POTATO BREEDIITG AND SELECTION. 



17 



number of tuber-bearing plants, less than 13 per seed ball. On the 

 other hand, Keeper, which gave only 13.9 per cent of successes, 

 produced an average of 41.5 tuber-bearing plants per seed ball. 

 As both of these pollen parents are known to produce an abundance 

 of viable pollen, it would seem as if a greater affinity existed between 

 Keeper and Up-to-Date than between Irish Seedlmg and Up-to-Date. 

 In the case of Factor, a total of 74 hand-pollinated flowers, with 

 pollen from 9 varieties, 1 of which was Keeper, produced but 1 seed 

 ball, and that was devoid of seed. 



It is apparent from these data that the Up-to-Date class of plants 

 are, as a rule, poor seed bearers. Frequent examination of the 

 flowers of both Factor and Up-to-Date failed to disclose at any 

 time the presence of viable pollen. To all mtents and purposes, 

 varieties of this class may be considered as belonging to the male 

 sterility group, and in consequence thereof they can not be suc- 

 cessfully employed as pollen parents. 



POTATO CROSSES MADE IN 1910. 



In 1910 a few crosses were made by W. V. Shear and the writer 

 between several varieties of potatoes growing on the Potomac Flats, 

 Washington, D, C. The success of some of these crosses was so 

 striking that it seems desirable to mention them in the present dis- 

 cussion. The specific crosses to which attention is called are those 

 numbered 8708, 8709, and 8718, the data concerning them being 

 presented in Table III. 



Table III. — Results of potato crosses Nos. 8708, 8709, and 8718, made on the Potomac 

 Flats, Washington, D. C, in 1910. 



Field notes. 



Laboratory notes. 





Parentage of cro.ss. 



Date 



crriiiscu- 



lated. 



Date pol- 

 linated. 



Num- 

 ber of 

 flowers 

 crassed. 



Num- 

 ber of 

 seed 

 balls 

 devel- 

 oped. 



Seed ball. 



Num- 

 T)cr of 

 plants 

 potted. 



Per- 



Num- 

 ber of 

 cross. 



No. 



Num- 

 l)cr of 

 seeds. 



centage 

 of seeds 

 germi- 

 nated. 



8708 



Irish Cobbler X Irish 

 Seedlinc 



July 2H 



July :«) 



ri 



fi 



f <* 

 6 

 c 

 d 

 e 



I / 



133 



108 

 KiO 



57 



250 



105 

 ,Sf) 



130 

 47 



221 



170 



78.9 

 79.6 

 85.0 





Total 



82.5 

 80.3 

 70.4 







964 



771 



80 





Irbh flobbler X Irf«h 

 Sce'lling 



July 28 



July 30 



7 



h 







8709 



a 

 b 

 c 

 d 

 e 



2S9 

 200 

 192 

 l(i9 

 134 



2(;i 



ir)5 



1(10 

 121 

 110 



91.3 



77.5 

 80 5 





Total 



71.6 



8fi.O 







9H4 



822 



83.5 







July 28 



July 30 



7 



■> 







«71» Kureka X Keeper 



a 

 h 



c 

 (I 

 e 



250 

 297 

 107 

 1H9 



2ir, 



189 

 238 

 122 

 159 

 190 



73.8 

 80.1 

 73. 1 

 84.1 

 80 





Total 





1,154 



904 



78.3 



















79267"— Bull. 195—15 3 



