BREEDING OF VEGETABLES 



239 



Tschermak (1916) has compiled a brief summary of the mode 

 of inheritance in the garden pea with particular reference to 

 economic characters. Table LX is made up from his summary. 



TABLE LX. INHERITANCE IN THE GARDEN PEA 



1 Segregation apparent in seeds borne by Fi plants. 



All the characters listed above show, as a rule, simple mono- 

 hybrid segregation in F%. In addition to these the following char- 

 acters are intermediate in F\ and give complex ratios in F% 

 according to Tschermak: 



Long pods vs. short pods 

 Broad pods vs. narrow pods 

 Large seed vs. small seed. 



White (1916) has done much to increase our knowledge of the 

 genetic factors and their interrelations. Cotyledon colors were 

 found to be explained satisfactorily by the following formulae: 



GGII = Dominant yellow varieties. 

 ggii = Recessive yellow varieties. 

 GGii = Green varieties. 



(1) 

 (2) 

 (3) 



All peas have yellow pigment in the cotyledon. G is a factor for 

 green pigment and 7 a factor which causes green pigment to fade 

 on the maturity of the seed. "Goldkonig" was the only variety 

 containing the genetic formula ggii. 



Table LXI is a statement of the genetic factors of peas as deter- 

 mined by White (1917), who made a careful review of earlier 

 studies and who has also studied a number of new crosses. 



