234 



Journal of Agricultural Research 



Vol. XX, No. 3 



Table X. — Relation between strength of formaldehyde solution, condition of seed coat, 

 and the cumulative injury to Early Baart wheat well spread during the drying period a 



Length of 

 drying period. 



iM hours 

 4 hours.. . 

 24 hours.. 



3 days 



6 days 

 14 days. . . 



45 per cent formaldehyde 

 solution. 



Seed coats 

 unbroken. 



Ger- 

 mina- 

 tion. 



Per 

 cent. 



ioo 



65 



Height 



of 

 plants. 



Seed coats 



broken over 



embryo. 



Ger- 

 mina- 

 tion. 



Per 



cent. 

 60 



Height 

 of 



plants 



Cm. 



5 



1.2 per cent formaldehyde 

 solution. 



Seed coats 

 unbroken. 



Ger- Height 

 mina- j of 

 tion. plants 



Per 

 cent. 

 95 

 95 

 95 

 100 

 95 

 95 

 95 



Cm. 

 5-0 



3- 5 

 3-5 



4-0 

 2. o 



2-5 



2. o 



Seed coats 



broken over 



embryo. 



Ger- 

 mina- 

 tion. 



Per 

 cent. 



1. 1 per cent formaldehyde 

 solution. 



Seed coats 

 unbroken . 



Height Ger- 



of I mina- 



plants.l tion. 



Cm 



Per 



cent. 

 95 



100 

 100 

 100 

 100 

 100 

 90 



Height 

 of 



plants. 



Cm. 



5-o 

 4-o 

 5-o 

 5.0 

 5-o 

 5.0 

 3-5 



Seed coats 



broken over 



embryo. 



Ger- 

 mina- 

 tion. 



Per 



cent. 



95 

 95 



100 



Height 



of 

 plants. 



Cm. 



4-5 

 4.0 

 5-o 

 5-o 

 5-o 

 3-0 

 3-5 



a The average heights of the plumules after 6 days are given for each germinating sample, because a 

 comparison of these for all the samples of any one test shows any injury indicated by retardation which 

 sometimes would not be shown by the germination percentage alone. A heighth of less than one centi- 

 meter (1-) indicates extreme injury, with usually stunted, deformed plumules which could not reach 

 the surface of the soil. 



In brief, Table X shows that when treated seed is dried rapidly by being 

 thinly spread in the laboratory, it is uninjured by a o. i per cent solution 

 even if the embryos are exposed by broken seed coats ; that seed treated 

 with a 0.2 per cent solution is uninjured if the seed coat is perfect, but 

 severely injured after 24 hours if it is broken; and that, with a 4.5 per 

 cent solution, perfect seeds are slowly injured and that seeds with broken 

 testas are injured by the dip into the treating solution, which injury 

 rapidly increases upon drying. The cumulative nature of this seed 

 injury is well shown by the germination data for all these injured 

 samples. 



Lest there be any misunderstanding, it may be well to consider again 

 the case of treated seed which is sealed damp. It may be asked at this 

 point that if aeration is necessary to prevent injury from formaldehyde 

 fumes, how can seed stored damp in sealed jars remain uninjured? The 

 answer is probably to be found in the fact that paraformaldehyde does 

 not form on damp seeds; hence the damp seeds are not surrounded by 

 concentrated formaldehyde vapor. The moisture in the jar is a weak 

 dilution, and neither it nor the amount of formaldehyde in the air 

 in the presence of so much water is strong enough to injure the seed. 

 Moreover, the formaldehyde does not remain on damp seeds indefinitely, 

 owing to the activity of microorganisms which decompose it. The case 

 is different with solutions stronger than o. 1 per cent, however. Damp 

 seed is slightly injured by a 0.2 per cent solution after 24 hours' storage, 

 and a 4.5 per cent solution is fatal in a sealed jar. Whether in these 

 instances it is the solution on the seed which injures or the resulting 



