MODE OF REPRODUCTION IN RELATION TO BREEDING 43 



TABLE V. YIELDS OF FRUIT IN THE FI AND F 2 GENERATIONS OF A CROSS 

 BETWEEN DWARF ARISTOCRAT AND LIVINGSTON STONE WITH THE 



PARENTS 



experiment was carried on for four years (Hayes and Jones, 1916). 

 The lowest increase in yield over the better parent was 11 per 

 cent, and the highest 17 per cent. The cross averaged 15 per 

 cent, more fruit by weight than the better parent. 



In average weight of fruit the cross exceeded the parental 

 average by 8 per cent. It approached the fruit number of the 

 Dwarf Champion parent and exceeded the average fruit number 

 of the parents by 8 per cent. The cross also matured somewhat 

 earlier than the early parent. A cross between the standard 

 varieties, Lorillard and Best of All, was also studied. The 

 parents produced about the same average size and weight of 

 fruit and the cross about the same as the parents. 



A determination of the comparative vigor of F\ wheat crosses 

 and their parents was made by Fred Griffee, a graduate student in 

 plant breeding at the University of Minnesota. For this purpose 

 pure lines of T. durum, T. dicoccum and T. compactum were 

 crossed with pure line varieties of T. vulgare. Intervarietal 

 crosses between pure lines of T. vulgare were also studied, as well 

 as crosses between T. compactum with T. durum and T. dicoccum. 



A determination of the immediate effect of foreign pollen on 

 size of seed was made. Parental plants were emasculated and 

 then some of the spikes were artificially pollinated with pollen 

 from other plants of the same pure line (incrossed seed) and 

 in another series spikes were pollinated with pollen from another 

 variety or species (crossed seed). Only those crosses were com- 

 pared in which the average date of pollination was about the 



