In recent decades, humanity has faced the main problem of the planet, global climate change. This problem is primarily accompanied by an elevated temperature regime, which disrupts the processes of water circulation, and its “new” redistribution. As a result, in some regions, huge volumes of moisture evaporate and droughts intensify, while in other regions this moisture condenses, and there are more frequent showers, floods and storms.
The continental climate zone covers most of the territory of Ukraine. However, now it is significantly decreasing in size every year, giving way to a dry climate zone, which is common only in the south of the country.
According to meteorological observations, the number of days with high daytime air temperatures (above 30°C) doubled in all regions of Ukraine, and the duration of the vegetation period of crops increased by an average of 10 days. By 2030, the period of growth and development of heat-loving crops is likely to be extended by another 10 days. The Polissia and Forest-Steppe zones are warming faster than the steppe regions. The climatic conditions of the southern Steppe will have modern features of dry subtropics. It’s only a matter of time.
Over the past 10 years of sunflower cultivation, its area as a highly profitable oil crop has increased from 3.5 million hectares to 6.3 million hectares. And the yield potential on average in Ukraine for these years is from 16 to 26 t/ha. And as a result, the volume of gross production increased from 5.7 million tons to a record 15 million tons already by 2019.
The world market and demand for sunflower products encourages the farmer to focus his production on this crop. Despite all the difficulties that stand on the way to obtaining a high sustainable harvest, farms install cost-effective irrigation systems, change traditional technologies to more rational or intensive ones, test many methods and elements in the technological process, for example, from the selection of a hybrid to the selection and assembly of agricultural machinery. Almost scientific activity begins in the fields of every economy, which does not stand still in development. Farmers are constantly experimenting with the main goal of obtaining a high, stable and high-quality harvest of oilseeds.
How does effective sunflower cultivation begin?
Reasonable predecessor. Winter wheat or winter barley is the best predecessor for sunflower in arid conditions. After harvesting this precursor, plant remains are crushed and evenly distributed on the surface of the soil, creating a kind of mulch. This makes it possible to weaken surface heating, reduce evaporation from deeper layers, better accumulate and distribute the moisture that comes with precipitation on the surface.
Reasonable choice of hybrid and weed protection technology. The sunflower seed market is very saturated today, and each growing area has its own hybrid or assortment of hybrids.
And among this assortment there are sunflower hybrids of Serbian selection, which are produced by the company “Evrosem”. Such hybrids as Tor , Avalon , Pegas , Sumo Novo , Sumo 007 were classified as the most drought-resistant .
Cultivation of each of these hybrids has its advantages in difficult drought conditions.
- First, these hybrids have a low transpiration coefficient of 400-450, which means that such plants use less moisture to form a unit of dry matter.
- Secondly, hybrids have a wide specialization depending on what protection technology the farmer uses. That is, all of the listed hybrids can be grown according to the classic technology of protecting crops from weeds, only Tor and Avalon are limited to growing according to the classic technology, and Pegasus can be grown both according to the classic technology (Kirovohrad region, Dnipropetrovsk region) and according to the technology “Clearfield” (a synonym for “Eurolightning”). Hybrids Sumo Novo and Sumo 007 can also be grown according to classical technology without the use of a special herbicide (Donetsk region, Vinnytsia region), but most farms grow according to the technology characteristic of these hybrids – “Express Sun” (synonymous with “granstar”, under “express”, under “sulfo”).
- Thirdly, hybrids have genetic signs of resistance to the main enemy of sunflower plants – the sunflower beetle. However, resistance to race H and race G is still closely intertwined with resistance to long-term moisture deficit. On the other hand, plants that are affected by lupus very early are “stressed” – they are suppressed by the parasite, cannot withstand the lack of nutrients and moisture, as a result of which they die.
Basic tillage or soil preparation for sowing. The main cultivation of the soil is an important stage for ensuring sustainable production, and at the same time, the accumulation and conservation of moisture in early spring is no less important. Therefore, plowing, deep loosening, Strip-Till (strip deep cultivation) or No-Till (minimum tillage) are used today in arid conditions.
Each of these types of tillage has its own time, conditions and recommended hybrid. If plowing is carried out up to 30 cm (Odesa, Mykolaiv, Kherson, Zaporizhia regions) or loosening up to 30 cm (Mykolaiv, Zaporizhia, Dnipropetrovsk regions), then, as a rule, any hybrid is sown. For Strip-Till (Mykolaiv, Dnipropetrovsk, Poltava, Cherkasy, Kirovohrad region) hybrids Pegas, Thor, Avalon, Sumo Novo, Sumo 007 are better suited, for No-Till (Odesa, Mykolaiv, Zaporizhzhya, Dnipropetrovsk, Poltava, Kharkiv, Cherkassy region) – Thor, Sumo 007, Pegasus.
