INFLUENCE OF ENVIRONMENTAL FACTORS ON SPRING WHEAT DISEASES PROGRESSION

Abstract

The complex of environmental factors of the Middle Amur region has a significant impact on the development of spring wheat diseases caused by different pathogens. The aim of this research was studying the influence of ecological factors of the Middle Amur region on the development of infection and establishing the correlation between climatic factors during the main periods of plant growth and development and disease severity. The research was conducted in 2011-2015 in cereal-soybean rotation on a meadow-brown heavy loamy soil. Soil characteristics: humus (by Tyurin) - 4.6%; P₂O₅ (by Kirsanov) - 4,3 mg/100 g of soil; K₂O (by Maslova) - 20 mg/100 g of soil; pH of arable layer’s salt extract - 4,8...5,0. The object of research - spring wheat diseases: fusarium head blight, root rot and helminthosporiosis. The level of disease severity was measured according to the methods of state varieties testing, field surveys on root rots were conducted twice: during the booting ang milk ripening stages; on spot blotch and fusarium head blight - during the ear emergence and dough stages. Fusarium head blight development in the interphase (seedling growth - tillering) in the conditions of the Middle Amur region is affected by precipitation (r = 0,624) and high surface air temperatures (r = 0,654). In the subsequent periods of plant growth and development heavy rainfall restrains disease dispersal (r = -0,832), high surface air temperatures create worse conditions for pathogens development as well. Hydrothermal conditions of the Middle Amur region from sowing till flowering play little and unstable role in the development of helminthosporium disease of spring wheat. During the flowering-ripening period a strong negative correlation was found between helminthosporiosis severity and precipitation (r = - 0,851). High air temperatures inhibit helminthosporium development, as evidenced by the determined correlation dependance (r = -0,809). The root rot infection in the Middle Amur region conditions appear at different stages of plant development, and weather conditions of the whole growing season contribute to its formation.