Productivity of winter wheat varieties depending on sowing time in conditions of the Udmurt Republic

Winter wheat is a crop with the highest biological yield potential among other cereals. However, its cultivation in the Udmurt Republic is considered risky due to the unstable overwintering by years. One of the decisive factors for a successful overwintering of this crop is the optimum sowing time. In connection with the general climate warming in the region, an increase in the period of fall vegetation of plants the adjustment of sowing time is actual. Field studies were conducted in the Udmurt Agricultural Research Institute on sod-podzolic medium loamy soil in years contrasting on meteorological conditions (2013-2016). The object of research was winter wheat varieties: Moskovskaya 39 (standard), Italmas, Mera; Sowing time: August 23-25 (control), August 28-30, September 3-5, September 8-10. According to the results of the research, it was revealed that Mera variety is characterized by a higher winter hardiness compared with Moskovskaya 39 variety. On average over the years of research, its overwintering was 62%, which ensured the highest grain yield - 2.73 t / ha that is 0.52 t / ha higher the standard. The overwintering (54%) and productivity (2.15 t / ha) of Italmas was at the standard level. At sowing in the first (control) and the second time the overwintering of winter wheat varieties was 63% in average, the grain yield was 3.37 and 3.33 t / ha. The decrease was observed in overwintering at sowing at a later date compared with control on 8 and 21%, and grain yield - on 0.44 and 1.96 t / ha