Allelopathic Effects of Iranian Walnut (Juglans regia) On Barley (Hordeum vuIgare), Corn (Zea mays) and Arugula (Eruca sativa) Germination and Growth

In order to investigation the effects of different concentrations of leaf aqueous extracts of walnut on seed germination and seedling growth of barley, arugula and corn, a laboratory experiment were conducted in the Faculty of Agronomy, Islamic Azad University of Isfahan, in 2013. In this experiment, walnut leaf extract including control (distilled water), 25, 50, 75 and 100% were studied to determine juglone sensitivity in three species based on completely randomized design (CRD) with four replications. Chromatography analysis showed that a highest rate of juglone was observed on walnut leaves in August. Increasing concentration of leaf extract lead to continuously decrease in germination percentage and germination rate, root and shoot length and seedling dry weight. Germination percentage of corn and arugula seeds on primary growth stage showed resistant to walnut allelopathy. The lowest germination percentage was observed on barley in %100 leaf aqueous extracts of walnut. Corn and arugula were more sensitive to walnut extracts than barley seeds, however, root and shoot dry weight in barley had no significantly different between treatments. The aqueous extract of walnut did not have a significant effect on germination components of barley, corn and arugula, so that corn and arugula in the early stages of germination and barley in seedling growth showed strong resistance. The insensitivity of the studied species showed that the aqueous extract of Iranian walnut leaves is a strong substance in controlling weeds of these species towards sustainable agriculture.