1) The influence of humic acid on crop root morphology.

Humic acid can promote plants to increase the number of root, change the cell size and type, increase the number of lateral roots and absorptive pores to promote root growth.

Humic acid can induce the increase of H⁺-ATP ase in crops, loosen the cell wall and promote cell extension.

The low molecular weight humic acid has better biological activity and is easier to improve root structure and promote root growth.

2) The effect of humic acid on nutrient absorption of crop roots.

Humic acid can increase the activity of root H⁺-ATP ase, promote the absorption of ions and nutrients, and increase the transport capacity of ions.

Humic acid can promote the growth of roots and increase the surface area of roots, so that the roots can better absorb and utilize mineral nutrients.

3) The effect of humic acid on the expression of crop roots

Humic acid has a physiological function similar to auxin and gibberellin. It also participates in the process of these two types of hormones to induce cell division and expansion.

Humic acid affects various metabolic pathways in crops, such as hormones, carbon and nitrogen metabolism, stress response, etc.

4) The effect of humic acid on crop rhizosphere microorganisms

Humic acid can affect the microbial film, thereby affecting the structure and activities of the microbial community in the soil.

Humic acid can also chelate unusable nutrients, buffer the pH of the soil, and affect the microbial community.

At present, the research methods on humic acid are advanced, but humic acid is a type of substance, and there is still much room for improvement in the study of its structure. The interaction between humic acid and soil makes the secretion of hormones by soil microorganisms still inconclusive, and further research is needed in the later stage. let us wait and see.