Abstract:
Several agro-forestry trees may have the ability to retard germination and growth of other plants by releasing many chemical substances into the environment. This study was carried out investigate the phytotoxic effects of the leaves aqueous extract of Eucalyptus camaldulensis Dehnh on seed germination of sorghum (Sorghum bicolor [L.] Moench), millet (Pennisetum glaucum [L.] R. Br.), maize (Zea mays L.) and wheat (Triticum vulgare L.) using probit analysis. A laboratory experiments were carried out at the Faculty of Agricultural Sciences, University of Gezira, Sudan in season 2014/15. Ten concentrations (4.44, 8.89, 13.33, 17.78, 22.22, 26.66, 31.11, 35.55, 40.00 and 44.44 g/l) of the leaves aqueous extract of Eucalyptus were prepared from the stock solution (100 g / l). A control with sterilized-distilled water was included for comparison. Treatments were arranged in a completely randomized design with four replicates. The seeds were examined for inhibition (%) in germination at three days after initial germination. Collected data were transformed using Abbott’s formula and subjected to probit analysis procedure (P £ 0.5). The results revealed that the leaves aqueous extract of Eucalyptus inhibited the seed germination of the tested cereal crops and there was a direct positive relationship between concentration (g/l) and inhibition (%).The results also revealed that the seeds of wheat were most sensitive (LC50 = 18.7 g/l) to the leaves aqueous extract of Eucalyptus followed by the seeds of sorghum (LC50 = 21.3 g/l). However, the extract was less toxic to the seeds of millet (24.1 g/l) and maize (25.9 g/l). It was concluded that the leaves aqueous extract of Eucalyptus had a toxic effect on the seeds of the tested cereal crops.
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