Effects of Biostimulants in Horticulture, with Emphasis on Ornamental Plant Production

The biostimulant segment is becoming increasingly important worldwide. One of the reasons for this is that fewer plant protection products are placed on the market in the European Union, and environmental sustainability also plays an important role in their use. Biostimulants are often used in several horticultural sectors, including ornamentals, to strengthen plants, achieve commercial standards, produce quality goods, increase plant vitality, and aid harvesting. This paper presents the latest results of the use of biostimulants in horticulture, with special emphasis on ornamental plant production. The legal regulation of biostimulants and their regulatory mechanisms are described in detail in the review. The main groups of biostimulants are also discussed. The response of plants to abiotic stress, in particular physiological, anatomical, and genetic changes, with regard to the application of biostimulants is also detailed. Focus is given to the areas of ornamental crop production, such as sexual and asexual propagation, cultivation, and harvesting, where biostimulants are used.