10 MISCELLANEOUS PUBLICATIONS 1251, U.S. DEPT. OF AGRICULTURE 



Table 3. — Germination, transplanting, and nutrient requirements for selected plants — Continued 







Germination 





Period between seeding in 

 vermiculite and — 



Species ' 



Method 2 



Seeding 

 depth 



Temperature 



Time 



Transplant- 

 ing in 

 nutrient 

 solution 



Applying nutrient 

 solution at — 





One-third 



strength 



One-half 



strength 







Cm. 



°C. 



Days 



Days 



Days 



Days 



Sweetpotato 

 Swiss chard. _ . 



1 

 1 



4 2.5 

 2.5 

 



1.3 

 2.5 

 2.5 

 2.5 

 1.3 

 2.5 



25 

 25 

 30 

 25 

 25 

 30 

 25 

 23 

 30 



5 14 

 6 

 7 

 7 

 4 

 6 

 10 

 6 

 6 



40 

 21 

 21 



21 



14 

 6 

 7 

 7 

 4 

 6 



10 

 6 

 6 



60 

 21 



21 



21 

 21 



Tobacco 



Tomato. 



Turnip.. . 



Wheat 



Wild buckwheat. _ 



1 

 1 

 1 

 1, 2 

 1 



Wild mustard. ... 



1 



Wild oat 



1. 2 







1 See index for scientific names. 



2 Method 1 = vermiculite; method 2 = paper roll (see pp. 8-11). 



3 Rhizome sections. 



4 Tuber or fleshy root. 



5 Shoot emergence from tuber or fleshy root. 



inside the waxed paper, placed in a beaker or 

 jar with 5 em. of water, and incubated at the 

 desired temperature, usually in the dark (fig. 1). 

 The absorbent paper keeps the seeds moist 

 and the waxed paper prevents the toweling from 

 drying out. Generally 4 to 5 days' incubation is 

 required. 



When the seedlings are removed from a dark 

 incubator, they are colorless or etiolated and 

 cannot be exposed to bright illumination without 

 first hardening them for a day in room light (100- 

 200 ft.-c). If the seedlings are directly exposed 

 to sunlight or bright illumination in a growth 

 chamber, the hypocotyl or cotyledons may be 

 damaged and the seedlings may die. For example, 

 it has been our experience that unhardened 

 soybean seedlings become scalded if transferred 

 directly from a dark incubator into a growth 

 chamber with an illumination of 1,600 ft.-c. 

 In contrast, hardened seedlings can be trans- 

 planted and placed in an environment with any 

 required illumination. 



Seed germination by the "paper roll" method 

 may require more time and care than direct 

 seeding in flats. However, distinct advantages 



make the method worthwhile. Seedlings germi- 

 nated by the paper roll method may be selected 

 for uniformity of root and shoot development 

 and may be transferred to nutrient or other 

 solutions with minimum root damage and without 

 particulate matter adhering to them. 



PN-2923 



Figure 1. — Germination of cucumber seed on moist paper 

 toweling. 



