1919] 



YOUNG SEED DISINFECTION 



157 



ficiently long treatment of both agents mentioned, and some, 

 such as barley, that are very sensitive and cannot be so 

 treated. I have not been able to free barley from contamina- 

 tion in more than 75 per cent of the seed used. There are many 

 other seeds that are easily killed by any germicide that will 

 be effective against the adhering microorganisms. In conclu- 

 sion, therefore, it would seem necessary to continue to treat 

 the various seed differently and with different disinfectants. 

 One of the most important considerations is that there are un- 

 doubtedly different contaminating organisms. 



- 



TABLE IV 



SUMMARY GIVING BEST TREATMENTS FOR VARIOUS KINDS OF SEEDS 



(For percentage of germination in each case, see Tables I, II, and III) 



Disinfectant 



Calcium 



hypochlorite 



(CaOCl.) 



Seed 



Formaldehyde 

 (HCHO) 



Mercuric 

 chloride 



(HgCI.) 



Cucumber 



Lettuce 

 Sugar beet 



Bean 

 Cotton 



Corn 

 Cucumber 



Alfalfa 

 Sunflower 



Wheat 

 Potato 



Corn 



Field peas 



Radish 



Alfalfa 



Barley 



Garden 



peas 

 Dwarf bean 

 Garden 



cress 

 Nasturtium 

 Onion 



Lupines 



Strength 



of 



disinfectant 



Full 

 Full 

 Full 



2-3% 

 3-4% 



2-3% 

 2-3% 



3% 

 2-3% 

 2-3% 



3-4% 



1% 

 1% 

 1% 

 1% 

 1% 



1% 

 5% 



5% 

 5% 

 5% 



5% 



Time of 

 exposure 



11 hrs. 

 2-6 hrs. 

 11 hrs. 



30 min. 

 45 min. 



Previous treatment 



None 

 None 

 70% alcohol, 1 min 



15 

 30 

 30 

 30 

 30 



min. 

 min. 

 min. 

 min. 

 min. 



45 min. 



20 min. 

 20 min. 

 40 min. 

 40 min. 

 10 min. 



20 min. 

 20 min. 



20 min. 

 20 min. 

 20 min. 



40 min. 



None 



Soaked in H 2 0, 12 hrs., lint 



removed with H2SO4 

 None 

 None 

 None 



Soaked in H2O, 18 hrs. 

 Soaked in H 2 0, 6 hrs., 1% 



H2O2, 10 min. 

 70% alcohol, 1 min. 



None 

 None 

 None 

 None 

 70% alcohol momentarily 



None 

 None 



None 



Soaked in H 2 0, 12 hrs. 



Soaked in H 2 0, 12 hrs., then 



in 1% H2O2, 10 min. 

 1%H 2 2 , 10 min.; 70% 



alcohol, 1 min. 



This work was done at the Missouri Botanical Garden 

 Graduate Laboratory under the direction of Dr. B. M. Duggar. 



