Root inhibition was also employed as an additional biological assay using cucumber seeds (variety i'vIarketer) as the test material. Seeds were germinated at room temperature (approximately 250 C) under laboratory conditions of alternatingf light and darkness on filter paper impregnated with a 0.005 -M solution of the compounds in Petri dishes. Four days after treatment the length of the primary roots was measured (table II), and root length was used as an index of growth inhibition. The roots that appeared from treated seeds were without root hairs. As was the case in the previous experiment, the chlorine substituted benzimidazoles were the most active. (14) found citric acid in barley seeds and in green barley seedlings. In 1931 Nelson and Mottern (11) reported several organic acids in barley and oat, but they used mature green plants, not seedlings, for their investigations. While the research reported here was in progress, Elliott (6) demonstrated by means of paper chromatography the presence of citric, fumaric, glycolic, malic, malonic and succinic acids plus traces of cis-aconitic and a-ketoglutaric acids in etiolated barley seedlings. Using paper chromatography, MIeiss (9) found only citric and malic acids plus an unidentified acid in etiolated white lupine seedlings. Only citric acid was shown to be in the ungerminated seed. Several organic acids have been identified in peas which have grown beyond the seedling stage (13, 17) and indoleacetic and pyruvic acids have been found in etiolated seedlings (1, 17). Citric acid has been reported in the ungerminated seed (10).
LITERATURE CITEDThe present study is a survey of the normal distribution of non-volatile organic acids in seeds and etiolated and green seedlings of barley, oat, white lupine, and pea.Extracts of the ungerminated seeds and of the aerial portions of five-to seven-day-old seedlings of the following species and varieties were chromatographed: Hordeum vulgare, var. Oderbrucker (barley), Aventa sativa, var. Clinton (oat), Lupinus albus (white lupine), and Pisum sativum, var. Alaska (pea). In order that a quantitative comparison could be made between extracts, all chromatograms were made 1 Received April 2, 1955. with a volume of the extract equivalent to 10 mg dry weight of tissue. The percent moisture was obtained by drying the tissues at 1000 C for at least 48 hours.Seeds were ground in a Wiley mill and then extracted with 90 % ethanol. Aerial portions of seedlings were first frozen in a dry ice-acetone mixture and then extracted with 90 % ethanol in a Waring blendor. After removal of the ethanol-insoluble material by filtration, the extract was diluted with two volumes of water. The solution was passed through an IRA-400 resin column to adsorb organic acids and anions (3).
