TIMING AND THE FLOWERING PROCESS 



143 



100 



o 80 

 q: 



60 



40 



20 



4 hours light 

 nterruption 



Control level 



5 hour light / 

 interruption/ 



/ 



6 12 18 24 30 36 42 48 



TIME OF INTERRUPTION DURING 48 HOUR CYCLES 



Figure 8-4 

 Flowering response of Biloxi soybean to short- and long-light inter- 

 ruptions given during a 40-hr dark period, during 7 cycles of 8-hr light 

 followed by 40 hr of darkness. Length of the interruptions (0.5 or 

 4.0 hr) is indicated by the length of the lines which show the data of the 

 figure. Treatments with 1 .0 or 2.0 hr (not shown) caused only slightly 

 higher flowering at the peaks of the curves than did treatment with 

 0.5 hr of light. Data from Hamner (15). 



vegetative damage itself, which is reversed by the cobaltous ion! 

 Other compounds such as cysteine also reverse 100%. Aspartic acid 

 reverses about 75%, beta alanine about 10%, and glycine not at all. 

 This may imply that cobaltous ion complexes or otherwise reacts 

 with some substance in the leaf cells which is involved in the timing 

 mechanism, and that the product of this reaction is not as stable as 

 that formed with EDTA, but perhaps somewhat more stable than 

 that formed with beta alanine or glycine. It might now be possible 

 to investigate the cell contents with this information at hand in the 

 hopes of finding some biochemical part of the timing mechanism. 



5. Measurement of the Pigment by Determination of Saturating 

 Light Quantities 



By determining the amount of light required to saturate the pig- 

 ment system, we should be able to measure the quantity of pigment 

 in one form or another. The experiment was discussed in Chapter 7, 



