32 MISC. PUBLICATION 4 3 4, U. S. DEPARTMENT OF AGRICULTURE 



USE OF DYES AND STAINS 



A number of investigators, notably the Russians, have been experi- 

 menting with the use of various chemical stains and dyes, which, when 

 applied to the contents of a seed, will indicate by color whether the 

 embryo is alive or dead. This work is still in an experimental stage 

 but it is hoped that it will lead to a simple and accurate method of 

 determining viability. The promptness with which such a test could 

 be made is an obvious advantage. 



RELATION OF GERMINATION TO CUTTING TESTS 



Table 4 shows the relation of laboratory germination to cutting 

 tests. All species which respond to pre treatment of any kind were 

 given the proper treatment before testing. Although the table cannot 

 be used indiscriminately, it does give the nurseryman some idea of 

 these relationships. For instance, Russian-olive and honeylocust 

 both yielded 96 percent or more of well-filled seed by the cutting test, 

 but the former had an average germination of only 32 percent, while 

 the latter was 83 percent. This would indicate that Russian-olive 

 would have to be sown more heavily than honeylocust to achieve 

 stands of equal density. 



An examination of table 4 reveals that species which are dormant 

 because of a thick seed coat generally have higher germination ratings 

 than species with a dormant embryo. The latter, in spite of strati- 

 fication and af terripening, often fail to complete their germination 

 within 30 to 60 days. 



Table 4. — Laboratory germination expressed in percentage of apparent viability 

 of seed based on cutting tests 



Seeds 



Laboratory 

 germination 



Well-filled seed 

 in cutting tests 



Ratio of germina- 

 tion to cutting test 



Basis, 





Range 



Average 



Range 



Average 



Range 



Average 





Medium-to-tall deciduous 

 trees: 



Percent 

 52-58 

 22-31 

 66-92 

 66-92 



Percent 

 54 



127 

 83 

 81 

 49 



139 

 54 



151 

 48 

 44 



57 



63 



79 

 31 



132 

 52 



166 

 47 

 28 

 45 

 32 



139 



Percent 

 92- 98 

 86- 96 

 96- 98 

 97-100 



Percent 

 95 

 92 

 97 

 99 

 95 

 90 

 74 

 90 

 90 

 98 

 76 



74 



99 

 100 



93 

 98 

 86 

 100 

 100 



96 

 85 

 64 



Percent 

 53-62 

 24-37 

 53-97 

 68-92 



Percent 

 57 

 29 

 86 

 82 

 52 

 43 

 73 

 66 

 57 

 49 

 58 



77 



64 

 79 

 33 

 33 

 60 

 66 

 47 

 58 

 47 

 38 

 61 



Number 

 3 



Green ash._ ___ . 



4 



Honeylocust 



Kentucky coffee tree 



Pecan _ 



4 

 5 

 1 



Bur oak _ 









1 







1 







1 



Western soapberry _ _ _ . 



47-56 

 36-57 

 36-56 



47-69 



55-78 

 73-85 

 26-37 

 24-43 

 31-73 

 44-89 



84- 96 

 94-100 

 68- 81 



68- 78 



92-100 

 100 

 90- 96 

 96-100 

 84- 92 

 100 



56-58 

 36-57 

 46-72 



67-91 



55-85 

 73-85 

 27-41 

 25-43 

 37-87 

 44-89 



2 



Osageorange 



Siberian elm 



3 



4 



Conifers: 



Ponderosa pine 



Short trees and shrubs: 

 Siberian pea-tree- .. 



6 

 5 



Redbud. 



2 





2 



Russian-olive 



Tatarian honeysuckle 



Apricot 



'Siberian buckthorn 



5 

 4 

 2 

 1 



Skunkbush. 







1 



Silver buffaloberry. . 



40-51 

 24-40 



93- 99 



82- 88 



43-51 

 27-49 



2 



Common lilac 



2 



Jujube 





1 These values are 10 to 20 percent lower than can be attained under nursery conditions and where the 

 seed has been properly pretreated. 



It is strongly suspected that the method of handling the species 

 which have embryo dormancy can be improved considerably, and 

 that higher germination of these species can be obtained in the 

 nursery by keeping stratification temperatures near 40° to 45° F. with 



