When growing sunflower in the southern steppe of Ukraine, the main limiting factor is moisture. The amount of water consumed and the intensity of its consumption by plants depends on environmental factors and biological characteristics of sunflower. Therefore, it is important to ensure the rational use of available moisture in the soil by crop plants.
The aim of our research was to establish the impact of sowing dates, application of soil herbicide and crop care methods on water consumption and productivity of sunflower hybrid Region in the southern steppe of Ukraine.
The research was conducted in 2011-2013 in the fields of the Institute of Oilseeds of UAAS. The sunflower of the Region hybrid was sown with a row spacing of 70 cm and a sowing rate of 50,000 similar seeds per hectare in three terms: the first (I) – at a soil temperature of 6-8 °С; the second (II) – at a soil temperature of 10-12 °C; third (III) – at a soil temperature of 14-16 °C. Variants of crop care methods: 1 – before and post-emergence harrowing + 1 inter-row tillage; 2 – pre-emergence harrowing + 2 interrow cultivation; 3 – 2 inter-row treatments on herbicide and herbicide (application of soil herbicide harnes – 2.5 l/ha under pre-sowing cultivation) backgrounds.
According to the results of three years of research, it was found that the timing of sowing and different methods of crop care on herbicide and non-herbicide backgrounds affected the water consumption and productivity of sunflower hybrid Region.
Depending on the sowing period, the total moisture reserves in the soil layer 0-150 cm at the beginning of the growing season were equal to: 420.9 mm for the first; 410.3 mm for the other; 385.0 mm for the third. The amount of precipitation, taking into account the utilization factor for three years on average, was equal to: 150.9, 147.9 and 148.5 mm, respectively. Given the moisture reserves at the beginning of the growing season and productive precipitation, the total water consumption of sunflower hybrid Region was different in terms of sowing and was depending on the application of the herbicide and crop care: for the first – 301.0-316.3 mm; for the other – 292.6-301.0 mm; for the third – 263.1-278.2 mm. Sowing at a later date led to a decrease in total water consumption of sunflower by 8.4-17.3 mm in the second term and 37.9-43.6 mm in the third term compared to the first. For three sowing dates on both herbicide and herbicide-free backgrounds, the lowest total water consumption was observed in the variant with pre- and post-emergence harrowing and one inter-row tillage.
According to the results of average three-year studies, moisture was most effectively used by sunflower plants of the Region hybrid in second-term crops, ie water consumption coefficients were lower (1207-1229 m3/t). During the first and third sowing periods, they increased in accordance with 1550-1628 and 1302-1331 m3/t, respectively. Regarding the backgrounds of herbicide application, during the first and second sowing periods, moisture was used more effectively against the background of soil herbicide application. And for the third sowing period, on the contrary, the coefficient was lower by 15-18 m3/t on a herbicide-free background. The lowest indicators of the water consumption coefficient were observed during the second sowing period against the background of soil herbicide application in the variants with pre-emergence harrowing + 2 inter-row treatments (1209 m3/t) and two inter-row treatments (1207 m3/t).
On average, over three years of research, depending on the background of herbicide application and crop care, higher yields of sunflower hybrid Region (2.38-2.49 t/ha) were obtained during the second sowing period, which is 0.44-0, 52 and 0.35-0.43 t/ha exceeded this figure for the first and third terms, respectively. It should be noted that the most effective application of soil herbicide was during the first sowing period, the yield increase was 0.10-0.12 t/ha. During the second sowing period, it was lower – 0.06-0.07 t/ha. In the absence of weeds in the third sowing period, the application of soil herbicide was not effective. The increase in yield (0.01-0.03 t/ha) was within the NIR. Among the methods of crop care, the most effective options were: pre-harvest harrowing + 2 inter-row tillage and 2 inter-row tillage. The highest yield of sunflower hybrid Region (2.49 t/ha) was obtained during the second sowing period at the soil temperature at the depth of seed wrapping 10-12 °C with the application of soil herbicide and pre-emergence harrowing and two inter-row tillage.
According to the results of the fat content in the seeds, the influence of agricultural techniques studied in the experiment was not observed. For the first term of sowing the fat content was 46.6-46.8 %, for the second term - 46.1-46.4 % and for the third term – 46.2-46.3 %. An important indicator of sunflower productivity is the yield of oil per unit area. According to the results of research, depending on the yield obtained under the influence of the background of herbicide application and crop care, higher oil yields (966-1017 kg/ha) were observed during the second sowing period, which is 173-203 and 143-179 kg/ha exceeded this figure for the first and third terms, respectively. The highest oil yields were observed during the second sowing period against the background of soil herbicide application in the variants with pre-emergence harrowing + 2 inter-row tillage (1017 kg/ha) and two inter-row tillage (1010 kg/ha).
Total water consumption of cereals on the slopes of the Central District of Russia and zoned bioclimatic ratios
