Soybean fungal soil-borne diseases: a parameter for measuring the effect of agricultural intensification on soil health

Abstract

The aim of this study was to investigate the influence of agricultural intensification on soil microbial diversity, chemical and physical parameters, and the decrease of the incidence of sudden death syndrome (Fusarium crassistipitatum) and charcoal rot (Macrophomina phaseolina) in soybean. Soils under different management systems were evaluated during 2 crop cycles: soybean monoculture for 24 and 11 years, soybean-maize rotation for 15 and 4 years, 1 year of soybean, and native vegetation. The incidence of both soil-borne diseases was higher under monoculture than under rotation. Increased populations of potential biocontrol agents (Trichoderma spp., Gliocladium spp., fluorescent pseudomonads) were associated with rotation treatments, especially in 2010-2011. The comparison of agricultural vs. native vegetation soil and the average of agricultural cycles showed that microbial biomass carbon and glomalin-related soil protein were higher in the rotation system than in monoculture (50% and 77%, respectively). Furthermore, from the community-level functional diversity (Biolog Eco plates), McIntosh index showed lower functional diversity in monoculture than in rotation and native vegetation plots. Agricultural intensification reduced microbial biomass carbon, glomalin-related soil protein, organic matter, total nitrogen, aggregate stability, and yield, and increased bulk density. Soil quality degradation was associated with the establishment of soil-borne pathogens and increased soybean plant susceptibility to disease.

<b>Agrosilvopastoral system enhances suppressiveness to soybean damping-off caused by <i>Rhizoctonia solani</i> and alters <i>Fusarium </i>and <i>Trichoderma</i> population density

“…As previously suggested (Pérez-Brandán et al, 2014), there is a positive effect of Trichoderma on the greater diversity of plant species, confirmed in the present work in the ASP treatment. Soil moisture is also known to be an important factor influencing Trichoderma spp.…”

“…and Trichoderma spp. in each soil sample were estimated by dilution plating on agar (Pérez-Brandán et al, 2014). An aliquot of 10 g of soil was diluted in 90 mL of sterile distilled water and stirred for 90 minutes at 170 rpm on an orbital flask shaker.…”

Continuous Cropping Alters Multiple Biotic and Abiotic Indicators of Soil Health

“…), which act as biological control agents against soil-borne pathogens (e.g., Fusarium spp.) [108,109]. Similarly, some studies have also reported that long-term CC may also decrease the microbial biomass P [110] and C contents [111].…”

Cropping systems on root rot and soybean seed yield

“…In order to increase yield, continuous investment in modern soil management technologies, liming, fertilization, and seeding, associated with efficient weed, pest and disease control is needed (THOMAS & COSTA, 2010;FREITAS, 2011), in addition to suitable crop rotation. Expansion of soybean growing area has prompted an increase in monoculture farming (PEREZ-BRANDAN et al, 2014); thereby, raising the occurrence and intensity of diseases. All parts of the soybean plant are susceptible to plant pathogens (HARTMAN et al, 1999), especially fungus-related diseases associated with root rot (RR) (HENNING, 2009).…”

“…* Corresponding author. : soybean-oat+soybean-oat, soybean-maize+soybean-maize, soybean-wheat+soybean-wheat and soybean-pasture+soybean-pasture BRANDAN et al, 2014;KLINGELFUSS et al, 2007). Root rot and early plant death (COSTAMILAN, 1999;SARR et al, 2014) affect pod filling, resulting in small, green or deteriorated seeds that compromise seed lot quality and reduce crop yield (SHADAKSHARI et al, 2014).…”