NURSERY PRACTICE FOR PRAIRIE-PLAINS PLANTING 



33 



adequate moisture content in the stratification medium. It is also 

 believed that the degree of ripeness at the time of collection is an 

 important item in the germination of the seed of species which show- 

 embryo dormancy. 



RELATION OF LABORATORY TO FIELD GERMINATION 



Table 5 shows the relation of laboratory germination to field 

 germination, as determined by Alba H. Briggs of the Prairie States 

 Forestry Project, in 1938, from tests conducted during the 1937 

 nursery season at Fremont, Nebr. The 1937 season was characterized 

 by favorable weather during the germination season and, therefore, the 

 data may at least be considered indicative of what might be expected 

 during an average season under conditions similar to those existing at 

 the Fremont nursery. 



.V study of table 5 reveals that the sowing ratios discussed later in 

 this publication in connection with table 22 can to a large degree be 

 justified on the basis of the variance existing between laboratory and 

 field germination. Briggs explains that this difference represents 

 measurements of two different quantities under different sets of con- 

 ditions; i. e.j laboratory germination tests are a measure of germinative 

 capacity under the controlled ideal conditions in the laboratory, while 

 field results are a measure of emergence capacity under variable 

 adverse conditions of depth of sowing, moisture, temperature, and 

 other factors seldom subject to complete control. 



Table 5. — Emergence capacity in nursery plots expressed in percent of laboratory 



'germination tests 



Species 



Laboratory Emergence 

 germination I in field 

 A sowing's (B) 



B/A 



Medium-to-tall deciduous trees 

 Northern catalpa . 



Green ash 



Honeylocust 



Kentucky coffee tree . 



Black locust 



Osageorange 



Hackberry 



Red mulberry 



Short trees and shrubs: 



Lilac 



Common chokecherry 



Tatarian honeysuckle 



Siberian pea-tree 



Russian-olive 



Perct ni 



Percent 



Percent 



71 



52 



73 



90 



43 



48 



90 



80 



89 



91 



84 



92 



78 



18 



23 



60 



30 



50 



60 



44 



73 



91 



60 



tit; 



37 



16 



n 



30 



8 



27 



52 



5 



111 



80 



62 



7^ 



80 



40 



50 



Summary of Collection and Handling Practices 



For convenience, preferred practices in collection, extraction, storage, 

 and pretreatment of seed, as developed by the Forest Service for tin 1 

 various species, are summarized in table 6. 



297878°— 41 



