SELF, CLOSE, AND CROSS FERTILIZATION OF 



BEETS 



Harry B. Shaw 



Federal Horticultural Board, U. S. Department of Agriculture 

 (with plate 20) 



The writer distinguishes three types of fertiHzation, namely, 

 (i) self fertilization, meaning that effected by pollen of the self- 

 same flower; (2) close fertilization, referring to that effected by 

 the pollen of one flower upon any other flower of the same plant; 

 (3) cross fertilization, that effected between the flowers of any 

 two plants: 



The protandrous character of the beet flower was demonstrated 

 by Darwin and Rimpau. Although apparently the present 

 methods of beet breeding have largely been based on the evidence 

 of Darwin and Briem as to the susceptibility of the beet to close 

 fertilization, the published data of these writers are not conclusive 

 on this point. For the purpose of creating and continuing pure 

 lines of sugar beets it has been the practice to isolate individual 

 beets by inclosing each selected plant in a small tent of white 

 fabric during the blooming period. (Plate i.) In more recent 

 practice several plants are inclosed in each tent, cross pollination 

 taking place among the inclosed plants. 



Samples of the fabric used by several well-known German beet- 

 seed growers were obtained. The most closely woven of these 

 is very similar to that used in the writer's experiments. (Fig. i , c.) 

 Under such tents, single beets showed a fertilization of about 23 

 per cent, on the average. A somewhat greater percentage of 

 fertilization has been obtained by European writers under their 

 isolation tents. 



Although the mechanism and sequence of beet bloom appear 

 to be especially favorable for close fertilization, it became doubt- 

 ful to the writer whether beets really are susceptible to close 

 fertilization; it also became almost a matter of certainty that the 



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