Fraunhofer Institute for Molecular Biology and Applied Ecology IME
Multipurpose seed coating to safeguard and increase crop yields by protecting and nourishing the seedling.
In times of climate change and limited use of crop protection products, the demands on farmers are increasing, both in organic and conventional agriculture. An important aspect in the transition of plant cultivation are new approaches in seed coatings in order to support early plant development, a very crucial phase for later crop yield.
In order to provide the crop with an advantage over competing weeds, active components play an increasingly important role in new seed formulations. In addition to structural components, e.g., binders or fillers, protective agents like pesticides and repellents, nutrients, as well as germination and growth stimulants, symbiotic soil microbes and soil conditioners (water absorbers) are being integrated into seed coatings. Even though the integration of chemical pesticides in seed coatings has reduced their use during cultivation, further rethinking is required here as well. The alternative to synthetic components lies primarily in the use of natural (biological) starting materials. However, their integration in a coating and effectiveness in the field must first be established and proven on a crop-specific basis.
For the development of innovative, multifunctional seed coatings, we -at the department "Functional and Applied Genomics"- examine the influence of individual components on the respective seed in different formulations. In a first evaluation step we test the material, process and mechanical compatibility of the various compounds. We examine these on the basis of the germination capability of the treated seed under standardized conditions. We record the germination as the sum of the events that begin with the hydration of the seed and end with the formation of the cotyledons.
Figure 1 depicts an example of the influence of a selected coating technology on the germination capacity of the Russian dandelion (Taraxacum koksaghyz). When coated with two different materials, the relative germination rate increased by two percent (material B) and twelve percent (material A) compared to untreated seeds.
Using an alternative coating technology as well as changing the formulations (Fig. 2) led to a significant increase in the germination rates of coated seeds by up to 58 percent compared to untreated seeds for formulations C to F, while coating with formulation G drastically reduced the relative germination rate by 61 percent.
Based on the results of the germination capability, we decide which of the formulations are suitable as binder, filler or active substance for our multifunctional coatings and which technical process should be used to optimally apply the material to the seeds.
In the next step of the evaluation, we examine the performance of the crop through variations and combinations of the coatings in comparison to untreated seed. The performance of the seed and the crop can be investigated using various parameters in the greenhouse and under field conditions. Functional evaluations include herbicide and water uptake by the coating, early seedling development with limited water availability, biomass development after plant emergence, shelf life of the coated seed, and compatibility with conventional seeding techniques. At this stage, crop-specific adaptations and functional enhancements are made in collaboration with our partners by adding to the formulation or changing the structural composition.