Analysis of the Effectiveness of Biological Plant Protection on Sunflower Productivity under Different Cenosis Density under the Non-Irrigated Conditions of the Steppe Zone

Abstract

The field experiments were conducted in 2021-2022 on the experimental field of the Mykolaiv State Agricultural Research Station of The Institute of Climate-Smart Agriculture of The National Academy of Agrarian Sciences of Ukraine under non-irrigated conditions on southern chernozem. The humus content in the arable soil layer is 2.90%, the depth of the humus layer is 0-30 cm, and the transitional layer is 30-60 cm. The research was conducted by establishing a three-factor field experiment, where factor A is sunflower hybrids of the Plant Production Institute named after V.Ya. Yuriev of National Academy of Agrarian Sciences of Ukraine - Vyrii, Yarylo, Blysk, Yaskravy and Epikur; factor B - different plant densities (30, 40 and 50 thousand/ha) and factor C - treatment of vegetative plants in the phase of budding with substances of biological origin (Helafit Combi, Organic Balance and Biocomplex BTU). The field experiment is located on the winter wheat forecrop. Fertilizers were applied during the main cultivation at a dose of N30P30K30. Sowing is carried out with a row spacing of 70 cm in the last decade of April. Yield accounting and the evaluation of the crop structure were carried out by manual threshing of plants selected from the accounting area of the test plots and recalculation by 8% seed moisture. From the results of observations, it was found that foliar treatments of sunflowers with environmentally friendly combined-action substances contributed to the prolongation of the interphase periods in the second half of the growing season of all studied hybrids. Treatment of plants with environmentally friendly substances helped to reduce the level of damage to all hybrids by pathogenic microflora, the highest fungicidal efficacy was observed in Helafit Combi and Organic Balance. All hybrids formed the highest yields at a density of 40 thousand units/ha. Dense plantings up to 50 thousand units/ha were inferior in yield to the ones with a planting density of 40 thousand units/ha and were almost at the same level as the ones with 30 thousand units/ha. Hybrids Yarylo, Epikur and Yaskravy were significantly inferior in productivity, however, their foliar treatments also had a similar tendency to increase their productivity.