164 



Journal of Agricultural Research 



Vol. XV, No. 3 



large, heavy, thoroughly mature seeds from the lighter, more poorly 

 matured seeds was made by means of vertical air-blast seed separator. 

 The results of the experiment are given in Table XXVII. 



Table XXVII. — Oxidase activity of mature and immature seeds 



The mature Sudan grass seed was slightly more active than the imma- 

 ture, whether the whole caryopses or only the embryo ends were used. 

 With Johnson grass seed, however, the immature seed was considerably 

 more active than the mature seed. 



OXIDASE ACTIVITY AS RELATED TO AGE OF SEED 



The material consisted of a sample of Johnson grass seed about 3 years 

 old ; two samples of Johnson grass seed from a common original selection, 

 one of which was i year old and the other about i month old ; and two 

 samples of seed of Amaranthus retro flexus, one over 2 years old and the 

 other about 2 weeks after harvesting. The results of the experiments 

 are given in Table XXVIII. 



Table XXVIII. — Oxidase activity as related to the age of the seed 



Material. 



Johnson grass 141 7 



Johnson grass 8599 



Do 



Do 



Amaranthus retroflexus. 



Do 



Do 



Do 



3 years. . 



1 year. . . 



..do 



3 weeks . 



2 years. . 

 2 weeks . 

 2 years. . 

 2 weeks . 



Quan- 

 tity of 

 powder 

 used. 



Mgm. 

 500 

 SCO 

 250 

 250 

 50b 

 500 

 250 

 250 



Reduction of pressure. 



10.5 mm. in 4j^2 hours. 

 29.5 mm. in 4>^ hours. 

 68 mm. in 19 hours . . . 

 95 mm. in 19 hours . . . 

 19.5 mm. in 4'^ hours. 

 38.5 mm. in 4>^ hours. 

 25.5 mm. in 10 hours. . 

 45 mm. in 10 hours . . . 



Ratio of 



activity, 



old to new. 



0-35 

 .72 



•51 



•57 



The intensity of oxidase activity decreases markedly with age. One- 

 year-old Johnson grass seed was a little more than two-thirds as active 



