INHIBITION OF PLANT GROWTH BY EMANA- 

 TIONS FROM OILS, VARNISHES, 

 AND WOODS 



By ROBERT L. WEINTRAUB i 



AND 



LEONARD PRICE 



Division of Radiation and Organisms 

 Smithsonian Institution 



(With Eight Plates) 



While attempting to culture oat seedlings in a tightly closed growth 

 chamber constructed from ponderosa pine and hardboard (Masonite 

 Tempered Presdwood)," a very marked retardation or arrestment 

 of development was observed. Inasmuch as the plants were not in 

 direct contact with the growth chamber and as normal seedling de- 

 velopment was found concurrently in a variety of other containers 

 under identical conditions of temperature, humidity, light, and sub- 

 strate, the inhibitory effect seemed to be attributable to an emanation 

 from the box. Production or liberation of the active agent was found 

 to continue over a long period of time as inhibition resulted consis- 

 tently, in undiminished degree, in several trials over a period of some 

 months, despite repeated and prolonged ventilation of the chamber. 



This observation seemed to be of sufficient interest to warrant fur- 

 ther exploratory experiments on various aspects of the phenomenon. 



DESCRIPTION OF PLANT RESPONSE 



Air-dry "seeds" planted on a moist germination substrate ^ and 

 placed at once in the box imbibed water readily and development 



1 Now with the Department of the Army, Camp Detrick, Frederick, Md. 



2 The inside dimensions of the box were 91 X 38 X 36 cm., giving a volume 

 of approximately 124,000 cm.^. The area of the inner pine surface was 9,200 

 cm.2, and of the inner Presdwood surface 6,900 cm.^, or a total of 16,100 cm.^. 

 Prior to use, the interior of the box had been brush-coated with two layers of 

 varnish and allowed to dry thoroughly. 



8 Porous silica wicks (obtainable from Filtros Incorporated, East Rochester, 

 N. Y.) wrapped in filter paper and partially immersed in distilled water con- 

 tained in finger bowls, as illustrated in plate I, were used in most of the ex- 

 periments. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 107, NO. 17 



