Recently, the top international academic journal Science published online research on the mechanism of plant roots in response to soil hardness. The research was conducted by the team leader Professor Zhang Dabing and the research group of Professor Malcolm Bennett from the University of Nottingham, UK. After nearly 7 years of joint research, it clarified the mechanism of how plants respond to the external soil hardness and cultivated crops that adapt to different soil hardness in the future. The new variety provides an important theoretical basis. 

Professor Zhang Dabing is the co-corresponding author, and Dr. Huang Guoqiang is the co-first author. Researchers from the Netherlands, France, Sweden, the Czech Republic and the United States also made important contributions to this research.

With the rapid growth of the world’s population, human demand for food has continued to surge, and the use of inorganic chemical fertilizers has increased year by year, resulting in increased soil hardness, soil compaction and poor air permeability (Figure 1). Plants grow in hard soils, the growth becomes worse and the yield decreases. Therefore, humans have to loosen the soil before planting crops, which consumes a lot of resources.How to cultivate new crop varieties that can adapt to different soil hardness is an urgent problem to be solved.

Figure 1 The difference between loose soil and hard soil

 

(A) Scanning three-dimensional structure map of loose soil, filled with more pores (blue area); (B) Scanning three-dimensional structure map of hard soil, the number of pores is significantly lower than that of loose soil.

Since 1854, scientists have conducted a lot of research in order to explore the mechanism of plant response to external soil hardness. The main point of view is that the response of plants to external soil is a passive process, and the growth of plant roots is determined by the mechanical hardness of the soil. 

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Therefore, people think that it is an unattainable goal to cultivate new crop varieties that can adapt to different soil hardness.

 

 

This work first established a soil system with different hardness and found that the growth of the rice root system in the harder soil was hindered, and the root system became shorter and thicker. 

Through in-depth research, it is found that the number of soil pores is the key to determining loose soil and hard soil. Focusing on the characteristics of loose soil and hard soil, scientists have carried out a series of explorations, especially using experimental methods such as cell biology, genetics, chemistry, etc., to prove that high hardness soil can limit the diffusion of ethylene produced by the plant itself, leading to ethylene accumulation Around the root system, the growth of the plant root system is inhibited, and the response to the external soil hardness is achieved (Figure 2). In addition, this mechanism of plants adapting to soil hardness is highly conserved among different species such as rice, maize, and Arabidopsis. This new discovery clarifies the mechanism of how plants actively respond to the hardness of the external soil, opening up new ideas for molecular design and breeding.

Figure 2 Working model

(A) Rice grows in loose soil; (B) Rice grows in hard soil.