A Brief Discussion on Biostimulants

The European Biostimulants Industry Committee (EBIC) defines biostimulants as substances containing certain ingredients and/or microorganisms that, when applied to crops or around their rhizosphere, can promote the natural physiological metabolism of crops and enhance nutrition. Absorption and utilization of substances, improving abiotic stress resistance, and improving quality and yield.

On the basis of active ingredients, the biostimulants market is segmented into humic acid, fulvic acid, amino acids, protein hydrolysates, and seaweed extracts.

The targets of biostimulants are the crops themselves and the soil environment where they are located. They mainly act on the entire life cycle of crops from seed germination to mature harvest through multiple pathways. Biostimulants function very differently compared to traditional chemical pesticides and fertilizers.

According to reports in relevant literature, its main functions are summarized into the following five points:

1. Promote plant growth by enhancing the absorption and transportation of nutrients;
2. Improve plant disease resistance and stress resistance by enhancing plant immunity;
3. Regulate and improve the water balance in plants;
4. Improve the physical and chemical properties of soil, protect and improve soil, and promote the growth of beneficial soil microorganisms;
5. Improve the quality (sugar content and color) of agricultural products and extend the storage time, etc.

It is worth noting that plant biostimulants have similar functions to plant growth regulators in the traditional concept, but they are also different. Compared with plant growth regulators, biostimulants have wider sources and more diverse functions. Plant biostimulants not only act on plants, but also on soil and soil microorganisms. More importantly, biostimulants increase the metabolic process of plants without changing the original metabolic pathways of plants.

The most common biostimulants on the market are amino acids, alginic acid, and humic acid.

1. Amino acids

Amino acids are small molecule organic nutrients converted from plant protein or animal protein. They can be directly absorbed by crops and are organic nitrogen sources. After the crops are used, the leaves will become larger, greener, and thicker; the fruits will also increase in size; the taste will be increased, the quality will be improved; the crop resistance will be improved, and the soil will also be improved.

Multiple experiments on a variety of crops have shown that amino acid organic foliar fertilizer can indeed significantly increase crop yields, effectively increase the soluble sugar content of the product, reduce the NO3ˉ content, and improve the absorption and utilization of nitrogen, phosphorus, and potassium.

2. Alginic acid

Alginic acid is a natural polysaccharide, mostly extracted from kelp and seaweed. It exists in the cytoplasm under normal conditions and can strengthen the cell wall, thereby comprehensively regulating the physiological functions of plants, promoting crop metabolism, and improving photosynthesis. The efficiency of the action promotes the growth of crops.

As a powerful crop stimulating factor, alginic acid enhances the cold resistance, drought resistance and other stress resistance of crops by regulating ABA (abscisic acid)-dependent signaling pathways.

3. Humic acid

Humic acid is a natural organic macromolecular weak acid extracted from coal. It needs to be converted and absorbed by crops. After application, it can adhere to the surface of sand and other minerals, retain water and fertilizer, and promote soil improvement. It is especially suitable for barren soils such as sandy soil and loess soil.

Humic acid contains 90% carbohydrates, and the main component of carbohydrates is glucose, so it will make the fruit sweeter; it will also increase the proportion of carbon in the dry matter of the crop, thus increasing the weight of the fruit.