The influence of the duration of the growing season on the crop yield and grain size of spring wheat in the Amur region
The article presents the findings of a threeyear study of the influence of the duration of the growing season of spring wheat on the yield and weight of 1000 grains in the southern zone of the Amur region. Studies were carried out on 54 varieties of domestic and foreign selection. It is believed that a longer growing season positively correlates with the crop yield of varieties. Under the conditions of the Amur Region, the use of varieties with a prolonged growing season was problematic, since from the end of July till August there was intense precipitation, contributing to the development of fungal diseases, and preference was given to precocious varieties maturing before the rainy season. However, in recent years, there has been a significant change in the mode of precipitation, accompanied by increased humidity throughout the period of grain ripening. The study of the relationship between the duration of the growing season and the crop yield of varieties and the size of their grain revealed a number of interesting facts. Under the conditions of the Amur Region, the vegetation period of spring wheat lasts from 77 till 96 days depending on different varieties and different years of research. The longest period was in 2016, the most favorable of all three years of observations, when the yield and weight of 1000 grains were the highest. Varieties with a short growing season had an average yield of 300 g/m2, and varieties with the longest growing season - 412 g / m2. As for the weight of 1000 grains, the same trend was registered - the varieties of laterripening produced larger grain. Under unfavorable conditions of the years 2017 and 2018, the differences between precocious and laterripening varieties were smoothed out. In extreme waterlogged soil during the harvesting period in year 2017, certain advantages in yield was obtained by early maturing varieties, which record plots harvested an average of 197 g/m2, while laterripening varieties - 152 g/m2. However, as to the grain size, the advantage remained in varieties with a longer growing season. In the year 2018, also quite unfavorable for cereals, the advantages of varieties with a longer growing season remained. Thus, the crop yield of relatively precocious varieties averaged 74 g / m2, and laterripening 117 g / m2. The weight of 1000 grains in varieties with a shorter growing season amounted to 27.0 g on average, in laterripening - 28.6 g. The studies have shown that due to the changedclimatic conditions of the Amur Region, varieties with a long growing period have certain advantages over precocious ones and when selecting pairs for crossing and when selecting samples in nurseries, the longer growing period is not a limiting factor.