IES’s researchers have developed methods to help herbs and vegetables outgrow weeds

The researchers of the Institute for Environmental Solutions (IES) have developed accelerated seed germination method. This organic farming method allows valuable but slow-sprouting herbs and vegetables to outcompete weeds, thereby raising the quality of yield. The research was carried out in cooperation with farming experts SIA “Vidzemes mežsaimnieks” and SIA “Damuižnieki”.

The speed of seed sprouting directly affects the efficiency and quality of the yield. Raised competitiveness of newly sprouted seeds means healthier and more productive plant formation, thereby also contributing to the increased yield. For this research were selected species which seeds sprout relatively slower (14 – 24 days) – dill, coriander, thyme, pot Marigold, carrot and onion. These plants have high market demand, however because of slow seed sprouting, their cultivation is not efficient.  IES’s researchers have adapted accelerated seed germination method for organic farming, which previously has been mainly used only in forestry.

The method development was divided in three steps. First, pre-sowing seed processing or germination that accelerates the sprouting of plants once they are sown in field. Second, germinated seed coating with protective layer that allows to carefully deliver germinated seeds into the soil. Third, growing tests with germinated and coated seeds in laboratory and field conditions. During this step, the researchers tested the growing difference of germinated seeds that were coated with protective layer and seeds without additional preparation.

IES’s leading researcher Dr. Ieva Mežaka describes the importance of this research: “Not all seeds can sprout within a few days. For this research we chose herbs and vegetables that usually takes a longer period to sprout. Therefore, weeds manage to sprout faster and overtake the plants. The cultivation of such plants in organic farming is almost impossible. During two-year period, we were researching possibilities to sprout the seeds before sowing. This approach allows them to sprout faster once sown in soil, thus increasing their competitiveness against weeds.”

Pre-sowing seed processing or germination was the first major step in the method development process. Researchers germinated seeds in climate cameras where controlled environmental conditions such as temperature, humidity and light can be provided. Pre-sowing seed processing method was adapted to each of the selected plant species. It was necessary because not only environment conditions affect the germination, but also such factors as seed quality and harvesting time. Researching each herb and vegetable seeds separately allowed the researchers to find the most suitable germination conditions for each species – environment, duration, etc. For example, researchers tested different germination environments by soaking the seed in water or in aqueous liquid with added substances. This approach allows the seed to become physiologically active, thereby sprouting in field conditions is faster than the not processed seed.

As Dr. Ieva Mežaka highlights, “For seed processing method to meet the standards of organic farming, it must be safe, easily applied by growers and have as little impact on the environment as possible. After tests in controlled conditions, we found out that a seed is sprouting much better when its’ root has already germinated. Thus, this technology of accelerated germination of seeds can be considered the most successful one. If seed that has germinated its radicle is sown into soil, it sprouts faster and can outcompete weeds. We also concluded that this method is suitable for all herbs and vegetables included in this research – dill, coriander, thyme, pot Marigold, carrot and onion.”

Second step of the research was to find solutions how seeds with already germinated radicle can be carefully delivered into the soil. Moreover, so it could be done mechanically, not manually. Regular farming practice is to sow dry seeds that has their protective outer layer. Germinated seeds when the radicle is already sprouted are no more vulnerable. IES’s researchers tested different solutions how do germinated seeds could be coated, so the seed and radicle would be safe from possible damages during the sowing process, but at the same time the further sprouting would not be delayed.

Dr Ieva Mežaka explains this process: “we conducted several series of test, looking for different types of coating of sprouted seeds – pharmaceutical capsules, pelleting with various thickeners, coating in alginate capsules and liquid capsules. Then, in laboratory conditions we evaluated how coated seed sprouting continued in the soil. Furthermore, we tested seed coating solutions with best results by sowing them in the test fields.”

Idea of already germinated seed coating and sowing was adapted from a forestry company Denra systems. The company germinates tree seeds and coats them with capsules, then, sow the seeds using drones to access hard-to-reach areas. “This method is used in forestry but for farming this is innovative approach. Germinated seed coating for farming purposes is mentioned in a single research,” Dr Ieva Mežaka explains the relevance of the study.

Theoretical assumptions provided by the research in laboratory do not provide a complete insight into how the methods work in field conditions. The researchers went a step further and tested the developed method in real agricultural conditions by sowing the germinated and coated seeds in the field. The environment in the laboratory can be controlled, but it is much harder to predict environmental and climate factors in nature. Weather conditions such as drought and severe rainfall are more and more common in Latvia. In field tests, the researchers compared growing progress of germinated and coated seeds with not previously prepared seeds. Especially they were focusing on testing how successful are dill, coriander, thyme, pot Marigold, carrot and onion in outcompeting the weeds and how differs their yield in field conditions. The researchers concluded that two germinated seed coating methods are suitable for organic farming – alginate and liquid capsules.

Dr Ieva Mežaka explains results of germinated and coated seed tests in field conditions: “alginate and liquid capsules have shown the most promising results. Alginate capsules are suitable for pot Marigold, thyme, carrot and dill germinated seed coating. Liquid capsules are suitable for onion, carrot, coriander and dill seeds.”

Within this research IES’s researchers have developed the method that allows valuable but slow-sprouting herbs and vegetables to outcompete weeds, thereby raising the quality of the yield. “Within this research we had a small-scale field study. The results are promising. By applying each step of this method, farmers can grow dills, coriander, thyme, pot Marigold, carrots and onions in both organic and conventional farming. Developed method also includes economic justification for the cultivation of each species. This is an important aspect for farmers that are considering the possibility of the herbs and vegetable cultivation. We also have presented our research approach and the developed method in the  conference “Balanced agriculture 2021” hosted by the Latvia University of Life Sciences and Technologies,” reveals researcher Dr Ieva Mežaka.

Innovative seed preparation technologies for pre-sowing and sowing of slow growing plants are developed as part of EU European Agricultural Fund for Rural Development, Rural Development Programme 16. action “Cooperation” 16.2. sub measures “Support for new products, methods, processes and technologies” supported project “New seed preparation technologies for pre-sowing and sowing” (Nr. 18-00-A01620-000051).

More about the project here.