306 



LEROY POWERS 



Weight of Fruit and Its Component Characters 



The data on weight per locule, number of locules, and weight per fruit for 

 the Porter X Ponderosa hybrid and parental populations are given in Tables 

 19.4 and 19.6. On the arithmetic scale, smaller numbers of locules show par- 

 tial dominance. On the logarithmic scale the means of the Fj and F2 popula- 

 tions are not significantly different from the average of the means of the 

 Porter and Ponderosa populations. The mean of the Bi to Porter population 

 is not significantly different from the average of the means of the Porter 

 and Fi populations. The mean of the Bi to Ponderosa population is not sig- 



TABLE 19.6 



THE ARITHMETIC AND LOGARITHMIC MEANS FOR NUMBER OF LOCULES 



AND WEIGHT PER FRUIT OF PORTER X PONDEROSA TOMATO 



HYBRID AND PARENTAL POPULATIONS* 



* Grown at Woodward, Oklahoma, in 1941; original data taken in numbers and grams and transformed to 

 logarithms to obtain the means and standard errors of the logarithms. 



nificantly different from the average of the means of the Fi and Ponderosa 

 populations. Hence, on the logarithmic scale there is no dominance, and the 

 data indicate that the genetic variability follows the logarithmic scale. In 

 other words, the effects of the genes differentiating weight per locule are 

 multiplicative. This is true of both the intraallelic and interallelic inter- 

 actions. 



Thus on the logarithmic scale number of locules shows no dominance, 

 weight per locule shows heterosis (Table 19.4) and the two combine addi- 

 tively to give weight per fruit. For weight per fruit the Fi indicates partial 

 dominance of greater weight per fruit, the Bi to Ponderosa complete domi- 

 nance, and the Bi to Porter no dominance. On the arithmetic scale the two 

 component characters unite multiplicatively, and the Fi indicates partial 

 dominance of greater weight per fruit, the Bi to Ponderosa complete domi- 

 nance, and the Bi to Porter partial dominance of smaller weight per fruit. 

 Then it is clear that regardless of scale, one of the component characters 

 shows some degree of dominance, the other heterosis. They combine to pro- 

 duce the main character which in turn shows some degree of dominance. 



