MASS. EXPERIMENT STATION BULLETIN 400 



Table 1. Rust Reaction of the Mains' Strains of 

 Snapdragons at \^"altham, Massachusetts. 



Strain Number 



Flower Color 

 of Progeny 



Total Number 

 of Plants 



Number of 



Resistant 



Plants 



2-1-1-1-Gl-Fl-Gl Magenta 



7-13-8-1-Gl-Fl-Fl Magenta 



/-13-8-1-Gl-Fl-Gl Magenta 



7-13-8-1-G6-F2-F1-G1 Magenta 



GWl-Gl-Fl-GBl White 



293 (293 X 7-13-8-1-G6-F2-F2) Magenta 



292 (292 X GW1-G4-F2) Magenta 



294 Magenta 



294 Magenta 



294 Magenta 



27 X Fl (A. ghitinosum x GWD 1) . . . .Magenta 



Rust Reaction of Progeny from Crosses Between Mains' No. 294 

 Resistant Strain and Susceptible Commercial Varieties 



Selected plants of the No. 294 resistant strain crossed with the susceptible 

 variety White Rock produced an Fi population of which approximately half were 

 resistant and half were susceptible to rust. Counts made as to segregation of 

 progeny from nine crosses between the No. 294 strain and White Rock yielded 

 364 rust-resistant plants to 365 susceptible plants. In Table 2, the pqn statistical 

 method for determination of goodness of fit has been applied to the data and 

 shows that essential conditions for a good Mendelian segregation ratio of 1:1 are 

 present. 



Table 2. Progeny Segregation for Resistance to Rust in Crosses 

 Between Resistant Strain No. 294 and Susceptible Varieties. 



Fl GENERATION 



