192 PLANT GROWTH 



food, the tissues are hardened, the fewest roots are killed, 

 and the shoot withstands more drought. 



The gardener who has so cared for the plants during their 

 active period as to enable them to store large quantities of 

 food will always be rewarded by the growth they make when 

 they come out of the dormant period. Growth should be 

 avoided for some time before the dormant period to allow 

 the tissue to harden. Unless buds and branches are hard- 

 ened, they readily winter-kill. 



Even though plants withstand much greater extremes of 

 temperature during the rest period those that are near their 

 northern limit may need to be protected to avoid winter- 

 killing. The best protection is provided during the previous 

 summer by proper growth and food storage after which a 

 moderately moist soil, and low transpiration should be main- 

 tained in the winter. A small mound of earth may give addi- 

 tional protection, but where more is needed, straw may be 

 used if proper precaution against rodents is taken. 



REFERENCES 



Barton, L. V., "Storage of Vegetable Seeds," Contributions from the Boyce Thompson 

 Institute, vol. 7, pp. 323-331, 1935. 



Crocker, W., "Mechanics of Dormancy in Seeds," American Journal of Botany, vol. 3, 

 pp. 99-121, 1916. 



Denny, F. E., and L. P. Miller, "Hastening the Germination of Dormant Gladiolus 

 Cormels with Vapors of Ethylene Chlorohydrin," Contributions from the Boyce 

 Thompson Institute, vol. 6, pp. 31-38, 1934. 



Howard, W. L., "An Experimental Study of the Rest Period of Plants. Seeds," Mis- 

 souri Agricultural Experiment Station Research Bulletin, No. 17, 1915. 



