Photo Jean-Marc Sanchez

by Jean-Marc Sanchez

Directeur Marketing Technique

Numerous beneficial microorganisms, which can be described as probiotics, are present in soils. They are most numerous in the area of the soil in the immediate vicinity of the roots, known as the rhizosphere. These rhizospheric microorganisms live in partnership with the roots and provide them with services such as increasing nutrient availability and plant uptake capacity and can therefore positively impact yields, plant resilience or help fight pathogens.

We will explain how these organisms work.

The term probiotic was first used in the 1960s to describe the capacity of certain microorganisms to synthesize natural substances, providing beneficial effects on the production and growth of plants.

As opposed to antibiotics, which kill bacteria, probiotics encourage bacterial life by inoculating beneficial strains of microorganisms. As for the harmful microorganisms, which are called pathogens, they find themselves in competition and their potential to spread becomes limited. In both the animal world and the plant world, the majority of microorganisms are actually beneficial, as opposed to pathogenic.

1 - Microorganisms in the rhizosphere

Microorganisms in the rhizosphere interact with the plant through its roots. That is where we find the richest microbial flora, and here we can draw a parallel with the human intestine, which is teeming with flora that is as essential as it is fascinating. Roots act like an inverted intestine, with absorbent hairs that are surrounded by large microbial colonies. The roots release exudates specifically to attract and stimulate these microorganisms that are beneficial to the plant.

Rhizobacteria are like the intestinal flora of plants.

2 - Bacteria encourage plant growth

Within this type of flora, there are bacteria that are able to stimulate and/or protect the plant with one or several different mechanisms: excretion of phytohormones into the environment, solubilization of minerals caught in the soil, atmospheric nitrogen fixation, reduction of the number of certain pathogens in the soil (due to competition or hyperparasitism, etc.).

For example, some Bacillus are very effective at solubilizing phosphorus. These bacteria are particularly useful when there are increased phosphorus requirements in soil with a high pH level, where phosphorus tends to become attached to calcium. This is even more true for short-cycle vegetable crops, such as lettuce, cauliflower or artichokes, which have immediate requirements for high levels of nutrients. The bacteria effectively enable them to find the minerals they need immediately and absorb the phosphorus more easily, leading to yield increases of up to 20%.

3 - Mycorrhizae

Other microorganisms specifically stimulate root growth in plants, thus increasing their absorption capacity. An improved root system promotes better nutrition as it is more effective at finding water and nutrients in the soil, leading to increased yields for farmers.

It is mycorrhizal fungi in particular that are able to develop a symbiotic relationship with plants.  These fungi penetrate the inside of the root, which is where exchanges will take place. The plant transfers to the fungus the sugars obtained through photosynthesis that it cannot synthesize itself. Simultaneously, the fungus develops a network of microscopic filaments that are able to infiltrate all the gaps throughout the soil and significantly extend the roots of the host plant, increasing its exploration area and reducing the energy it would expend through producing its own roots. This mycelial network will gather and provide the plant with the water and nutrients that it needs. And we now know that exchanges between different plants can also take place via the mycelial network. Various different trees in the same forest can connect to each other in this way.

The above video demonstrates how MYCONNECT technology is used in the production of mycorrhizal inoculants at Lallemand Plant Care.

The use of mycorrhizal fungi is effective in perennial plants (viticulture and arboriculture) and particularly in soil that poses difficulties for root exploration or that suffers from water shortage.

the mycorrhizae form a network of microscopic filaments to increase the area of root exploration

4 - Working in synergy

LALLEMAND PLANT CARE has demonstrated that Bacillus and mycorrhizae are particularly effective when they work together, providing access to more nutrients and increased benefits.

The combination of LALRISE MAX WP and LALRISE VITA provides additional benefits, thanks to their combined action. Via the hyphal network produced by LALRISE MAX WP, the active ingredient in LALRISE VITA is able to release (make available) a much larger quantity of nutrients and channel higher levels of them to the plant, thus increasing their benefits. 

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Stay in the loop - part 2