Disease reaction to Rhizoctonia solani and yield losses in soybean

Seedling blight and root rot caused by Rhizoctonia solani are important constraints to the expansion of soybean (Glycine max) production in Alberta, Canada. The reaction of 21 soybean genotypes to R. solani was assessed in inoculated field trials in Alberta in 2014â 2016. Inoculation with R. solani resulted in a significant reduction in stand, nodulation and yield and a significant increase in root rot severity for all of the soybean genotypes. The genotype P001T34R had lower reductions in stand establishment compared with NSC Portage RR, TH29002RR, TH27005RR, or LS003R22, and there were inconsistent variations in yield loss among the genotypes in two of the three site-years. No significant variation in disease severity or nodulation was observed among the genotypes. Stability analysis showed the soybean genotypes P001T34R, 23-60RY, NSC VitoRR, and NSC TilstonRR2Y had higher and more stable stand establishment, while 900Y01, 23-60RY, P001T34R and P002T04R had higher and more stable seed yield in comparison with the other genotypes in this study. The study also revealed that R. solani caused a loss of 48% in stand establishment and 52% in seed yield. Root rot severity ranged from 0.38â 2.36 on a scale of 0-4 among the genotypes, but it was not consistent over the trials. Root rot severity and yield loss increased with increasing inoculum density, while stand establishment, nodulation and seed yield declined. Regression analysis showed that stand establishment, nodulation, and yield were strongly positively correlated, but strongly negatively correlated with root rot severity.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author