Allelochemicals Effect of Aqueous Sweet Basil (Ocimum basilicum L.) on Weed Control in Peanut and Cowpea Crops

Four experiments were conducted during 2019 and 2020 summer seasons at Weed Research Central Laboratory, Giza and Ismailia Research Stations, to exploit of the allelochemicals potential of aqueous extract derived from aboveground parts of Ocimum basilicum on controlling some annual weeds and the growth of cowpea and peanut crops. Aqueous extract applied at 40% concentration as pre-emergence and/or apportionment as 30%+10%, 20%+10%+10% and 10%+10%+10%+10% starting at pre-emergence with one week interval for the estimation of effective periods. The main findings showed that essential oils of aerial parts of Ocimum basilicum were 41 compounds which were analyzed by GC-MS. The major compounds were Eugenol, phenol, 2methoxy-3-(2-propenyl), 1,3,6,10-Cyclotetra decate traene, 14-Isopropyl-3,7,11-trimethyl(+), genranyl-a-terpinene, Retinol, acetate, 3-ethyl-3-hydroxy and drostan, 2-(7-hepta decynyloxy) tetrahydro 2h-pyran and M&P-Camphorene. These compounds have allelopathic effect on weeds. On the other hand, Ocimum extract at 40% concentration as pre-emergence was superior over other extract treatments on controlling annual weeds and increasing the growth characteristics and yield of peanut and cowpea plants. Furthermore, Ocimum extract treatment at 40% as pre-emergence was of the same potential of pendimethalin as soil-herbicide at 4.2 l/ha. These results were true in pot and field experiments.