@article{klein_blum_1990, title={EFFECTS OF SOIL-NITROGEN LEVEL ON FERULIC ACID INHIBITION OF CUCUMBER LEAF EXPANSION}, volume={16}, ISSN={["0098-0331"]}, DOI={10.1007/BF01021033}, abstractNote={It has been suggested that the allelopathic activity of phenolic acids should be primarily important in soils of low fertility. If this is true, then plant growth inhibition by phenolic acids may be unimportant in managed agricultural soils. The objective of this study was to determine how soil nitrogen (N) level might modify phenolic acid inhibition of growth. Cucumber seedlings (Cucumis sativus cv Early Green Cluster) grown in containers in growth chambers under varying N levels (5, 10, 15, 20, and 25 μg N/g soil) in Portsmouth B,-horizon soil material were treated with ferulic acid (0 or 10 μg/g soil). Nitrogen and ferulic acid (FA) were applied every other day to the soil surface. The amount of FA in the soil solution declined with depth in the containers. A more rapid disappearance of FA from the soil solution was observed for the last FA treatment (0% recovered after 10 hr on day 23) than the first treatment (44% recovered after 10 hr on day 13). Both low N (5 μg N/g soil) and FA treatments reduced shoot dry weight, the mean absolute (AGR) and the mean relative (RGR) rates of leaf expansion, and increased the root-shoot ratio. High N treatments reduced shoot dry weight and the AGR. Ferulic acid inhibited cucumber seedling growth over a range of N concentrations, suggesting that the allelopathic activity of phenolic acids may be important in both nutrient limiting and nonlimiting soils for some species.}, number={4}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={KLEIN, K and BLUM, U}, year={1990}, month={Apr}, pages={1371–1383} }
 @article{klein_blum_1990, title={INHIBITION OF CUCUMBER LEAF EXPANSION BY FERULIC ACID IN SPLIT-ROOT EXPERIMENTS}, volume={16}, ISSN={["0098-0331"]}, DOI={10.1007/BF01021777}, abstractNote={Experiments were conducted to determine how the proportion of a root system in contact with an allelopathic compound may affect seedling responses. Cucumber seedlings grown in a split-root nutrient culture system were given either single (1 mM) or multiple applications (0.5 mM) of ferulic acid. Seedlings receiving single applications were left in the treatment solutions for two days and then harvested, while seedlings receiving multiple applications had their solutions changed every other day for a total of three changes. Leaf areas were determined daily starting with the initial ferulic acid treatment. Mean absolute and mean relative rates of leaf expansion were inversely related to the proportion of the root system in ferulic acid solution. Leaf expansion was inhibited primarily during the first 24 hr after each treatment. A partial recovery of growth occurred during the second 24-hr period following each treatment. Root length was reduced by ferulic acid. These results suggest that information on root and allelochemical distribution in soils is important when assessing the potential of allelopathic interactions between plants.}, number={2}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={KLEIN, K and BLUM, U}, year={1990}, month={Feb}, pages={455–463} }