Mar. 



Temperature Efficiency for Ripening of Sweetcorn 797 



Table I shows the changes in chemical composition of the solids in the 

 corn during a typical ripening period. It was found that the rate of 

 ripening was fairly uniform in all the ears selected for the experiment. 

 Therefore the determinations from the four samples taken at each sam- 

 pling period were averaged instead of the first and second samples from 

 the same ears being compared, as was originally intended. Each percent- 

 age in the table, except the first set, represents an average of four deter- 

 minations. The averages for the first date include the determinations from 

 the first samples of ears 1 and 2. The averages for the succeeding dates 

 include the determinations from the first samples of two ears and the 

 second samples of the two ears that furnished the first pair of samples on 

 the previous date. The removal of the first sample from an ear does not 

 affect the rate of ripening in the kernels on the remaining half of the ear 

 if the husks are closed tightly and held in place. 



Table I. — Changes in composition of sweetcorn during ripening 

 [Calculated as percentages of dry weight] 



The chief changes in the percentage composition of the solids in the 

 corn during ripening consist in the depletion of sugars and the increase 

 in starch. In the very early stages the reducing sugars predominate but 

 very rapidly decrease as ripening proceeds. The percentage of cane sugar 

 increases until a maximum is reached and then decreases as the starch 

 increases. The reducing sugars predominate at the stage of highest 

 total sugar content; therefore this stage does not necessarily coincide 

 with the stage of greatest sweetness, as the reducing sugars are not nearly 

 as sweet as cane sugar. The highest content of the latter sugar is the stage 

 of greatest sweetness. The changes in the percentage of fat, crude fiber, 

 and total nitrogen occur during the very early stages of ripening. For the 

 remainder of the ripening period these percentages remain fairly constant. 



The formation and storage of starch is the chief process occurring in 

 the kernels during ripening. This is the resultant of a number of com- 

 plex processes in the plant, but it seems safe to conclude that the rate of 

 starch synthesis in the kernels is the controlling factor for several sup- 

 plementary processes in the ripening of the corn. For example, the rate 



