Lazurit winter wheat seeding rates in dependence to the predecessors and time of sowing in the Rostov region

The study is aimed at determining the optimal seeding rates for durum winter wheat Lazurit variety by various seeding dates that would provide the highest grain yield in the conditions of Rostov region. The research was carried out in 2016-2018 on ordinary chernozem after different predecessors for winter wheat (black fallow and sunflower). Studied were: the seeding rates (3 mln, 4 mln, 5 mln viable seeds per hectare after the black fallow predecessor; 5 mln, 6 mln ,7 mln viable seeds per hectare after the sunflower predecessor), and the sowing date (the 10th,20th,30th of September, the10th of October). It has been established that after the black fallow predecessor the seeding rate for durum winter wheat Lazurit variety can be reduced to 3 million viable seeds/ha on the early sowing date (September,10) and optimal sowing date (September, 20). When sowing at the end of optimal (September, 30) and acceptable (October,10) periods, the sowing rate must be 5 million viable seeds/ha. After the sunflower predecessor, on the early sowing date (September,10) and optimal sowing dates (September, 20 and 30) the sowing rate of 5 million viable seeds/ha should be used. At the end of acceptable periods (October,10) the sowing rate should be increased to 6 million viable seeds/ha. After the black fallow predecessor, the highest yield of durum winter wheat has been formed – from 4.61 to 6.06 t/ha depending on the sowing rate and time of sowing. After the sunflower predecessor the yield level ranged from 3.43 to 4.28 t/ha. The optimal sowing time for durum winter wheat Lazurit variety in the south of Rostov region has been established - from the 10th to the 30th of September. Sowing in this period provided the largest number of productive stems (after the black fallow predecessor – 476-568 pcs/m 2 , after the sunflower predecessor – 420-512 pcs/m 2 ), the grain mass per ear (1.21-1.36g and 0.91-1.08g), the plant height (95-100 cm and 92-100 cm), the ear length (6 cm and 4-5 cm, respectively). Conflict of interest: the author stated that there was no conflict of interest.