238 BREEDING CROP PLANTS 



\ Le = long internodes 

 Length of internodes. . . f . 



( Lei = very long internodes 



Number of internodes. 



= 20-40 internodes 

 i = 40-60 internodes 

 z = 20-30 internodes 



Absences 



le = short internodes 

 t = 10-20 internodes 



Le is the height factor isolated by Mendel, while T is Keeble and 

 Pellew's factor for thickness of stems which White has interpreted 

 as a factor for internode number and internode length. On the 

 factorial basis given, the phenotypic condition of the tails of 

 which there are three classes would be: 



1. LeT = 20-40 long internodes. 



2. Le Ti = 40-60 long internodes. 



3. LeiTz = 20-30 very long internodes. 



The phenotypic nature of the half dwarfs would be : 



4. Le t = 10-20 long internodes. 



5. le T = 20-40 short internodes. 



True dwarfs would represent the absence of both dominant 

 factors Le and T or let. With the same material that Mendel 

 used, the same results for height have been obtained. 



The inheritance of time of flowering involves several factors as 

 is shown by complicated F* ratios (Tschermak, 1916) (Keeble 

 and Pellew, 1910). Keeble and Pellew found linkage between 

 the factors for thick stems and late maturity and likewise between 

 the opposite condition, thin stems and early maturity. 



Vilmorin (1910) made a large series of crosses with edible 

 pod races. . In some cases both FI and F z produced only plants 

 with edible pods. In other crosses hard inedible pods were pro- 

 duced in FI and ratios of 9 hard to 7 edible were obtained in F 2 . 

 Results may be explained by the supposition that hard pod 

 varieties (development of parchment-like tissue) may be due to the 

 presence of two factors (White, 1917) PPVV. Non-parchment 

 varieties may have either the f ormuladPPvv, ppVV or ppvv. White 

 cites earlier workers who have always found parchmented pods 

 to be inflated and non-parchmented to be constricted. Nohara 

 (1918), in a cross between a Japanese pea and a French variety, 

 both of which produced soft edible pods, obtained a ratio of 9 

 parchmented to 7 non-parchmented in ^2, Results were also 

 explained by a two-factor hypothesis. 



