64 



Table 20c. Showing Effect of Slow and Rapid Temperature 

 Fall on Freezing to Death of Plant Tissue. 



Material 



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 



Date 



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, 



Time 



22/13 



22/13 



22/13 



22/13 



22/13 



22/13 



22/13 

 22/13 



7M hrs. 

 7M hrs. 

 7Ji hrs. 

 7J£ hrs. 



1\i hrs. 



1% hrs. 



1% hrs. 



1% hrs. 

 1% hrs. 



\% hrs. 



1 hr. 



IVi hrs. 



1 hr.... 

 7}^ hrs 

 1 hr.... 

 7^ hrs. 

 1 hr. 

 iy 2 hrs. 



1 hr. 



7^ hrs, 



Tem- 

 pera- 

 ture 



Results 



-18 Sap wood and pith 



-18 onlyinjuredregions. 



-18 Rice's Seedling 



-18 showed the least in- 

 jury. Othersinjured 



-18 equally. Killing 

 about the same for 



-13.5 twigs whose tem- 

 perature fell rapidly 



-13.5 to -13.5° and those 

 whose temperature 



-13.5 fell slowly to -18°. 



-13.5 (Buds injured worst 

 in rapidly frozen 



-13.5 ones). 



Pith and sap wood 



-11.5 injured. 



Pith and sap wood 

 injured. Very slight 

 browning in cortex; 



-16 . 5 none in cambium. 

 No difference in in- 

 jury between rapid 



-11.5 and slow. Pith and 

 sap wood slightly 



-16.5 injured in both. 



Pith injured in both 



-11.5 cases. 



No other tissues in- 



-16.5 jured. 



Pith injured in both 



-11.5 cases. 



-16.5 



Pith and sap wood 

 -11.5 injured equally in 

 -16.5 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 



