| In recent years,water pollution is a major global problem,mainly due to the eutrophication of industrial wastewater(organic,heavy metals,etc.),agricultural irrigation water(rich in nitrogen,phosphorus,etc.),and domestic waste water discharge.Micro-nano bubble technology is one of the innovative water treatment technologies developed in recent years.According to the characteristics of micro-nano bubbles,it has a good control effect on pollution phenomena such as eutrophication of water and black odor of water.In the water treatment project carried out by the research team from 2014 to 2016,it was found that the micro-nano bubbles have an effect on the growth rate and growth quality of the plant-type ecological restoration plants.This paper further experiments from three aspects: 1.Investigate the influence of micro-nano bubbles on plant growth;2.Explore the mechanism of micro-nano bubbles to promote growth;3.Explore the effects of micro-nano bubbles on plant growth from the genetic level for the first time.Three kinds of different types of aquatic plants(Iris pseudacorus L,Eichhornia crassipes and Elodea nuttallii)were selected to explore the growth and quality of plants that it used by micro-nano bubbles cultivation.The physiological indicators of the three plants were compared after 60 different incubation cycles,The results showed that the six physiological indexes of the experimental group were higher than the control group: 1.The content of catalase: Iris pseudacorus experimental group was about 39.8% higher than the control group,Eichhornia crassipes experimental group was higher about 22.7%,Elodea experimental group was about 31.1% higher;2.The content of Proline: the Iris pseudacorus was 1.52 ?g/g higher,the Eichhornia crassipes was 1.21 ?g/g higher,and the Elodea was 1.83 ?g/g higher.3.The rate of respiration : experimental group of Iris pseudacorus was higher 34.9%,the Eichhornia crassipes was 28.4% higher,and Elodea was about 15.3% higher;4.The percentage of soluble sugar: Iris pseudacorus was 1.19% higher,Eichhornia crassipes was 0.57% higher,Elodea was 0.19% higher;5.The content of peroxidase: the experimental group is higher than the control group 44.1% of Iris pseudacorus,Eichhornia crassipes is 23.3% higher,Elodea is 42.01% higher;6.The content of chlorophyll: The experimental group of the Iris pseudacorus was higher than the control group,the chlorophyll a was 35.88% higher,the chlorophyll b was 29.51% higher,the carotenoid was higher than 34.27%.And the chlorophyll content of Eichhornia crassipes was slightly higher than that of the control group,the chlorophyll a was 24.74% higher,the chlorophyll b was 14.06% higher,the carotenoid was 25.87% higher.The content of chlorophyll b of Elodea was basically the same as that of the control group,and the other two groups were 22.04% and 29.05% higher than the control group respectively.However,the experimental groups of the following three indicators were lower than the control group: 1.The rate of superoxide anion production: the experimental group of Iris pseudacorus only accounted for 66.15% of the control group,the Eichhornia crassipes and Elodea accounted for 79.45% and 76.87% of the control group,respectively.2.The index of relative conductivity: the average value of the experimental group of Iris pseudacorus accounted for 58.58% of the control group.The average value of Eichhornia crassipes and Elodea accounted for 63.35% and 64.61% of the control group,respectively.3.The content of relative water: compared with the experimental group,the Iris pseudacorus was 4.07% higher,the Eichhornia crassipes was 1.98% higher,and the Elodea was 1.07% higher.In summary,from the effect of the micro-nano bubbles on the growth of plants,the physiological indicators of the comparison of showed that the micro-nano bubbles promoted the growth of Iris pseudacorus are more effective.The experiment explores the growth-promoting mechanism of micro-nano bubbles on Iris pseudacorus by controlling the concentration of micro-nano bubbles.The experimental results show that the active oxygen released by micro-nano bubbles and the increase of dissolved oxygen in water are one of the reasons for promoting the growth of Iris pseudacorus.Oxidative stress is induced on plant growth,and the oxidative stress pressure changes with the concentration of micro-nano bubbles.When the concentration reaches about 50-70%,the optimum concentration exists.The appropriate concentration of Iris pseudacorus is weak due to long-term stress,so it is easier to enhance the function of plant tissues and plant growth when plant by resisting external stress.In addition,there is a affect that other gas in the micro-nano bubble when plants growth.For example,the dissolution of micro-nano bubbles in water increases not only the oxygen content,but also the carbon dioxide content,which is an important molecule for plants to store energy,respiration and plant signaling systems.Therefore,the mechanism by which carbon dioxide acts on plants is also to be studied.Exploring the plants differences in transcriptome sequencing can directly the causes of micro-nano bubbles affecting plant growth.In the transcriptome sequencing,comparing the quality assessment(FastQC),the randomization results(gene homogenization distribution curve),the gene expression level(gene expression density curve)and gene differential expression(gene coverage,gene expression difference scatter and GO difference gene function annotation).The results showed that the different cultivation methods of the two Iris pseudacorus caused differences in gene expression.For example,differences in biological functions such as Membrane,Symplast,Nutrient reservoir activity and Transporter activity.The more detailed study of gene function needs further experiments. |
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