Productivity and elements of the formation of the structure of the yield of sunflower genotypes when treated with plant growth regulators
Authors: Chuiko D.V. 
Published: March 2021

Formulation of the problem. Among the main opportunities for improving seed production and the technology of growing sunflower in general is the use of plant growth regulators (further – PGRs). The main problem of PGRs is their strong dependence on weather conditions during the processing of plants. In addition, with the rapid increase in the number of PGRs in the State Register of Pesticides and Agrochemicals, their effect on various types of genotypes and their functionality under uncontrolled weather conditions remains poorly understood.
Relevance of the topic. One of the most cost-effective and proven effective is the use of plant growth regulators. To date, a whole series of synthetic growth regulators, which in its composition has the active substances of humic origin, mineral compounds and extracts with different plants. But today the reaction of each genotype of sunflower separately from each other under the action of PGRs with different active substances remains little studied.
Purpose. Study of the response of various genotypes of lines, hybrids and varieties of sunflower to the use of plant growth regulators.
Material and methods. The studies were carried out in the period from 2018–2020., on the experimental field of the Department of Genetics, Breeding and Seed Production of KhNAU named after V.V. Dokuchaev. Lines, experimental hybrids and varieties of sunflower were used as the studied genotypes. Plant growth regulators Fulvital Plus, EcoStim, QuadroStim and applied by spraying during the growing season in the phase of 2–5 true leaves, and again in the phase of the sprocket.
Conclusions. On average, over the years of research, the productivity of sterile lines increased from 0.7 to 38.1 %, depending on the PGRs and genotype. It is noted that lines SKh808A and SKh1002A have a greater potential to increase the structural indicators of the yield. One of the factors is their high adaptive capacity to the environment. The average rate of increase in line productivity according to PGRs from 5.1 g formed in the SKh1002A line and in SKh808A by 7.1 g. The weight of 1000 seeds increased from 0.3 to 24.7 % depending on PGRs, natural seeds and was within from -3.7 to 17.3 % depending on the drug and the line.
The influence of PGRs on fertile lines of sunflower was weaker in comparison with sterile lines. By factor B, an increase in productivity was noted in the Kh785V line by 15.8 % and in the Kh1012B line by 27.7%, respectively. The main influence of PGRs in these lines under study was an increase in the mass of 1000 seeds. Thus, this indicator was 44.4 g for the Kh1012B line, which is 30.3 % more than the control and in the Kh06135V line – 53.1 g, an increase of 15.3 % to the control. The low performance of fertile lines compared to sterile lines is a consequence of the energy consumption of plants, since fertile lines produce pollen during the growing season, while fertile lines spend only energy on seed formation.
The use of PGRs turned out to be quite effective in experimental hybrids. An increase in the genetic set occurs precisely during the creation of hybrids, the manifestation of heterosis increases the productive and adaptive capabilities of plants. The increase in the productivity of the hybrids was in the range of 0.3–19.6 %, the mass of 1000 seeds was in the range of 3.4–16.7 %.
The productive characteristics of sunflower varieties had a low response to the use of PGRs Fulvital Plus, EcoStim and QuadroStim during the research period 2018–2020.
Keywords. seed production, breeding, lines, sunflower, plant growth regulators, yield, hybrids, variety.