G 



ARTIFICIAL POLLINATION IN CORN. 



Since the tubes remain in place until all danger from foreign 

 pollen is past, provision must be made for the increasing size of the 

 ear. This can be done by using a coiled instead of a straight Avire 

 to fasten the tube to the ear. The coiled wires are easih' made by 

 Avrapping the -wire around any small cone-shaped object, like tiie 

 point of a lead pencil. The advantage of the cone-shaped coil over 

 a cjdindrical coil is that the tension necessary to straighten the coil 

 is nicely graduated when a cone-shaped coil is used. (Fig. 2.) 



Some experience is necessary to apply the tubes properly, and the 

 exact manner has to be varied slightly for the different types of 

 corn. When the ears are well exserted before silking it has been found 

 best to bring the leaf just below the ear up against the outside of 



the tube and pass 

 the wire around it; 

 otherwise, it is dif- 

 ficult to keep the 

 tube from slipping 

 off the ear as the 

 stalk elongates. 

 The most difficult 

 cases are those 

 where the exsertion 

 of the ear at silking 

 is small, In such 

 cases it is necessary 

 to pass the wire 

 around the stalk as 

 well as around the 

 leaf. "\Mtli varie- 

 ties that have large 

 husk leaves it is Avell to remove them by cutting off the tips of the 

 husks at a point beyond the tip of the young ear; otherwise, the 

 silks become entangled in the mass of leaves and tlie pollen fails to 

 gain access to all. 



While this method can be generally applied only to ears that are 

 to be self-pollinated, it works equally well for artificially crossing 

 two plants that are adjacent in the same or neigliboring rows. In 

 testing Mendelian ratios it will be found convenient to arrange the 

 planting Avith the hybrids betAveen the parents. It Avill thus be pos- 

 sible to apply the method to self-pollinations and crosses betAveen 

 the hybrid and the parents. 



Whei-e the tubes are used it Avould seem that the oidy possible 

 source of contamination Avould be from pollen on the tip of the ear 

 oi- husk leaves at the time the tube Avas applied. To test this possi- 



[Clr. 80] 



Fig. 2. — Cnilod wiro nsod in nttachinjr the paper to the ear. 



