HOW SORGHUM CROSSES ARE MADE 



T. E. Nafziger 



THE sorghum heads which are not 

 to be used for crossing, should 

 either be bagged, or should be 

 entirely removed from the stalks 

 before their anthers open. This prevents 

 pollen from these heads from falling 

 upon the flowers of the experimental 

 plants before the emasculation [removal 

 of stamens] of their flowers or while 

 the process of emasculation is taking 

 place. 



A branch or "ray" is selected from 

 a panicle [flower cluster] of a plant of 

 a pure strain, which has none of the 

 anthers or stigmas exposed. The blos- 

 soms must be emasculated before the 

 anthers emerge. Care must be taken 

 however, not to open the blossoms while 

 in their earlly stages of formation, as 

 injury may result to the interior, caus- 

 ing the pistils and the glumes [corre- 

 sponding to petals in ordinary flowers] 

 to dry up. 



A BLUNT NEEDLE MAKES A GOOD TOOL 



In emasculating the blossoms, an in- 

 strument should be used that is not so 

 sharp as to puncture the anthers, and 

 yet not so blunt as to mutilate the in- 

 terior of the flower. A steel dissecting 

 needle with the point slightly blunted, 

 can be employed with a fair degree of 

 success in removing the stamens. A 

 common pin could be used, were it not 

 for the slight possible chance of injury 

 to the flower due to the material used in 

 the construction of the pin. 



All of the flowers on the branch 

 chosen, except ten or a dozen, are then 

 carefully removed from the branch. 

 These remaining flowers are emas- 

 culated by prying the glumes apart very 

 carefully with the dissecting needle. 

 Placing the needle under the three sta- 

 mens, they are removed one by one from 

 the interior of the flower. If an anther 



has been punctured during the process 

 of removal, or if the hands have been 

 in contact with punctured anthers, the 

 hands and the needle should be washed 

 in alcohol, and allowed to dry thor- 

 oughly before proceeding with the 

 work. 



The branch is bagged, after the flow- 

 ers are emasculated, with a small par- 

 affined paper bag, to prevent pollen 

 from reaching the stigmas of the emas- 

 culated flowers. The panicle which has 

 the attached branchy is also bagged (pre- 

 ferably with a waxed bag) to save the 

 pollen for the reciprocal cross. The 

 panicle is then tagged with a label show- 

 ing the number of the strain, the num- 

 ber of the plant, the number of the re- 

 ciprocal, and the date when emascula- 

 tion was done. A representative tag is 

 reproduced in the figure below. 



N = strain number (fe- 

 male). 



1 = plant. 



Nj = strain number upon 



which the cross is made 

 (male). 



The same procedure as outlined 

 above, is followed in emasculating the 

 flowers of the strain upon which the 

 reciprocal cross is to be made. The tag 

 on the panicle of the reciprocal would 

 show the following. 



The first line in the notation on the 

 tag indicates that the tagged plant is 

 the female X^ and that N is the male 

 plant. 



321 



