Management of productivity of sunflower plants depending on terms of sowing and density of standing in arid conditions of the Right-bank Steppe of Ukraine

Abstract

The article presents the results of scientific research conducted in 2016–2018, in order to determine the impact of sowing dates and standing density on the growth, development and productivity of sunflower hybrids. The field experiment was performed by the method of splitting plots in three replications in the experimental field of the Institute of Agriculture of the Steppe of NAAS in arid conditions of the Right Bank Steppe of Ukraine. The material for the study were sunflower hybrids of the middle-early maturity group – Forward, LG 56.32, LG 54.85, LG 5582 (Factor A); terms of sowing – the first when warming up the soil at a depth of seed wrapping to 5–6°C, the second when warming up the soil at a depth of seed wrapping to 7–8°C, the third when warming up the soil at a depth of seed wrapping to 9–10°C (Factor B); density of standing plants – 50, 60, 70 thousand per hectare (Factor C).Research found that the productivity of sunflower plants directly depends on the temperature of the soil (sowing dates), optimal water regime, density of standing plants, genetic and morphological characteristics of hybrids. It is also established that by regulating timing of sowing and selecting the optimal density of standing plants can affect the growth and development of sunflower plants, bypassing critical periods during cultivation. The optimal time for sowing sunflower for hybrids LG 55.82 and LG 54.85 is warming the soil at depth of seed wrapping up to 5–6°C, for hybrids Forward and LG 56.32 is warming the soil at a depth of seed wrapping up to 9–10°C. On average, according to the years of research, the highest seed yield of 3.85 t ha–1 was formed by the hybrid LG 55.82, which is higher than that of the hybrids Forward, LG 54.85 and LG 56.32 by 19.8%; 5.5% and 6.0%, respectively. It is established that the optimal density of sunflower is 60 thousand plants per hectare. Thus, sunflower productivity varied significantly under the influence of the morphobiological features of the hybrid – factor A (the proportion of impact was 47.5%), density of standing plants (factor C) – 5.4%, sowing time (factor B) – 3.4%.