Effect of humic preparation on winter wheat productivity and rhizosphere microbial community under herbicide-induced stress

Abstract

The aim of the present work was to study the effect of humic preparation on the yielding capacity of winter wheat, the dynamics of mineral nutrients in the rhizosphere, and the activity of rhizosphere microbial community, as well as the protective properties of humate treatment under the stress caused by the application of a sulfonylurea herbicide. The humic preparation BIO-Don is prepared from vermicompost by alkaline extraction. The effect of humic preparation was estimated in a field experiment. The contents of the mobile ammonium and nitrate, exchangeable potassium, phosphorus, and humus were determined. Sampling and nutrient determination were performed in the tillering, booting, and grain maturing stages. Production experiments on the study of the combined effect of the humic preparation and the sunfonylurea pesticide Granstar Pro were performed in 2015 and 2017. The dynamics of mobile phosphorus in soil was studied. The abundance of culturable bacteria in the rhizosphere and bacterial species with different ecological strategies was determined. The dominant bacterial species were identified by MALDI-TOF mass spectrometry. The results of a small-plot experiment showed that at the tillering stage, the use of humic preparation has led to significantly higher supply of soil with mobile phosphorus. The winter wheat yield was 32.0 dt/ha in the control and 39.2 dt/ha with humic preparation or 22.5% gain in yield. The results of production experiment show that the application of sulfonylurea herbicide induced a chemical stress on winter wheat plants, but the use of humic preparation reduced this effect and increased the availability of phosphorus compounds. The treatment of plants with pesticides caused the general decrease in abundance of bacteria in the rhizosphere. The effect on quickly growing bacteria is more pronounced, while slowly growing bacteria and fungi are more resistant to this impact. The application of humic preparation to winter wheat plantations allows to decrease the toxic effect of sulfonylurea herbicide, improve the supply of soil with mineral nutrients, and increase the crop yield. The favorable effects of humic preparation can be related to the active regulation of phosphorus mobilization by plants through the mechanism of root exudates due to the activation of root microbiota.