We explored two methods for obtaining aqueous extracts: boiling and soaking of Baltic seaweeds (EB and ES, resp.). Algal extracts were characterized in terms of polyphenols, micro- and macroelements, lipids content, and antibacterial properties. The utilitarian properties were examined in the germination tests on Lepidium sativum for three extract dilutions (0.5, 2.5, and 10%). It was found that the extracts were similar in micro- and macroelement concentrations. Water was proved to be a good solvent to extract phenolic compounds. The algal extract produced by soaking biomass did not show inhibitory effect on Escherichia coli and Staphylococcus aureus. Only the boiled extract had an inhibitory activity against E. coli. Germination tests revealed a positive influence of the bioproducts on the cultivated plants. In the group treated with 10% EB, plants were 13% longer than in the control group; the content of elements B, Mo, Zn, and Na in the group treated with 10% ES was higher by 76%, 48%, 31%, and 59% than in the control group, respectively; the content of chlorophyll was 2.5 times higher in 0.5% ES than in the control group. Extracts showed the slight impact on the morphology of plants.

The aim of this study was to investigate the potential of using natural raw materials that have not been used for the production of biostimulants of plant growth. These products can effectively contribute to overcome the challenge posed by the increasing demand for food. Ultrasound assisted extraction (UAE) was chosen to prepare innovative biostimulants. The expected outcome of this research was to generate products that show beneficial effects on white head cabbage growth, development, and nutritional quality. The results proved that higher plants (mugwort, calendula, purple coneflower, chamomile, basil, giant goldenrod, comfrey, dandelion, and valerian) can be successfully used for the production of biostimulants. For example, products based on common dandelion showed the highest biostimulating activity. In a group treated with 2.5% flower extract, cabbage shoots were 37% longer, whereas in a group treated with 0.5% leaves extract, roots were longer by 76% as compared with a control group treated with water. Biostimulants based on common mugwort (at a dose of 0.5%) and common dandelion (root) (at a dose of 1.0%) increased the mass of cabbage shoots and roots by 106% and 246%, respectively. The majority of biostimulants increased the content of photosynthetic pigments (chlorophyll and carotenoids) and decreased the content of polyphenols. Botanical extracts also showed varied impact on the antioxidant activity of cabbage. Taking into account the benefits for a wide scope of applications, it is expected that the utilization of these types of products should increase in the future. These products can play a key role in sustainable agriculture.

This research presents the possibility of using innovative botanical extracts as biostimulants of plant growth to improve plant nutritional value, growth, and development. It is important to increase agricultural production but this process should be carried out in a sustainable way, without causing risks for both the environment and consumers. For this reason, we have focused on the use of 14 natural raw materials and ultrasound assisted extraction for the production of biostimulants. Results proved that higher plants can be used to obtain valuable products for the application in modern horticulture and agriculture. For instance, extract based on Urtica dioica L. showed the highest biostimulatory properties: in the group sprayed with 0.1% extract cabbage seedlings were longer by 31%, while with 1.0% extract of Polygonum aviculare L. roots were longer by 72% than in the control group treated with water. Extracts based on Equisetum arvense L. (0.5%) and Urtica dioica L. (leaf) (0.1%) increased the fresh weight of sprouts by 113% and 112%, respectively. The highest root weight was observed in groups treated with Equisetum arvense L. (0.5%), Polygonum aviculare L. (0.5%), and Urtica dioica L. (leaf) (2.5%)—heavier by 207%, 206%, and 205%, respectively. Most of biostimulants increased the content of pigments involved in photosynthesis (e.g. 156% more chlorophyll for 0.1% Hypericum perforatum L. extract), decreased the content of polyphenols (e.g. 47% less for 2.5% Trifolium pretense extract), and showed a varied impact on antioxidant activity. There is an increasing interest in botanical extracts due to their high content of biologically active compounds and wide variety of application possibilities.

In the present paper, products obtained from a blue-green microalga Spirulina platensis filtrate (applied for seed soaking and for foliar spray) and homogenate (used for seed coating) were tested in the cultivation of radish. Their effect on length, wet mass, multielemental composition and the greenness index of the radish leaves was examined. Multi-elemental analyses of the algal products, and radish were also performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). The best soaking time, concentrations of filtrate and doses of homogenate were established. The longest and heaviest plants were observed for homogenate applied at a dose of 300 µL per 1.5 g of seeds and 15% of filtrate applied as foliar spray. The highest chlorophyll content was found in the group treated with 100 µL of homogenate and 5% of filtrate. In the case of soaking time, the longest plants were in the group where seeds were soaked for 6 h, but the heaviest and greenest were after soaking for 48 h. The applied algal products increased the content of elements in seedlings. Obtained results proved that algal extracts have high potential to be applied in modern horticulture and agriculture. The use of Spirulina -based products is consistent with the idea of sustainable agriculture that could help to ensure production of sufficient human food to meet the needs of rising population and protection of the environment.

Plants due to the high content of various bioactive compounds are the main raw material for production of valuable, and useful bio-products (e.g., food, cosmetics, medicines, biostimulants, biopesticides, and feed). Different plant parts, for instance: seeds, fruits, flowers, stems, leaves, and roots can be used for their manufacture. Nowadays, there is a clear need to develop new, efficient, and environmentally safe methods of stimulation of plant, growth and crop protection. Plant-based extracts are new, natural, and multi-compounds products that could be used for these purposes. They possess antifungal, antimicrobial, antiparasitic, antiprotozoal, antioxidant, medicinal, aromatic, and anti-inflammatory properties. This group of natural products has the potential to become a new generation of bio-products suitable for use in sustainable agriculture. The purpose of this review is to provide an overview of the literature describing the impact of plant-derived extracts/biostimulants (PDBs) on crops grown in controlled, and real conditions as well as under various abiotic and biotic stresses; the extraction methods used to obtain PDBs, and the specific constituents responsible for their biostimulating activity. The application of these bio-products could be beneficial for sustainable production, due to several advantages, such as low toxicity to humans and the environment, enhanced resistance of cultivated plants to biotic and abiotic stress, increased yields and quality of crops, as well as the reduction in the use of mineral fertilisers and pesticides. However, deeper cooperation between industrial and academic research is required to accelerate the development of new environmentally safe solutions for future agriculture. Highlights - Higher plants constitute a rich source of various bioactive compounds for the production of useful natural products. - The importance of the proper choice of extraction method and solvent to process and preserve the desired substances.- Plant extracts as biostimulants and plant protection products for use in modern and sustainable agriculture. - The positive effects of plant-based extracts on plants cultivated under normal and unfavourable conditions.- Plant extracts as a new generation of eco-friendly products for the increment of the production of high-quality food.