240 GROWTH OF PLANTS 



mammals. It has been showTi that tubers treated with this chemical can 

 be stored for a year or more in bins at 10° C (50° F) or a somewhat higher 

 temperature without sprouting or shrivelling. To prevent sprouting and 

 shrivelling by cold storage for a year the temperature could be very little 

 above 6° C (43° F). Such low storage temperatures are not only expensive 

 and often unavailable but they lead to transformation of much of the starch 

 of the tuber to soluble sugars. As we shall see later, tubers that contain 

 considerable reducing sugars give dark bro^^^l potato chips. The world's 

 annual potato crop is approximately seven and one-half billion bushels a 

 year. Any improvement in storage that will give a net average saving of 

 one cent a bushel is worth seventy-five million dollars a year. 



Dormancy of Gladiolus Corms and Cormels 



Forcing Dormant Corms by Chemical Treatment and Temperature Storage 



Corms of some varieties (Souvenir, Maiden's Blush, and Alice Tiplady) 

 of gladiolus 9- 1^, n could be successfully forced one week after harvest 

 ^vith ethylene chlorhydrin vapors. The dosages were 3 to 4 cc of 40 per 

 cent solution per hter of the enclosure containing the corms and the exposure 

 was two to four days. Ethylene and ethyl ether were not effective. Corms 

 of the Halley variety did not respond to the treatment until one month 

 after harvest; and the corms of Remembrance did not respond to chemical 

 treatment at any time after harvest, but after-ripened ^vith sufficient 

 period of storage mthout treatment. To msure good flowering of fall- 

 forced corms natural light may have to be supplemented with artificial 

 light. In many varieties the chemical treatment was successful only after a 

 cold storage period of three to six weeks at 5° C (41° F). High-temperature 

 storage (30° to 35° C, 86° to 95° F) was not effective if applied immediately 

 after harvest, but had good forcing action for some varieties after the 

 corms had been kept at room temperature for 52 days before they were 

 transferred to high temperatures. Because of the great variation in be- 

 havior of corms of different varieties, both as to depth of dormancy and 

 factors that overcome dormancy, it is evident that each variety must be 

 studied separately to determine the best forcing methods. In some varieties 

 chemical treatment is effective soon after harvest; in others it is effective 

 only after a period at proper storage temperatures, and in still others proper 

 storage alone is the best method of forcing. The attempts at chemical 

 forcing of corms to date should not be considered final. It is possible that 

 other chemicals can be used in combination with ethylene chlorhydrin or 

 still other chemicals found that will give perfect forcing soon after harvest. 



Ethylene chlorhydrin treatment ^~- *'^ increased peroxidase, catalase, 

 pH, sulphydryl, soluble organic nitrogen, and sucrose and decreased the 

 reducing sugar of the corms. Most of these changes occurred regardless of 

 the dormancy of the corms, and there is no evidence that any of them hold 

 a causal relation to the breaking of dormancy. 



