Study of stubble allelopathic effects of cool season crops (wheat,barley and rye) on seedling emergence and early growth of sorghum (Sorghum bicolor), corn (Zea mays) and soybean (Glycine max)

In order to evaluation the allelopathic effects of cool season crops stubble on seedling emergence and early growth of sorghum، soybean and corn، an experiment was conducted in seed library research and greenhouse of College of Agriculture، University of Tehran in 2006. The experiment consisted of cool season crops as main plots، four stubble concentrations (5/3، 7/93، 10/55 and 0 (control) g/kg) and three crops (sorghum، soybean and corn) which were factorially assigned to the main plots. The experiment was arranged as a split plot factorial in a completely randomized block design with three replications. All traits (seedling emergence rate، plant height، shoot dry weight، root dry weight and shoot/root ratio) were affected by experimental treatments. By an increase in stubble concentration to 20 g/pot germination، percent of the studied crops significantly reduced. Germination of soybean was the most susceptible trait to allelopathic mater. Rye had the highest allelopathic effects on plant height of the studied crops. Root dry weight of soybean was significantly affected compared with that of corn and sorghum. The increase of stubble concentration led to the highest shoot/root ratio in soybean.