The influence of humic acid on plant physiological activities

Humic acid is the remains of plants and animals, mainly plant remains. Microbial decomposition and transformation of formation and chemical process of organic matter. Humic acid is divided into water-soluble fulvic acid, ethanol soluble ulmic acid and alkali soluble humic acid.1

Humic performance is acidic, so can be  dissolved in alkaline solution. From the extent of evolution of organic matter (sludge and plaster) obtained humic acid, higher aliphatic characterized in having a higher content of nitrogen compounds, low degree of oxidation, heterogeneous composition. Relatively low molecular weight of fulvic acid(300~400), medium molecular weight of brown rot acid(2×103~104), Relatively high molecular weight for black rot acid(104~106). The humic acid was also divided into low molecular weight components(<5KDa)and high molecular weight components(>5KDa). It is generally considered a low molecular weight component having a high biological activity. Because humic acid is not uniform, so there is no clear structure, representing the views of workers is at the center of an aromatic or aliphatic group and a phenolic hydroxyl group is connected, polypeptides and carbohydrates, as well as chelated metal ions. People study humic acid are manifold: as with chemical analysis and spectroscopy qualitative analysis of humic acid, humic acid interaction with Al3 application in acidic soil, and in water purification, medical, and other .

Effect of humic acid on plant growth

The main physiological function of humic acid is stimulating the growth of plants.

Effect of humic acid on the growth of intact higher plantsABUIABACGAAghPqVrgUo3J35iAQwgAg49gU

In seedlings experimental results show that the humic acid on height growth rate, total dry matter yield has greatly improved. Such as wheat, tomatoes, cotton, especially sodium humic acid has a great effect on root growth.

In general case,  the stimulating effect of humic acid on the root is greater than the stem leaf. According to the sensitivity of crops to humic acid stimulation, the crop is divided into several types, sensitive crops:  cabbage, radish, tomato, potato, sugar beet, sweet potato etc. Sensitive crop: corn, rice, wheat, millet, sorghum, oats etc. Response is not sensitive to crops: rapeseed, sunflower and flax.

The humic acid from peat is only  stimulate the growth of root invalid to shoot, and from lignite obtained on root and shoot growth can promote.

Humic acid concentration, with similar growth hormone, also showed low concentrations of humic acids promote high concentration inhibited.

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