Abstract:
A study was conducted to determine the allelopathic effect of essential oil from bottle brush (Callisremon lanceolatus DC. ) on seed germination and seedling growth of barnyard grass (Echinochloa crus-galli L.) and spiny amaranth (Amaranthusus spinosus L.). The essential oil at rates of 10, 15, 20 and 25 μl/petridish and 0.625, 1.25, 2.5 and 5 μl/petridish were tested on barnyard grass and spiny amaranth , respectively. A distilled water was used as the control. The results showed that the essential oil at all concentrations decreased seed germination, shoot length and root length. With an increased percentage of inhibitors in accordance with the higher concentration which had the inhibitory percentage in the range of 7.46 - 71.04 % (barnyard grass) and 20.95 - 100 % (spiny amaranth). Natural product herbicide from C. lanceolatus. at concentrations of 100, 200, 400 and 800 ppm and at concentrations of 25, 50, 100 and 200 ppm were bioassayed on seed germination of on barnyard grass and spiny amaranth. The results showed that essential oil products at all concentrations have an effect on seed germination. Growth of the shoot length and root length of both tested plants with a percentage of inhibition increasing according to the higher concentration with the percentage of inhibition in the range of 7.97 - 44.66 % (barnyard grass) and at100 and 200 ppm completely inhibit the growth of Spiny amaranth. The natural product herbicide effect on seed imbibition and α-amylase activities of both plants tested seed were studied. The result showed that seed imbibition and α-amylase activities of both plants tested seed increased by prolonging time whereas decreased with increasing
concentrations. The effect of foliar appiaction of essential oil at conventration of 10000, 20000, 40000 and 80000 ppm (active ingredient) were tested on growth and dry weight of barnyard grass and spiny amaranth. Spray volume wes 80 litters/Rai. The results show that at the highest concentation of 80000 ppm completely inhibited of barnyard grass and highly inhibited spiny amaranth (92.26%).