Intensified Pulse Rotations Buildup Pea Rhizosphere Pathogens in Cereal and Pulse Based Cropping Systems

Abstract

The association of plants and microbial communities is crucial for crop production, and host plants influence the composition of rhizosphere microbiomes. Pulse crops play an important role in the development of sustainable cropping systems, and producers in the Canadian prairies often increase the frequency of pulses in their cropping systems. In this study, we determined the shifts in the fungal community of pea (Pisum sativum L.) rhizosphere, as influenced by the frequency of pulses in rotation, using high throughput sequencing. Six cropping systems containing pea (P), lentil (Lens culinaris Medik., L), hybrid canola (Brassica napus L., C), wheat (Triticum aestivum L., W), and oat (Avena sativa L., O) in different intensities were tested. The fungal communities were assessed at the flowering stage in the fourth and fifth year of the 4-year rotations. Cropping system had a significant impact on the composition of the rhizosphere fungal community, and the effect of crop rotation sequence was greater and explained more of the variation than the effect of previous crops. The rotation with consecutive pulses (WPLP) decreased fungal evenness and increased the proportion of pathotrophs. Fusarium was a dominant and ubiquitous pathotrophic genus. Olpidium virulentus, Botrytis cinerea, Fusarium solani, F. graminearum, and Alternaria eichhorniae were generally more abundant in pulse intensive rotations (WPLP, WLOP, and WPOP), the exception being F. solani which was not promoted by lentil. Reads of O. virulentus and B. cinerea were most abundant in pea preceded by lentil followed by the reads of Mortierella elongata in pea preceded by wheat. Pea consistently had higher grain yield when grown in diversified rotations including wheat, canola/lentil, and oat than rotations with two repeated crops (canola or pea). Cropping system affected the soil physicochemical properties, and soil pH was the main driver of fungal community shift. No evidence of beneficial microorganisms involvement in plant productivity was observed, but the high abundance of pathotrophs in pulse intensified rotations suggests the possibility of pathogen buildup in the soil with increasing pulse frequency. Diversifying rotation sequences minimized disease risk and increased pea production, in this study. Careful selection of plant species appears as a strategy for the management of rhizosphere fungal communities and the maintenance of crop production system’s health.

Soil Bacterial Diversity and Potential Functions Are Regulated by Long-Term Conservation Tillage and Straw Mulching

“…Short-term (3–5 years, etc.) field experiments can help determine the temporary change of soil microbial community in relation to farming practices [ 34 , 37 , 38 ], while long-term (>10 years) field experiments may allow researchers to learn what would happen in the soil environment under different farming practices. Our results from the 18 years of soil treatments (tillage, crop residue management) demonstrated that cropping practices had a significant effect on soil physiochemical properties and the composition of soil microbiomes.…”

Shifts in the Active Rhizobiome Paralleling Low Meloidogyne chitwoodi Densities in Fields Under Prolonged Organic Soil Management

“…However, other Olpidium species are virus-transmitting plant pathogens. Zoospores of Olpidium virulentus colonize roots of various plant species, and were demonstrated to accumulate in crop rotation with multiple pulses including pea (Niu et al, 2018).…”

Cooperation between Broussonetia papyrifera and Its Symbiotic Fungal Community To Improve Local Adaptation of the Host

“…Although studies on H. oryzae are scarce, its role in promoting plant growth has been confirmed (45). Mortierella has been reported to be enriched in the fungal community associated with the pea rhizosphere (46), with its abundance being sensitive to root type (47) and climate change (48). In addition, Mortierella could enhance stress tolerance in host plants (49,50), including adaptability to low temperatures (51).…”