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BULLETIN 289, TJ. S. DEPARTMENT OF AGRICULTURE. 



ARTIFICIAL MANIPULATION OF CLOVER HEADS. 



Experiments were conducted to determine, if possible, the effect 

 on seed production of various types of artificial manipulation of the 

 clover heads while the flowers were in bloom (fig. 3) A sufficient 

 number of heads were selected on each plant so that the work could 

 be conducted on. heads covered with tarlatan (fig. 4) and on heads 

 exposed to the action of insects. The experiments on the heads 

 exposed to the action of insects were to determine whether the 

 artificial manipulation of the flowers would have any harmful effect 

 on seed production. The different treatments given the heads 

 covered with tarlatan were to determine whether fertilization could be 



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Fig. 3.— A screen cage (in the background) in winch bumblebees were confined. Hand-pollination work 

 is in progress in the foreground. 



produced by any method of artificially manipulating clover flowers 

 from which insects were excluded. For this work, plants were 

 selected bearing at least eight heads which would come into bloom 

 at approximately the same time. These plants were taken at random 

 and each marked with a stake, as shown in figure 5. The heads on 

 each plant were labeled from A to H, inclusive, and treated as shown 

 in Table I. 



These experiments were conducted in Iowa, in 1911 on 50 plants 

 at Ames, and 25 at Altoona, and in 1912 on 70 plants at Ames. 



Table II gives the results obtained on 25 representative plants, 

 selected from the entire number, and also the average seed yield per 

 head of the entire 145 plants experimented within 1911 and 1912. 



