Influence of sowing dates and plant density on sunflower yield in the Right-bank Steppe of Ukraine

Abstract

Actuality. In order to increase the gross collections of sunflower seeds and increase its productivity, the best place for sowing and planting density, which in different soil-climatic zones are not identical and fall under different calendar dates, occupy the leading place. At the same time, there is no consensus on the optimal timing of planting and planting density. Analysis of recent researches and publications. ON. Pleshakov, VS Pustovoit believe that sunflower is an early-sowing crop due to its biological characteristics, on the one hand, and extraordinary sensitivity, even to minor autumn frosts during maturation, on the other. The authors argue that sunflower seeds can sprout at a temperature of 4-5°C, while stairs can withstand short-term spring frosts - minus 4-6°C.  The passage of the sunflower phase of growth and development in optimal terms contributes to better use of autumn-winter-early spring soil moisture reserves, reduces the probability of falling into development and maturation stages in unfavorable conditions. Plant density is one of the main factors that determines the efficiency of fertility use, temperature and water regimes of soil, solar energy and other components of livelihoods of agrocenosis. This indicator depends both on climatic conditions and on the genotype of the hybrid, and in the conditions of the Ukrainian Steppe ranges from 40 to 70 thousand plants per hectare. The choice of the optimal time of sowing and plant density is a prerequisite for the effective use of environment resources for the formation of high crop yields. The materials and methods for investigation. The research was conducted during 2016-2017 at the Kirovohrad State Agricultural Research Station of the National Academy of Agrarian Sciences of Ukraine (KSSGDS NAAS) in order to
increase productivity by improving the terms of sowing and density of sunflower plants in the conditions of the Right Bank Ukraine. In a three-factor field experiment, the following factors were investigated: Factor A - medium sunflower hybrids Sunflower Forward, LG 56.32, LG 54.85, LG 5582; Factor B - Early lines of sowing (I - for soil temperature at a depth of 10 cm - 5-6 ° C, II - 7-8 ° C, III - 9-10 ° C); Factor C - plant density 50 thousand /ha, 60 thousand/ha, 70 thousand / ha. The repetition of the experiment is three-fold, the total area of the sowing area is 50.4 m2, accounting -25.2 m2. Predecessor-spring barley. The main abatement of the soil is the black earth, the ordinary transition to deep. Granulometric composition - heavy-grained. Characterized by the following agrochemical indicators: in the arable layer, on average, contains humus of 4.72%, easily hydrolyzed nitrogen - 104, mobile phosphorus - 191 and exchangeable potassium - 142 mg per kilogram of soil, mobile manganese, zinc and boron forms - respectively 3 , 1; 0.35 and 1.76 mg per kilogram of soil. Reaction of soil solution of pH of salt - 5,8. Soil conditions are favorable for the cultivation of sunflower. The results and discussion. The conducted studies allowed to establish that the shift of sowing dates at earlier times affected the growth and development of plants accordingly. Depending on the timing of the sowing and the temperature regime, the level of supply of productive moisture, the duration of the vegetation period and the overall yield were changed. On average, over the years of research, the duration of the period of the sowing-seedlings depended on the temperature regime and the productive moisture reserves in the seed layer of soil 0-10 cm. The moisture reserves were sufficient to obtain complete stairs and were at the time of the first sowing time of 25.2 mm, the second 24.5 mm, the third 24.0 mm. At the same time, the duration of the period of the sowing - the stairs for the first period of sowing was 18 days, the second seeding period - 17 days and the third seeding period - 12 days. Analyzing the results of the research it should be noted that in most cases, a larger seed yield in sunflower hybrids was formed in those variants where the period from the formation of the basket until the flowering occurred in June or the first
decade of July, regardless of the year of the test, exactly when precipitation is possible for middle-aged indicators. On average, over the years of research, the highest yield in the first year of sowing was: for the hybrid Forward 2,86 t/ha for a density of 50 thousand, a hybrid LG 56.32 – 3,12 t/ha with a density of 70 thousand, hybrids LG 54.85 and 55.82 - 3,59 and 3,65 t / hectare with a density of 60 thousand, with the second seed line for the hybrid Forward 3,07 t/ha for a density of 50 thousand, a hybrid LG 56.32 – 3,55 t/ha by density 60 thousand. LG hybrids 54.85 and 55.82 – 3,66 and 3,68 t/ha by density 60 thousand, with the third line of sowing for the hybrid Forward 3,05 t/ha with a density of 60 thousand, LG hybrid 56.32 - 3.53 t/ha for density of 70 thousand, hybrids LG 54.85 and 55.82 - 3.61 t/ha per density and 60 thousand and hybrids LG 55.82 3,48 t/ha. Conclusions. Taking into account the annual variation of the weather conditions of the spring period from the average annual parameters, due to the shift of the sowing terms, it is possible to change the conditions for the growth and development of plants of sunflower, that is, to avoid the critical period of development of plants. The choice of sowing terms for sunflower hybrids should be based on the temperature of the soil warming at the depth of the seeding, and not on the calendar, as in each growing zone, these terms will vary substantially. In the conditions of the Right Bank Ukraine, on average, over the years of research, the hybrid Forward showed higher yields for the second seed stage – 3,07 t/ha and plant density - 50 thousand/ha; the LG 56.32 hybrid showed higher yields for the second seeding period – 3,55 t/ha and density of plants – 60 thousand/ha, the hybrid LG 5582 showed higher yields for the first and second seedlings – 3,65 and 3,68 t/ha, while the LG hybrid 54.85 produced higher yields for the second and third sowing periods – 3,66 and 3,61 t/ha. and the density of plants - 60 thousand/ha. Consequently, high sunflower requirements for environmental resources do not exclude early seeding, but, on the contrary, confirm the relevance of research into their effectiveness.