148 



Journal of Agricultural Research 



Vol. XV, No. 3 



MATURITY OF THE GRAINS 



The catalase activity of the grains of grasses is determined to a large 

 degree by their maturity at the time of harvest. The immature grains 

 have much higher activity than the mature ones. This holds for Sudan 

 grass, as shown in Table VIII. This table also shows that the higher 

 activity of immature grains is not lost with thorough drying, but that 

 it is maintained after years of dry storage. 



Since the immature caryopses are much smaller than the mature ones, 

 the question naturally occurs, Is the activity per caryopsis about the 

 same in mature and immature seeds? Table XI gives data that answers 

 this question. In this experiment 10 seeds were used in each determi- 

 nation. 



Table XI. — Catalase activity of an equal number of mature and immature seeds of Sudan 

 grass collected at Khartum, Africa {igii9) 



It is evident that the activity per caryopsis, whether mature or imma- 

 ture, is about equal. It is not known whether the embryo (the region 

 of main activity) makes up a greater percentage of the caryopsis in the 

 immature ones or whether there is about constant catalase activity per 

 embryo regardless of size and maturity. The endosperms may also be 

 more active in the immature caryopses. 



Table XII shows the catalase activity of immature and mature cary- 

 opses of Johnson grass about two weeks after it had been harvested. The 

 caryopses were removed from the bracts in a bunch of grains that ranged 

 from medium to thorough maturity, and divided into two lots: Mature 

 (large, plump, dark-brown caryopses), and immature (small, somewhat 

 wrinkled, pink to light-brown caryopses). 



Table XII. — Catalase activity of mature and immature caryopses of Johnson grass; col- 

 lected on September 14, 1917; rim on September 28, 1917 



