GROWING PLANTS WITHOUT SOIL FOR EXPERIMENTAL USE 



11 



Some precautions to be taken when using paper 

 rolls are as follows: (1) If the seed is too small, 

 the wet paper toweling will seal off the oxygen 

 supply and cause poor germination. (2) Seed 

 may mold if spores are present unless treated with 



a mild fungicide, or the rolls can be checked 

 after 48 hours and the bad seeds removed. (3) 

 Chemicals toxic to certain seeds might be present 

 in the paper and inhibit growth. 



TRANSPLANTING 



When seedlings have been germinated in a paper 

 roll, they can be transplanted easily into nutrient 

 troughs (fig. 2) or individual solution containers 

 (fig- 3). 



When plants are uprooted from vermiculite or 

 soil, some root damage may occur. The plant will 

 continue to transpire and may wilt if little mois- 

 ture can be absorbed by the damaged roots. Wilt- 

 ing can be minimized by reducing transpiration. 

 This can be accomplished by keeping the plant 

 moist, lowering the temperature, and diminishing 

 the airflow around the plants. When uprooted 

 plants are handled in this manner, they can be 

 kept without harm for 12 to 24 hours until trans- 

 planted. Exposing plants to direct sunlight and 

 high temperature immediately after transplanting 

 causes an enormous stress on them. They should 

 be kept at 15° to 21° C. for 48 hours to slow the 

 transpiration rate and to prevent wilting. 



The size, age, and type of plant being trans- 

 planted often determine success or failure. In gen- 

 eral, younger plants are more successfully trans- 

 planted. Selection of uniform seedlings is essential 

 to obtain uniform subsequent growth. The roots 

 should be inserted vertically into the solution or 



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PN-2924 



Figure 2. — Nutrient culture trough: Plastic frame insert 

 with nylon screen bottom, metal cover, and stainless-steel 

 trough with drain (top to bottom). 



PN-2925 



Figure 3. — Corn and pea seedlings growing in aerated 

 nutrient solution, with capillary tubing (0.25 mm.) in- 

 serted into air line for each culture jar. 



vermiculite without bending or leaving them ex- 

 posed. A little extra care at the time of transplant- 

 ing will give improved results throughout the 

 growing season. The transplanting medium such 

 as soil or vermiculite should be saturated with 

 water or dilute nutrient solution to restore the 

 moisture that the plant may have lost. Care must 

 be taken not to have the nutrient solution too con- 

 centrated when transplanting directly into it, or 

 salt injury and desiccation may occur. It is advis- 

 able to increase the concentration of the nutrient 

 solution gradually as the plant grows. If seedlings 

 are transplanted to containers of vermiculite 30 

 cm. or more in diameter, some of the nutrient salts 

 are adsorbed on the vermiculite and are not avail- 

 able to the plant. This can be avoided by using a 

 slightly stronger nutrient concentration. 



If transplanting into specialized containers is not 

 required, seed may be planted directly into pots 

 with vermiculite and grown in that manner. 



