Mar. i8, 19 1 £ 



Respiration of Stored Wheat 



695 



It is commonly recognized in the grain trade that the keeping quali- 

 ties of soft wheats are inferior to those of hard wheat. Because of the 

 relation of respiratory activity to rate of diffusion, it should follow that 

 with the same moisture content respiration would proceed more rapidly 

 in a soft than in a hard or vitreous kernel. A sample of soft red winter 

 wheat of the Fultz variety was obtained from the Experiment Station 

 at Columbia, Mo., and another of white winter wheat from Grand Blanc, 

 Mich. The rate of respiration in these soft wheats at different moisture 

 contents was studied, and it was found that, except at the lower per- 

 centages of moisture, the rate of respiration was higher in the soft red 

 winter wheat than it was in the hard spring wheat, and still higher in 

 the white winter wheat. These data are given in Tables, III, IV, and 

 V, and graphically in figure 2. As shown by the graph, the curves tend 

 to converge at about 1 2 per cent of moisture, indicating that at less than 

 this moisture content the discontinuity of endosperm structure referred 

 to above may exist in sound wheats and respiration proceed at the ex- 

 pense of substances in the germ rather than by oxidation of materials 

 which diffuse to it from the endosperm. 



It may further be seen that the quantity of heat evolved by hard spring 

 wheat containing 14.5 per cent of moisture, as evidenced by the rate of 

 respiration at that moisture content, was evolved by these soft wheat 

 samples when they contained about 13.6 to 13.8 per cent of moisture. 

 This is of interest, in view of the moisture limits prescribed in the United 

 States Grain Standards for wheat, which are I4>^ per cent for No. 2 hard 

 spring, and 1 3 per cent for No. 2 soft red winter, and the same for com- 

 mon white and white club wheat. 



Table III. — Respiration of soft red winter wheat (^ from Missouri, incubated at j/.8'°C. 



for four days 



o Weight per bushel of sample, 61 pouadi. Weight per 1,000 Iceruels, 29.97 gm- Nitrogen on dry basis. 

 1.54 per cent. 



