The growing economic importance of the wheat crop should continue in the 2023 harvest, with an increase in areas under cultivation and investment. In Rio Grande do Sul, wheat has become the most popular alternative for winter cultivation.
Within the crop, management practices such as seed treatment and nitrogen fertilization (base and cover) are important practices. The use of chemical fungicides and insecticides in seed treatments guarantees safety in the initial phase of the crop with an adequate stand, as it prevents plant losses from attack by diseases and pests. The proper use of fertilizers stands out among the management practices, especially nitrogen topdressing and losses due to application carried out in unfavorable climatic conditions.
In view of this, some technologies have been drawing attention as alternatives to optimize chemical fertilization, such as the use of beneficial microorganisms, in particular the so-called plant growth promoting bacteria (BPCV).
Among these bacteria, the most prominent among grasses is Azospirillum brasilense, an efficient microorganism in the production of phytohormones and nitrogen (N) fixation. It acts by increasing the development of the root system, increasing access to water and nutrients in the soil, in addition to helping the plant to supply the N necessary for development and production.
Another BPCV that has been gaining ground is Pseudomonas fluorescens. This microorganism is an efficient producer of organic acids, which helps in the solubilization of nutrients in the soil, mainly phosphorus, acting on molecules adhered to the soil and making it available for the plant to be able to absorb and use in its metabolism. Some species of Bacillus sp. are also being used in the treatment of seeds (ST) of wheat, mainly in areas where there is already a history of soil diseases. Bacteria of the genus Bacillus produce protection in the root system, called biofilm, which helps promote growth and defend the plant against soil phytopathogens.
The process of treating seeds with biological products requires some basic care, especially when using more sensitive microorganisms, such as Azospirillum brasilense and Pseudomonas fluroescens. These microorganisms do not allow mixing with chemical products, therefore, the biological treatment must be done separately from the chemical one. It is possible to use nutrient-based products together with the biological one, but we must pay attention to the pH and salinity of the nutritional product, knowing that the optimal pH of these microorganisms is on average 6.0 to 6.5 and high salinity can damage the bacterial cells.
After carrying out the biological treatment, it is recommended that sowing takes place within 24 hours, because products based on A. brasilense and P. fluorescens are live bacteria, therefore sensitive to the environment. In addition, the treated seed must be stored in a place protected from solar radiation.
Treatment with biological products, which cannot be treated in advance or together with chemical products, must be carried out separately and on the day of sowing.
In addition, there are alternative ways of using these microorganisms in wheat seeds, as is the case of using a directed jet in the crop's planting furrow. This is a technique that is growing and has been adopted by commercial crops due to its versatility and inoculation efficiency. In cultures such as soy and corn, it is one of the most used forms of biological treatment.
Another way to apply it is with the use of a bag inoculator. This technique requires prior treatment planning, but it is a practical way to treat seeds in the field, and is currently the most used technique in the biological TS of wheat. The use of inoculant in peat in the seed box is also a form of treatment, but it has been losing space for liquid treatment due to the homogeneity of seed treatment.
Within the 3tentos Research Center, over four seasons, significant increases in wheat productivity were observed when inoculants were used in seed treatment. As we can see in the test below, there was an increase of up to 6% in crop productivity in 2021.
New technologies are being made available to assist in the management of farmers, therefore, identifying their benefits and ways of using them are extremely important. Basic care with use and application allows us to explore the maximum potential in search of new levels of productivity, with profitability and sustainability.