Sowing and sowing dates. There are two solutions for sowing sunflower in arid conditions. The first is the early sowing of hybrids, which are also cold-resistant. This solution is used by farms with the material and technical base for classical soil cultivation (plows, disc harrows, cultivators). The second solution is sowing with direct seeding multi-complex planters such as Kuhn, Horsch, Kverneland, Great Plains, John Deere, Mzuri, etc.
The task of this technique is to perform all the sowing processes in one pass. At the same time, another positive point is that the consumption of resources and time is reduced, more moisture is stored in the upper layer of the soil, and the mechanical pressure on the soil is lower.
Based on the experience of successful sunflower cultivation in 2020, the optimal sowing dates for Eurosem hybrids in the following arid regions were determined:
- Zaporizhzhia – April 16-April 26,
- Dnipropetrovsk – May 7-May 17,
- Mykolayivska – April 17-April 27,
- Donetsk – May 5-May 15,
- Kherson – April 5-April 15,
- Odesa – April 10-April 20,
- Kirovohradsk – April 30-May 10.
With early sowing in insufficiently warmed soil, the energy and field germination of seeds decreases. On the other hand, sowing in overheated soil also leads to loss of seeds during the germination stages, so sowing should be carried out at a time when the soil temperature at a depth of 5-7 cm is within 8-9°С.
The sowing depth for hybrids with large seeds (weight of 1000 seeds from 65 g) is 6-7 cm, and for medium and small ones (weight of 1000 seeds from 50 to 65 g) is 4-5 cm.
In conditions of unstable and insufficient moisture, the wrong selection of density leads to to a decrease in yield up to 50%, and in dry conditions up to 100%. Therefore, the density of sunflower crops of Serbian selection in arid conditions should be in the range from a minimum of 35-45 thousand plants/ha (south of Odesa, Kherson, Mykolaiv, Zaporizhzhya regions) to 45-55 thousand plants/ha (north of Odesa, Donetsk, Zaporizhzhya, Dnipropetrovsk, Mykolaiv, Kirovohrad, Cherkasy regions).
The width of the row spacing during sowing is classically 70 cm, but in drought conditions of farms with a high level of technological support, they are sown to a width of 35 cm, 56 cm. Such placement schemes are optimal for ensuring the proper conditions for the development of productive stems, plants early shade the soil surface, which prevents intensive moisture loss during evaporation. Hybrids that are suitable for sowing with narrowed spacing are Sumo Novo, Sumo 007 and Avalon.
Feeding and fertilizing sunflower in arid conditions begins with the introduction of ammonium sulfate 100 kg/ha or ammophos 150 kg/ha in the fall under the main soil treatment, and KAS 150 kg/ha is applied during the spring closing of moisture or pre-sowing cultivation. Hybrids Sumo 007 and Pegas respond perfectly to the application of fertilizers in the row. For post-sowing application, it is advisable to use sulfoamofos 80 kg/ha or nitroamofoska 80 kg/ha. Leaf top dressing is preferably carried out until the row spacing is completely closed with water-soluble fertilizers in the form of potassium humates 1.5-2.0 l/ha, magnesium sulfate 3-5 kg/ha, urea 10 kg/ha, boron fertilizer in the form of a 10% boron solution – 1.0 l/ha.
In the fight against weeds, it should be understood that most types of weeds in arid conditions have higher moisture consumption needs and are able to create significant competition for sunflower plants. The main weeds in arid conditions with a high transpiration coefficient are ragweed, common nettle, bitter gorse, field birch, pink thistle, white quinoa, black nightshade. Flurochloridone or metobromuron (Proman) is better suited to combat ragweed and other resistant dicotyledons before emergence, and post-emergence application of glauxifen-methyl (Heliantex) for the final cleaning of crops. To ensure timely control in crops of “Eurolightning” hybrids Pegasus and Griffon, the drug is applied early in phase 2 of true leaves of the crop. Inter-row cultivation is carried out only in crops of classic Avalon and Tor hybrids before the leaves begin to close in the inter-rows, for Sumo 007 and Sumo Novo hybrids, as a rule, one inter-row cultivation is enough if there is a need for it.
In arid conditions, the estimated time for harvesting sunflowers can be reduced by 10-25 days, and in the conditions of the Northern Steppe, on the contrary, it can be increased. But they can be set according to the principle of the length of the period from the moment the plants bloom. For hybrids Thor and Avalon, it is 47-53 days, Pegasus – 52-57, Griffon – 49-53, Sumo 007 – 50-55, Sumo Novo 55-60 days. It should also be taken into account that hybrids in arid conditions can retain seed moisture in different ways and ripen differently, so it is advisable to measure seed moisture 5-7 days before the end of the harvest period.
Therefore, if all technologies are followed and environmental factors are taken into account, it is possible to obtain a consistently high yield even in arid regions.