Aim. The goal of this research was to determine the infl uence of AKM plant growth regulator on the perfor- mance of large-seed Lakomka sunfl ower variety, sowing and yielding properties of seeds. Methods. Agro- chemical and biometric methods. Mathematical analysis of the results was carried out by Student’s test and licensed Agrostat computer program. Results. The results of the study on the impact of AKM plant growth regulator (PGR) on growth, development and yield formation of sunfl ower in low moisture conditions of Southern Steppe of Ukraine are presented. Pre-sowing seed treatment of Lakomka sunfl ower variety with AKM plant growth regulator causes an increase in leaf surface area by 22 %; pollen fertility – by 27 %; reduces the phenological phases by 2−4 days on average, increases the resistance of sunfl ower plants to abiotic stress and increases yield by 26 %. It is proven that the proportion of the impact of water stress of the studied year (58.4 %) is signifi cantly higher than that of the impact of PGR (32.7 %). Conclusions. AKM plant growth regulator is recommended for the use on sunfl ower in 0.015 g/l concentration.

Extremely uneven distribution of moisture during the growing season dramatically increases not only the risk of safflower seeds yield reduction, but its quality as well. One of the main reserves of solving this problem is the dose of fertilizers, particularly nitrogen, and use of plant growth regulators (PGRs) in the critical phases of plant development. It is the optimum combination of these factors that is a significant reserve for increasing yield stability and quality of safflower seeds. The aim of the research was to identify the impact of AKM PGR on productivity of safflower plants at different levels of mineral fertilization. The results of the study on the impact of the AKM plant growth regulator on growth, development and yield formation of safflower in low moisture conditions of Southern Steppe of Ukraine are presented. Optimal concentration of AKM PGR (0.0015 g/l) was determined. Seeds, processed by AKM PGR, had laboratory germination 5.7 % higher than in the control. In 2016, the safflower plant height for all variants was higher than this figure in the other years of the study. This is because HTC in 2016 for the period BBCH 00-39 was higher than in 2015 by 1.4 times. Therefore 1 anthodium formed on average 13.2 to 21.6 seeds. AKM PGR increased, compared to control, both weight of seeds in 1 anthodium, and the number of anthodia during the study years, thanks to antistress properties of AKM. This preparation significantly affected yield only in unfavourable years, and the impact of fertilizers was insignificant. The AKM plant growth regulator is recommended for the use on safflower in 0.0015 g/l concentration.

The intensity of lipid peroxidation of caryopsis, roots and sprouts of winter wheat and its effect on seed germination and seedling growth were studied. Two years of seed storage decrease its vitality, adversely affecting germination qualities. Sterilization of seeds causes an additional chemical stress, which can be regulated by plant growth regulators (PGR) with antioxidant properties. Anti-stress PGRs are able to reduce the negative impact of prolonged oxidative stress caused by protectants and chemicals during sterilization, especially during heterotrophic type of nutrition. Adaptation of primary roots and sprouts to the conditions of caryopsis germination proceeds differently. In roots it ends with transition to autotrophic nutrition, and sprouts-goes to the stage of formation of the first unfolded leaf regardless of the effect of investigated stress factors. In general, the intensity of oxidative stress in sprouts is double as that in the roots. A strong inverse correlation dependence (r =-0.908 ÷-0.997) was determined between malondialdehyde (MDA) and dry matter content in the roots, which should be considered when choosing a combination of protectants and PGR.