Killing of Plant Tissue by Low Temperature 



237 



Kind of Root 



Two-year 

 Kieffer pear 

 on Japan 

 stock 



Two-year 

 Kieffer pear 

 on Japan 

 stock 



Two-year 

 Kieffer pear 

 on Japan 

 stock 



Kieffer pear 

 roots 



Kieffer pear 

 roots 



Kieffer pear 

 roots 



Kieffer pear 

 roots 



Location 



of 



Root 



Largest 

 Diameter I Length 



Tem- 

 pera- 

 ture 



Results 



4 inches below 

 surface 



4 inches below 

 surface 



4 inches below 

 surface 



Top even with 

 surface 



. 5 in. 



12 in.... 



.45 in. 



10 in. 



-10 



-10 



.3 in. 



6 in. 



4.5 in below 

 surface 



6 inches below 

 surface 



1.2 in. 



15 



in. 



-10 



. 6 in. 



12 



in. 



-10 



-10 



.3 inches be- 

 j low surface. . 



.4 in.. 



12 in.... -10 



,3 in. 



8 in. 



-10 



Cambium and 

 cortex injury 

 throughout. 

 Sap wood in- 

 jury in last 8 

 inches. 



Cambium, cor- 

 tex and sap 

 wood injured. 



throughout. 



Cortex and cam- 

 bium injured 

 severely 

 throughout; 

 sap wood in 

 last 5 inches. 



No injury in 

 first 8 inches; 

 slight injury 

 in cortex and 

 cambium in re- 

 mainder. 



No injury in 

 first 2 inches; 

 cambium and 

 cortex injury 

 in remainder; 

 pith injury in 

 last 5 inches. 



No injury in 

 first 3 inches; 

 cambium and 

 cortex and sap 

 wood injury in 

 remainder. 



Cambium and 

 cortrx injury 

 throughout. 

 Sap wood in- 

 jury in last 4 

 ii 



jury in 

 inches.. 



