Changes in the Rhizosphere Biome Depending on the Variety of Wheat, Timing of Its Growing Season, and Agrochemical Components in the Soils of Italy

Abstract

The purpose of this research is to investigate the interactions among wheat varieties and microorganisms within rhizosphere and how conventional agriculture affects these dynamics during the growing season. Indeed, little is known about how commercial bread varieties modulate root exudates and how agrochemicals affect the microbiological processes. Therefore, this study investigated the changes in soil microbiological features such as enzyme activities (β-glucosidase, xylosidase, glucoronidase, chitinase, leucine-aminopeptidase, acid and alkaline phosphomonoesterases, inositol phosphatase, phosphodiesterase, pyrophosphatase–phosphodiesterase, arylsulphatase) and microbial biomass as a function of treatment (fungicides and plant growth regulator—PGR) and wheat varieties (Skyfall, SY Moisson, Aquilante, Bandera, Tintoretto, Antille, and Bologna) at the sowing, heading, and harvesting stage. A total of 168 samples (2 treatments × 7 varieties × 3 field replicates × 4 sub-samples taken in each plot) were collected in each period and analyzed. We found that soil microbial biomass was a sensible indicator in the fungicide/PGR application, with reduced values in treated plots at the heading. At this stage, the soil enzymatic activities were in general more expressed, confirming that the microbial processes are more proactive due to the growth of plants. Overall, the soil enzymatic activities responded differently according to the wheat varieties, highlighting specific capabilities to interact with microbes.