Mohamed Balah - Desert Research Center
Ahmed Sallam - Sohag university
Mohamed Khodary - Desert Research Cnter

Halfa or cogongrass (Imperata cylindrica L.) is one of the noxious/problematic species which not only threatens agriculture productivity, but also causes environmental damage to the ecosystem, whereas the invasive alien weeds are affected greatly by seed germination that depends on the temperature and light as well as other environmental factors. Therefore, the germination behavior of I. cylindrica at the optimum temperature regimes (۲۵/۳۵ °C) was chosen to test the effect of different light regimes, some growth regulators i.e. indole butyric acid (IBA), gibberellic acid (GA۳), and naphthalene acetic acid + naphthalene acetamide (NAA + NAD), and chemical substances i.e. Potassium nitrate (KNO۳) and Si-Si-۶, acetic acid on seed germination of cogon grass (I. cylindrica). The higher germination percent of I. cylindrica seeds was observed after soaking for ۱۲ hours in the growth regulators at ۲۰۰, ۸۰۰, ۴۰۰, and ۱۰۰۰ ppm which exhibited germination of ۵۶.۶۷, ۷۱.۱۱, ۷۳.۳۳, and ۵۶. ۶۷% after soaking in gibberellic acid and ۶۵.۵۶, ۷۱.۱۱, ۷۳.۳۳, and ۵۶.۶۷% after soaking in indole butyric acid, respectively under ۱۶/۸ hours of light/darkness. The maximum germination of I. cylindrica seeds (۲۲.۴۴%) was also achieved after exposure to ۱% acetic acid for ۱min. under ۱۶/۸ h light/ dark and the same temperature, while the greater level of germination (۵۵.۵۶% and ۳۵.۵۶%) was attained after ۱۲ h. soaking in ۱۰% from Si-Si-۶ (Potassium sulphonate ۱۰% SL) and KNO۳, respectively. It can be concluded that I. cylindrica germination rate depends on the environmental factors and its time of exposure which are the driving force for changes in I. cylindrica seed dormancy. This information could help in preventing and predicting their invasion as well as may lead to improving its management strategies.

Halfa or cogongrass (Imperata cylindrica L.) is one of the noxious/problematic species which not only threatens agriculture productivity, but also causes environmental damage to the ecosystem, whereas the invasive alien weeds are affected greatly by seed germination that depends on the temperature and light as well as other environmental factors. Therefore, the germination behavior of I. cylindrica at the optimum temperature regimes (۲۵/۳۵ °C) was chosen to test the effect of different light regimes, some growth regulators i.e. indole butyric acid (IBA), gibberellic acid (GA۳), and naphthalene acetic acid + naphthalene acetamide (NAA + NAD), and chemical substances i.e. Potassium nitrate (KNO۳) and Si-Si-۶, acetic acid on seed germination of cogon grass (I. cylindrica). The higher germination percent of I. cylindrica seeds was observed after soaking for ۱۲ hours in the growth regulators at ۲۰۰, ۸۰۰, ۴۰۰, and ۱۰۰۰ ppm which exhibited germination of ۵۶.۶۷, and ۵۶. ۶۷% after soaking in gibberellic acid and ۶۵.۵۶, ۷۱.۱۱, ۷۳.۳۳, and ۵۶.۶۷% after soaking in indole butyric acid, respectively under ۱۶/۸ hours of light/darkness. The maximum germination of I. cylindrica seeds (۲۲.۴۴%) was also achieved after exposure to ۱% acetic acid for ۱min. under ۱۶/۸ h light/ dark and the same temperature, while the greater level of germination (۵۵.۵۶% and ۳۵.۵۶%) was attained after ۱۲ h. soaking in ۱۰% from Si-Si-۶ (Potassium sulphonate ۱۰% SL) and KNO۳, respectively. It can be concluded that I. cylindrica germination rate depends on the environmental factors and its time of exposure which are the driving force for changes in I. cylindrica seed dormancy. This information could help in preventing and