Effect of growth regulators on tomato seed germination and seedling growth

This study analyzes the effects of plant growth biostimulants on seed germination and seedling growth of tomato (Lycopersicon esculentum) cultivars De Barao Yellow and Kibits, which are suitable for organic cultivation due to their tolerance to late blight. The effectiveness of Ukrainian growth regulators – Biolan, Stimpo, Alostim, Regoplant, and Potassium Humate – was evaluated at various concentrations to enhance seed germination rate, seedling vigor, and root system development. The studies were conducted in laboratory conditions using the biotest method.It was found that on the fourth day of seed germination of tomato variety De Barao Yellow, treatment with Biolan at a concentration of 10−3 % increased the length of the roots by 29 % compared to the control, and on the eighth day this same concentration stimulated the growth of the root system by 86%. Similarly, the hypocotyl length increased by an average of 44–49 %, which may contribute to the faster appearance of cotyledon leaves above the soil surfaceand faster plant germination.On the 4th day of germination of tomato seeds of the Kibits variety under the influence of different concentrations of the growth regulators Stimpo, Alostim, Regoplant and Potassium Humate, it was found that almost all the studied growth regulators in most concentrations increase the germination energy. While in the control an average of 82 % of seeds germinated, in the variant of treatment with Alostim at a concentration of 10−3 %–94 %. In relation to the control, the germination energy under the action of Alostim at a concentration of 10−3 % increases by 12 %; with Alostim, Ukrainian humates and Regoplant at a concentration of 10−4 %–11 %; Alostim at a concentration of 10−5 %, Ukrainian humates and Regoplant at a concentration of 10⁻³ % – 10 % more than in the control. There is no increase in germination energy under the influence of too high concentrations of growth regulators such as Stimpo, Regoplant and Potassium Humate at a concentration of 0.1 %. Therefore, the selection of optimal concentrations is very important. The length of the roots also increases. The best results were obtained when treating with Alostim at concentrations of 10−3 % and 10−4 %, as well as Regoplant at concentrations of 10−1 % and 10−4 %, which provided a significant increase in the length of the root system, by 72–81 % more compared to the control.The results obtained confirm that the use of growth biostimulants improves the morphometric indicators of tomato seedlings, contributing to a more active development of the root system. This ensures better adaptation of plants to stressful conditions, in particular drought, by increasing the efficiency of water and nutrient absorption. Growth regulators can be an effective means of improving the quality of tomato seedlings in regions with limited waterresources.