasgood resistance and wide adaptability.It is a excellent gardening plant,and its application in improving saline-alkali soil has also become a research hotspot in study.The effects of NaCl and NaHCO3 solutions with a total concentration of 0.3%on plant water content,growth,root structure,physiological and biochemical indexes were studied of Iris lactea var chinensis seedings as the test material.The most severe stress treatment was selected,and the transcriptome of the differentially expressed genes of seedlings under saline stress was analyzed,At the same time,the remediation effect of Tris lactea var.chinensis seedings on saline-alkali soil was also studied.The purpose is to explore the salt-tolerance mechanism of Iris lactea var.chinensis under mixed saline stress,and provide theoretical basis and technical support for the utilization of Iris lactea var.chinensis in improving saline-alkali soil.The main findings are as follows:(1)The SPAD value measured from seeding leaves under salt stress treatment showed a trend of first increase and then decrease with the prolongation of stress.The SPAD value of 0.3%NaHCO3 and 0.1%NaCl+0.2%NaHCO3 treatment decreased significantly on the 35th day of stress.0.3%NaCl solution has the smallest effect on the number of leaves and the growth of plant height,and each treatment has the largest increase in plant height on the 14th day.After 0.3%NaHCO3 treatment,the water content of the aboveground part of seedlings is 0.83 times of the blank control,while the underground partwas 1.10 times.With the concentration of NaHCO3 increase in the mixed solution,the water content of aboveground part showed a downward trend,while the water content of underground part showed an upward trend.After 35 days of treatment,the root length and root surface area of 0.3%NaHCO3 stressed iris seedlings decreased significantly compared with the control,with a decrease of 39.73%and 26.08%respectively,but the root volume of each treatment had no significant difference(2)The proline content in the seedling leaves with saline stress treatment showed a trend of first increase and then decrease with the prolonged stress.The maximum value of proline content of 0.3%NaHCO3 and 0.1%NaCl+0.2%NaHCO3 treatment was higher than that of other treatments.The MDA content of each treatment increased significantly.On the 35th day,the MDA content of the seedlings treated with 0.3%NaHCO3 treatment reached 2.05 mmol·g-1,which was 2.32 times of that of the blank control group,and the lowest was 0.3%NaCl treatment.The effect of different salt combinations on soluble protein was different;.In the influence of salt solution on the content of soluble sugar,the concentration of NaCl is the dominant factorand the change range of soluble sugar in seedlings treated with 0.3%NaCl treatment was the largest,which was 2.65 times of that in blank control group on the 35th day;.The activity of SOD in leaves with saline stress showed an overall upward trend during the stress period,and the highest one was 0.3%NaHCO3 and 0.1%NaCl+0.2%NaHCO3;.The CAT activity of each treatment increased gradually in the early stage of stress,then decreased continuously in the later stage.The activity of POD decreased first,then increased and then decreased,and the highest increase was the treatment of 0.3%NaHCO3 and 0.3%NaCl.It was speculated that there might be synergism between SOD and POD in the process of eliminating active oxygen in Iris lactea var.chinensis under saline stress.A comprehensive evaluation of physiological and biochemical indexes under saline stress using the membership function method showed that 0.3%NaHCO3 was the most severely stressed to the stables.(3)The number of down-regulated genes was more than up-regulated genes in the differentially expressed genes of Iris lactea var.chinensis seedlings under salt stress,indicating that the expression of some genes would be inhibited under saline stress,while some genes responded to the damage caused by saline stress by up-regulated expression.According to GO function analysis,the differentially expressed genes are mostly related to cell components,which indicates that Iris lactea var.chinensis can stabilize the internal environment under salt stress by maintaining the balance between the components in the cells.KEGG enrichment analysis showed that the most differentially expressed genes were the metabolic pathways of starch and sucrose,and the most significant enrichment was the degradation pathways of other polysaccharides,indicating that carbohydrates may play a major role in the process of Iris lactea var.chinensis responding to saline stress.(4)After 90 days of planting,the pH value of the saline alkali soil collected from area ?,area ? and Area ? decreased by 0.363,0.360 and 0.530 respectively,and the desalination rate reached 3.03%,8.13%and 11.64%respectively;the content of organic matter,total nitrogen,available phosphorus and available potassium in the saline alkali soil also increased significantly.The growth of Iris lactea var.chinensis was the best when it was transplanted in the saline alkali soil of the region ? with the lowest salt content.The results showed that Iris lactea var.chinensis had a certain improvement effect on saline alkali soil.
Keywords/Search Tags:Iris lactea var.chinensis, Salt stress, Physiological and biochemical indicators, Transcriptome, Saline alkali soil improvement
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