242 



GROWTH OF PLANTS 



but one to three months later. Fig. 92 shows the forcing action of ethyl- 

 ene chlorhydrin on dormant cormels. By April cormels of many varieties 

 after-ripen in storage and do not need chemical treatment to induce growth. 

 Storage of cormels of these varieties at 3° to 10° C (37° to 50° F) overcame 

 the dormancy more readily than higher storage temperatures. 



Cormels of seven varieties (Giant Nymph, Mr. W. H. Phipps, Dr. E. F, 

 Bennett, Mrs. F. C. Peters, Minuet, Willbrinck, and Golden Measure) 

 are especially dormant.^*' When these cormels are stored at the best low 

 temperature until May most of the cormels of each variety fail to produce 

 plants during the summer when planted in soil without treatment. Proper 

 ethylene chlorhydrin treatment in the spring increased the number growing 

 by many-fold in three varieties and by 100 to 200 per cent in two varieties. 

 Two varieties could be forced by ethylene chlorhydrin only after this long 

 period of cold storage. 



It is important to get a high percentage of germination of cormels of 

 gladiolus in order to have them develop as quickly as possible into flowering- 

 sized corms. Fig. 93 shows the great increase in size and number of corms 



Figure 93. Yields obtained in 

 the autumn from 150 gladiolus 

 bulblets, variety Minuet, stored 

 over winter at 15° C (59° F) and 

 planted in the spring. Left: bulb- 

 lets soaked 3 days in H2O and 

 planted. Right: bulblets soaked 

 3 days in H2O, then exposed to 

 vapor of ethylene chlorhydrin, 

 using 1 cc of 40 per cent ethylene 

 chlorhydrin per 100 g of bulblets, 

 weight before soaking. 



produced during the summer when a given number of cormels of a dormant 

 variety are treated with ethylene chlorhydrin in the spring. This is the 

 chief way of multiplying flowering stock of the variety. But in general the 

 grower does not care to have them germinate until time for spring plant- 

 ing outside. The situation is different with dormant corms for they are 

 often forced for winter flowers. Cormels of varieties that are only moder- 

 ately dormant should be stored at a low temperature, about 5° C (41° F), 

 until spring and planted without treatment. Cormels of very dormant 

 varieties should be similarly stored and treated with ethylene chlorhydrin 

 before planting in the spring. In case of new very choice varieties it is 

 possible that by combination of temperature and chemical treatment one 

 could get two growing periods during the year, one in the greenhouse and 



