Phytotoxic Effects of Basil (Ocimum basilicum L.) Aqueous Extract on Seed Germination of Some Cereal Crops

Abstract

Several plants are phytotoxic in nature as they produce and release many chemical compounds into the environment. This study was carried out to investigate the phytotoxic effects of the aqueous extract of aboveground parts of basil (Ocimum basilicum L.) 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.  Laboratory experiments were carried out at the Faculty of Agricultural Sciences, University of Gezira, Sudan during the season 2017/2018. Ten concentrations (4.62, 9.26, 13.87, 18.51, 23.12, 27.74, 32.36, 36.98, 41.61 and 46.28 g/l) of the aqueous extract of aboveground parts of basil were prepared from the stock solution (100 g / l). A control containing sterilized-distilled water was included for comparison. Treatments were arranged in 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      (P £ 0.5). The aqueous extract of aboveground parts of basil inhibited the seed germination of the tested cereal crops and there was direct positive relationship between concentration (g/l) and inhibition (%). Also, the result showed that the seeds of maize were most sensitive to the aqueous extract of aboveground parts of basil followed by the seeds of millet, wheat and sorghum. The LC₅₀ for maize, wheat, millet and sorghum was 34.1, 46.3, 46.7, and 59.1, g/l, respectively. It was concluded that the aqueous extract of aboveground parts of basil had toxic effect to the seeds of the tested cereal crops

Keywords: basil, cereal, Ocimum; maize, millet, phytotoxic, probit, sorghum, wheat.