Effects Of Different Hardness Culture Media On The Growth And Development Of Several Plant Roots

In many parts of the world today,the soil has been damaged to varying degrees,and the physical and chemical properties of the soil have deteriorated,causing the soil to harden,inhibiting the growth of the root system,affecting the development of the root system,and reducing crop yields.Soil hardening is already one of the important stress factors affecting soil quality and crop growth.Agricultural development and production have brought serious impacts.It is of great significance to study the effect of soil hardness on the growth and development of plant roots.In this study,two models of culture media with different hardness were constructed,and the hardness environment of plant roots in the soil was simulated under laboratory conditions,which were different hardness soil matrix models and different hardness medium models.Pea and tomato were used as materials to analyze the growth and development of the root system to study the effect of medium hardness on root growth and development.Wild type Arabidopsis and peas were used as materials under different hardness medium models to observe the root growth morphology and The effects of different concentrations of DMTU(active oxygen scavenger)on the growth of Arabidopsis roots and the root penetration of peas and Arabidopsis in two different hardness media were used to study the effect of medium hardness changes on plant root growth and development.The relationship between the root growth and development of Arabidopsis,pea,and tomato under the two models was established and related to the above-ground parts,to explore the regulation of medium hardness on plant root growth and development and how the plant root system responded to the medium changes in hardness.The main results of the experiment are as follows:(1)Construction of soil matrix models with different hardness: Use jiffy peat moss soil as the growth medium of the root system,set different soil matrix bulk density,and then measure its hardness.The soil matrix bulk density has a linear positive correlation with matrix hardness.Different hardness media Construction of the model: Phytagel was used as the growth medium of the root system,and mediums with different Phytagel concentrations were prepared,and then the hardness was measured.The Phytagel concentration was linearly and positively correlated with the hardness of the medium.This indicates that two different hardness media models can be used for root growth and development the study.(2)There are significant differences in the development of pea and tomato in different hardness soil matrix models(0.0015 MPa ? 0.4406 MPa).With the increase of matrix hardness,the root fresh weight and dry weight decrease,the main root becomes shorter,and the number of lateral roots decreases The total volume of the root system becomes smaller,the total surface area of the root system becomes smaller,and the total length of the root system becomes shorter,but the effect on the aerial part is small,and there is no significant difference in the chlorophyll content.It shows that with the increase of soil matrix hardness(0.0015 MPa ? 0.4406 MPa),it will inhibit the growth and development of tomato and pea root systems,the main emergence becomes shorter and the number of lateral roots decreases.Since the root bearing capacity of tomato and pea is greater than 0.4406 MPa,the impact on the above ground part is small.(3)The growth and development of Arabidopsis roots in different hardness medium models(0.0584 MPa ? 0.1767 MPa)are significantly different.As the concentration of Phytagel in the medium increases,the hardness of the medium becomes higher and higher,which will inhibit Arabidopsis.The growth and development of the mustard root system is mainly manifested in the shortening of the main root length,the increase in the diameter of the main root,and the decrease in the number of lateral roots.The hardness of the medium within a certain range(hardness0.0584 MPa ? 0.1135 MPa)has a small effect on the leaf area of Arabidopsis,but As the hardness of the culture medium is greater than 0.1135 MPa,the growth of Arabidopsis leaves begins to show dysplasia,indicating that with the increase of the hardness of the medium(0.0584 MPa ? 0.1767 MPa),the growth of the Arabidopsis root system will be inhibited.When the hardness is greater than 0.1135 MPa Will significantly inhibit leaf development.(4)Construct two layers of medium with different hardness,from low hardness to high hardness(Phytagel concentration in the upper layer is 0.6%,0.8%,1.0%,1.2%,and Phytagel concentration in the lower layer is 0.6%.)And high hardness to low hardness(Phytagel concentration in the upper medium is 0.6%,0.8%,1.0%,1.2%,1.4%,1.6%,and phytagel concentration in the lower medium is 0.6%).When the medium grows from low hardness to high hardness,the hardness of the lower layer increases,and the penetration rate of the root system will decrease.When the Phytagel concentration of the lower layer reaches 1.4%,the root system of Arabidopsis will not penetrate,but the pea Part of the root system can penetrate.When Arabidopsis and peas grow from high hardness to low hardness in the medium,as the hardness of the upper-medium increases,the penetration rate of the root system will increase.This indicates that the root penetration of Arabidopsis and peas permeability is related to the hardness of the medium of the growing environment.The harder the medium for root growth is,the stronger the penetrating ability of the root system is.Pea has stronger penetrating and adaptive ability than the root system of Arabidopsis.(5)By staining the ROS in the root system,it was found that as the hardness of the medium increased,the ROS content in the root of Arabidopsis thaliana decreased.This indicates that the hardness of the medium affects the level of reactive oxygen species in the root system.In the growth zone,transition zone,elongation zone,and mature zone,the ROS level in the transition zone was higher.Five different concentrations of DMTU were set under different hardness medium models,which were 0 mmol/L,0.1 mmol/L,1 mmol/L,5 mmol/L,10 mmol/L.Low concentrations of DMTU(0.1 mmol/L and 1 mmol/L)can promote the growth and development of Arabidopsis roots,especially in high hardness media The effect is more obvious.At the same time,with the increase of DMTU concentration,when the DMTU concentration is 5 mmol/L,the growth of the root system is inhibited,and when the concentration reaches 10 mmol/L,the root system almost stops developing.The ROS content of the Arabidopsis root system varies with It indicates that low concentrations of DMTU(0.1 mmol/L and 1 mmol/L)can promote the growth and development of Arabidopsis roots,and high concentrations of DMTU(5 mmol/L and 10 mmol /L)can inhibit root growth.In summary,the hardness of the growth medium regulates the morphology of the plant's root system,and the root system can sense the hardness of the growth medium and make corresponding physiological and morphological changes.Increasing the hardness of the growth medium will inhibit the growth of Arabidopsis,pea,and tomato root systems.Development,leading to shorter main roots,reduced number of lateral roots,reduced root biomass,and affected the energy distribution between the above-ground part and the root system.The penetrating ability of the root system is related to the hardness of the growth medium of the root system.As the hardness of the medium increases,the penetrating ability of Arabidopsis and pea roots is enhanced.Active oxygen can affect root growth and development.Appropriate amount of DMTU in the medium can promote the root elongation of Arabidopsis.The root system has the most obvious promoting effect.This study provides a theoretical basis for the study of the mechanism of soil hardness affecting the growth and development of the root system,it has certain academic value for screening excellent varieties of stress-resistant crops,and it is of great significance to guide the production of agriculture.