CHAPTER V 

 CONTROLLING POLLINATION 



Methods of controlling pollination have received consider- 

 able attention. Protecting self-fertilized plants from occasional 

 natural crosses would seem to be a necessity in careful studies 

 of heredity. The lack of technic of crossing may be a cause of 

 failure to improve a particular crop. This entire field is one in 

 which actual practice is needed before the worker can hope to 

 accomplish best results. A few general principles will be given. 



Selfing Plants Artificially. Certain methods have already 

 been worked out for particular crops. As an example, in the 

 tobacco crop artificially self-fertilized seed may easily and cheaply 

 be produced. The practical grower can well afford to save 

 his seed by this practice. Before any of the blossoms have 

 opened, the terminal inflorescence should be covered with a 

 manila paper bag. The 12-lb. size has been found satisfactory 

 for this purpose. If a few flowers have already been pollinated 

 these may be removed before bagging. After a week or 10 days 

 has elapsed, the bag should be taken off and all flowers except 

 from 50 to 60 removed and the dead corollas shaken off. After 

 sufficient flowers have been fertilized the bag may be removed, as 

 the seed will mature somewhat more rapidly than when enclosed. 



Self-pollination of the tomato may be accomplished in very 

 much the same manner as with tobacco. Small-sized bags are 

 needed. In this case it is necessary to jar the flowering branches 

 upon which the bags are placed as the tomato does not set seed 

 freely unless some such practice is followed. 



f Artificial self-pollination in corn is very easy. The ear and 

 tassel may each be covered with a 12-lb. manila paper bag. 

 It is necessary to cover the ear before any of the silks show. 

 Foreign pollen accidentally enclosed with the tassel will not 

 function after a period of more than two days. Approximately 

 two to five days after the ear has been bagged the silks will have 

 grown out and will be ready for pollination. The most favorable 

 time for pollination is when the silks are 2 to 3 in. long, although 

 the silks are receptive when much longer. 



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