The impact of phosphorus management on the canola soil and root-associated microbiomes
Date
2022-03-08
Authors
Liu, Mengying
Mooleki, Patrick
Schneider, Dave
Kochian, Leon V.
Helgason, Bobbi L.
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Abstract
Canola (Brassica napus) has high phosphorus (P) demand, but its small seeds are susceptible to P fertilizer toxicity. As a result, optimizing P fertilizer management and fertility for canola can be aided by a better understanding of microbial contributions to plant P uptake. To decipher the impact of different P application strategies on canola growth and its soil and root-associated microbiome, we conducted a 2-year field experiment at Scott, SK using commercial Invigor L233P. Three rates of P (0, 35 and 65 lb P2O5 ac-1 as monoammonium phosphate; 0P, 35P and 65P) were combined with two fertilizer placements (1- and 4-inch openers; 1” and 4”) in a replicated (n=4) randomized complete block design. Bulk soil, rhizosphere soil, roots and shoots were sampled at the 5-6 leaf and peak flowering stages. Canola P uptake was higher in the 35P 1” treatment when plants at the 5-6 leaf stage but by flowering, was the greatest in the 65P 1” treatment. Plant density was consistently higher in 4” vs. 1” opener treatments at both 35P and 65P. Despite these differences, there were no differences in yield for any of the P treatments, indicating that P was not the most determining factor for canola yield in our experiment. Using amplicon-based DNA profiling, we found that differences in the bulk soil, rhizosphere soil and root communities explained 36.4% of bacterial and 17.7% of fungal community variance, and that sampling year and plant growth stage also had strong effects on the microbial communities. Soil P rate and opener width affected only the root community structure, where specific taxa (e.g., Gammaproteobacteria and Sodariomycetes) were most responsive to P application. The response of individual bacteria and fungi in the roots under different P management strategies is currently under investigation to better understand microbial contributions to plant P uptake.
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Canola, Phosphorous, Fertilizer, Microbiome
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Soils and Crops Workshop