Allelopathic effects of Mikania cordata on forest and agricultural crops in Bangladesh

Abstract

Mikania cordata, an invasive weed is becoming a problem in the secondary degraded forests and plantations of Bangladesh, not only competing with but also releasing allelochemicals to cultivated crops. Allelopathic effects of the leaves of M. cordata were investigated through an experiment in the green house of the Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh. Five economically important agricultural crops (Oryza sativa L., Triticum aestivum L., Vigna sinensis L., Abelmoschus esculentus L. and Amaranthus tricolor L.) and three forest crops (Acacia auriculiformis A. Cunn. ex Benth. & Hook, Albizia procera (Roxb.) Benth., and Paraserianthes falcataria (L.) Nielson) were used as bioassay species. Experiments were conducted on trays at an average room temperature 27 °C. The effects of different concentrations of leaf extracts were compared to controls. Water soluble allelochemicals of M. c ordata inhibited the germination and initial growth of the tested agricultural and forest crops. Germination percent of forest crops declined with increasing concentration of extracts. The inhibitory effect on root elongation of forest crops was pronounced, whereas a stimulatory effect was found on P. falcataria up to a concentration of 25 %. Abelmoschus esculentus showed poor germination (%) and low shoot development (0.5 cm) and no development of taproot or lateral roots at treatment of 100 % concentration. The inhibitory effect was proportional to the concentrations of the extracts with higher concentrations producing stronger inhibitory effects. Lower concentrations showed some stimulatory effect. The inhibitory effect was pronounced in root and lateral root development rather than germination or shoot development of the crops. Mikania cordata should be eradicated for healthy growth and development of the forest and adjacent agricultural crops.