Allelophatic Effects of Orange Peel Extract on Amaranthus hybridus L. and Pennisetum glaucum (L.) R.Br.

Abstract

Weed control constitutes one of the biggest challenges in modern agriculture. Weed affects crops directly by competing for the limited resources thereby causing deficiency diseases and indirectly by housing pathogens and insect pests. The current control measures involve using synthetic herbicides which are believed to cause more harm than good to the environment. The way out is to resort to alternative bio-based herbicides, which are chief and eco-friendly. Consequently, this research investigated the potentials of orange peel crude extract in controlling both grasses and broad-leaved weeds. Orange peel was extracted using cold maceration methods in two separate solvents – water and methanol – and then divided into three concentrations. The allelophatic effects of these concentrations were tested against Amaranthus hybridus and Pennisetum glaucum. The results revealed that orange peel extract is effective in inhibiting germination and growth in the test plant. Fifty (50) % aqueous extract inhibited germination of A. hybridus and P. glaucum by 80 and 70% respectively, while 50% methanol extract inhibited germination of A. hybridus and P. glaucum 13% and 60% respectively. In addition, the treatments has reduced the seedling survivability with time. There was significant effects of the treatment on growth parameters of the test plants. Furthermore, the treatment has significantly affected the overall seedling vigour of the test plants. Fifty (50) % aqueous extract had the least seedling vigour in A. hybridus, while 30% of the same extract produced the least vigour in P. glaucum. The overall results indicated that aqueous extract of orange peel is more effective in inhibiting germination and growth of the test plants.