Pod Inoculation Technique with Phytophthora Sojae to Evaluate Soybean Populations for RPS Alleles in Field Plantings
- J. M. Hegstad ,
- D. E. Kyle and
- C. D. Nickell
The pathogen Phytophthora sojae (M.J. Kaufmann and J.W. Gerdemann) can be injected into soybean pods [Glycine max (L.) Merr.] determine presence of phytophthora root and stem rot resistance. The objective of this study was to use pod inoculation in the field to screen soybean F2 populations segregating for Rps alleles. The potential exists to inject different races of the pathogen into pods at different nodes of a single plant, allowing for multiple screenings at a time. Controlling the amount of Phytophthora sojae pathogen injected into each pod was necessary for accurate scoring of disease progression. Injecting 25 μL of Race 1 or Race 3 mycelium inoculum gave optimal symptom differences. The amount of disease progression up the pod to the point of attachment or the complete lack of rotting was determined to distinguish between susceptible and resistant plants, respectively. The data obtained from scoring pods conformed well to ratios of expected models. This technique provides a rapid and inexpensive field screening for identifying resistant or susceptible progeny early in the selection process.
Copyright © . .