Weather and climatic conditions determine moisture supply, which is the main factor affecting winter wheat productivity in the area of unstable moisture. The current study was carried out on the experimental plot of the laboratory for cultivation technology of grain crops of the FSBSI Agricultural Research Center “Donskoy” in 2010–2020. The soil of the experimental plot was ordinary calcareous heavy loamy blackearth (chernozem). The humus horizon was powerful up to 140 cm. The humus content was 3.9%. The purpose of the study was to establish the moisture supply of winter bread wheat when cultivated according to various forecrops. There has been found that the autumn periods in the most years of study were arid with 37% of precipitation. Winter wheat plants from September to June were provided with 70% of precipitation, with a 1022.55 of air humidity deficit and 664.7 mm of water demand. There was found that, on average over the years of study, 88% of moisture supply promoted yielding of 7.03 t/ha of winter wheat sown in weedfree fallow. In order to yield a ton of grain there was required 591.7 m3 of total moisture. The share of precipitation in this moisture consumption was 84%, and the share of soil moisture was 16%. When sown after sunflower, moisture provision was 77%, and winter wheat yield was 5.32 t/ha. In order to yield a ton of grain there was required 657.3 m3 of total moisture, which was on 65.6 m3 more than in the variant with a weedfree fallow. The share of precipitation in this moisture consumption was 96%, and the share of soil moisture was 4%.

In the southern zone of Rostov region there were studied seeding rates (1, 2, 3, 4, 5, 6, 7 million pcs/ha) and sowing dates (the 10th, 20th, 30th of September, the 10th of October) of Univer soft winter wheat variety according to various forecrops (black fallow and sunflower). The research was carried out in 2020-2021. It has been established that according to the studied predecessors, the Univer variety shows a tendency to form the highest grain yield in the late sowing periods (September, the 30th and October, the 10th): significantly higher by 0.43-0.73 t/ha in comparison with the control sowing on September, the 20th. It was determined that, regardless of the sowing date, according to the «black fallow» predecessor the maximum productivity of 6.33-7.13 t/ha had been obtained with seeding rates of 4 and 5 million pcs/ha, and 4.16-4.80 t/ha with seeding rates of 6 and 7 million pcs/ha when sown after sunflower. The least productivity but the highest protein and gluten percentage in the variety was identified in the variant with the minimum seeding rate (1 million pcs/ha) and was 5.08-6.09 t/ha sown after the black fallow with 13.7-14.3 and 25.0-26.0 %, respectively; 3.00-3.59 t/ha sown after sunflower with 13.6-14.0 and 22.9-24.3 %, respectively. With a sowing rate increase, high productivity was due to the number of productive stems. When sown after black fallow, the greatest economic effect of Univer variety was obtained when sown on the 10th of September with a seeding rate of 5 million pcs/ha. When sowing in later dates, there was an increase of efficiency of lower seeding rates of 2, 3 and 4 million pcs/ha. When sown after sunflower, there was a high economic effect with seeding rates of 5, 6 and 7 million pcs/ha at all sowing dates.

The current paper has presented the results of the study conducted in the southern part of the Rostov region by the Agricultural Research Center “Donskoy” in 2019–2021. The purpose of the work was to identify how grain productivity and its qualitative indicators of the winter bread wheat variety ‘Yubiley Dona’ are formed under the influ­ence of various sowing dates and after various forecrops and to estimate the economic efficiency of these elements of cultivation technology. There were used such dates in the trial as September 10, September 20, September 30, and October 10; such forecrops as peas (for grain), sunflower, black fallow, green-manured fallow (corn kale). When laying and conducting the trial, there were used conventional methods. The total area of the plots was 55 m2, the accounting area was 41.25 m2, with four-fold repetition. The seeding rate was 5 million germinated seeds per 1 ha. The soil of the experimental plot was ordinary calcareous heavy loamy blackearth (chernozem). The arable layer of the soil contained 3.2 % of humus; 7.0 of pH; 18.5–20.0 of P2O5; 342–360 mg/kg of K2O. The variety ‘Yubiley Dona’ showed its adaptabil­ity to the sowing dates when sown in black fallow. At the same time, there was identified a positive effect of the sowing in black fallow on September 20 and 30, where the productivity level of the variety reached 6.92–6.95 t/ha, and there was obtained the largest conditionally net income of 62058–62732 rubles/ha. There was established that the highest production profitability was 165.3–168.7 % when the variety was sown after peas on September 30 and October 10. There was a high adaptability to the sowing of the variety at the end of the optimal sowing dates in green-manured fallow, after peas and sunflower. The lowest productive profitability was established when the variety was sown after sunflower (135.4–153.4 %) and in green-manured fallow (127.5–139.2 %). The determining factor in the productivity formation was a productive thick stand, which, depending on the forecrops and sowing dates, varied from 452 to 654 pcs/m2. Black fallow, green-manured fallow and peas contributed to the production of high-quality grain.

