202 Missouri Agr. Exp. Sta. Research Bulletin No. 8 



Table 20c. Showing Effect of Slow and Rapid Temperature 

 Fall on Freezing to Death of Plant Tissue. 



Material 



Date 



Time 



Tem- 

 pera- 

 ture 



Results 



Elberta peach twigs 



Rice's Seedling peach twigs. . 



Jonathan apple twigs 



Chabot plum twigs 



Montmorency cherry 



twigs 



Elberta peach 



twigs 



Rice's Seedling peach 



twigs 



Jonathan apple 



twigs 



Chabot plum twigs 



Montmorency cherry 



twigs 



Elberta peach 



twigs 



Elberta 



peach 



twigs 



Rice's 



Seedling 



peach twigs 



Rice's Seedling 



peach twigs 



Jonathan 



apple twigs 



Jonathan 



apple twigs 



Montmorency cherry 



twigs 



Montmorency cherry 



twigs 



Chabot plum 



twigs 



Chabot plum twigs 



Mar. 

 Mar. 

 Mar. 

 Mar, 



Mar. 



Mar. 



Mar. 



Mar. 

 Mar. 



Mar. 



Mar. 



21,'13 

 21, '13 

 21, '13 

 21,'13 



21, '13 



21,'13 



21, '13 



21, '13 

 21, '13 



21, '13 



22,'13 



Mar. 22,'13 



Mar. 



Mar. 



Mar. 



Mar. 



Mar. 



Mar, 



Mar. 

 Mar. 



22,'13 



22,'13 



22,'13 



22, '13 



22, '13 



22, '13 



22, '13 

 22, '13 



Hi hrs. 

 734 hrs. 

 7M hrs. 

 7M hrs. 



714 hrs. 



1% hrs. 



1% hrs. 



1% hrs. 

 l^A hrs. 



1% hrs. 



1 hr. 



7H hrs. 



1 hr. . . . 

 7H hrs. 

 1 hr. . . . 



7M hrs. 

 1 hr. 

 IVi hrs. 



1 hr, 



7H hrs, 



-18 

 -18 

 -18 

 -18 



-18 



-13.5 



-13.5 



-13.5 

 -13.5 



-13.5 



-11.5 



-16.5 



-11.5 



-16.5 



-11.5 



-16.5 



-11.5 



-16.5 



-11.5 

 -16.5 



Sap wood and pith 

 onlyinjuredregions. 

 Rice's Seedling 

 showed the least in- 

 jury. Othersinjured 

 equally. Killing 



about the same for 

 twigs whose tem- 

 perature fell rapidly 

 to -13.5 and those 

 whose temperature 

 fell slowly to -I80. 

 (Buds injured worst 

 in rapidly frozen 

 ones). 



Pith and sap wood 

 injured. 



Pith and sap wood 

 injured. Very slight 

 browning in cortex; 

 none in cambium. 



No difference in in- 

 jury between rapid 

 and slow. Pith and 

 sap wood slightly 

 injured in both. 



Pith injured in both 

 cases. 



No other tissues in- 

 jured. 



Pith injured in both 

 cases. 



Pith and sap wood 

 injured equally in 

 both cases. 



With these twigs it will be seen that the killing temperature 

 of rapidly frozen twigs was four and a half degrees higher than that 

 of the more slowly frozen twigs, and even then the buds of the rapidly 

 frozen twigs killed the worst. 



In rapid freezing it required from one to one and three-fourths 

 hours to reach a temperature of -20 C. In slow freezing it required 

 from seven to ten hours to reach the same temperature. Many 

 young fruits and succulent plants were also frozen slowly and rapidly 