The current study was carried out on ordinary blackearth (chernozem) in the southern part of the Rostov region in the FSBSI “ARC “Donskoy” (2017–2020 agricultural years). The purpose of the work was to identify the effect of autumn and spring sowing periods on grain productivity and quality of the facultative barley variety ‘Marusya’ according to various forecrops. There has been considered the dynamics of the productivity of the variety ‘Marusya’ depending on the sowing time when sown after maize for grain and sunflower. There has been established high adaptability of the variety ‘Marusya’ after nonfallow forecrops. It has formed a high productivity when sown in autumn at various times. There has been found out a positive reaction of the variety to sowing on September 10, 20 and 30, where the maximum productivity when sown after maize for grain was 6.76–6.91 t/ha. When sowing at later time, there was a slight decrease in productivity. When sown in spring, the highest protein percentage in grain was 11.0 and 11.6%. However, due to the highest productivity, the maximum protein yield was when sowing in autumn, up to 0.71 t/ha. The calculation of the economic efficiency of grain production showed that the highest profitability (214.1 and 214.4%) was obtained when the variety ‘Marusya’ was sown on September 10 and 20 after maize for grain. On average, over the years of study, the maximum conditional net income according to the forecrop, depending on the sowing time, was from 59658 to 84261 rubles/ha when sown in winter and from 48881 to 59170 rubles/ha in spring. The minimum profitability 62.1–75.2% was identified when sown in spring in 10 days after the soil was physically mature.

The current paper has presented the results of study conducted at the Agricultural Research Center “Donskoy” in 2019–2021. The winter bread wheat variety ‘Lidiya’ was taken as the object of study. The forecrop was sunflower. In the variants where it was planned to yield 5.0; 6.0 and 7.0 t/ha, there were used mineral fertilizers (ammonium nitrate, ammophos and potassium salt) in doses (mean through the years) of N66P66K43, N79P79K52 and N92P92K61, respectively. In the control variant, there were used on fertilizers. The purpose of the study was to find out the possibility obtaining the planned winter wheat grain productivity in the southern part of the Rostov region under the use of mineral fertilizers. The amount of precipitation during the agricultural year and a vegetation period of winter wheat was 520.3 and 431.6 mm, while the norm was 582.4 and 446.3 mm, respectively. Depending on the hydrothermal conditions, the sum of air humidity deficits from September to June varied from 1034.1 to 1278.2 mm over the years, and water need for plants ranged from 672.2 to 830.8 mm. The coefficients of precipitation and moisture availability for winter wheat were in the range of 0.53–0.67 over the years. The hydrothermal conditions during the years of study determined win­ter wheat moisture supply during a vegetation period and contributed to obtaining grain productivity of different levels. Under the prevailing hydrothermal conditions, it was not possible to obtain the planned productivity of the winter bread wheat variety ‘Lidiya’. However, all applied doses of mineral fertilizers were cost-effective and there were obtained a significant yield increase of 1.28–2.03 t/ha (the yield on the control was 3.52 t/ha). There has been recommended to take into account the conditions of moisture supply in the cultivation zone when planning productivity and effective use of mineral fertilizers.