Mohammad Nasir, Sharif Ahmed, Md. Mahbub Hassan
Research Associate, Second Crop Diversication Project, Department of Agricultural Extension, Jessore, Bangladesh
PhD Research Scholar, Bangladesh Agricultural University, Mymensingh
Senior Officer, Sonali Bank Limited, Gaibandha, Bangladesh
Key words: Allelopathy, Herbicide, Weed control efficiency, Weed density, Weed biomass.
Over use of herbicide may cause several environmental hazards and development of herbicide-resistant weeds along with high cost. Allelopathy is a component of integrated weed management (IWM) could be potentially used for weed control by producing and releasing allelochemicals. A field study was conducted to evaluate the allelopathic potentiality of Cassia siamea and Gliricidia sepium leaf in controlling weed at the experimental farm of the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur during aman season of 2010. Treatment consists of 11 weed control methods (weedy, weed-free, pretilachlor 1 L a.i. ha-1, fresh leaves of Cassia siamea 2.5, 5, 7.5, and 10 tha-1, and Gliricidia sepium 2.5, 5, 7.5, and 10 tha-1. C. siamea, and G. sepium leaves incorporation effectively controlled weeds; however, higher rate was more effective than lower rate. The highest weed control efficiency (WCE) was recorded from G. sepium 10 t ha-1. WCE of C. siamea 7.5 and 10 t ha-1 and G. sepium 2.5, 5, and 7.5 t ha-1 had similar results to herbicide treatment pretilachlor 1 L a.i. ha-1. Across the rates of leaves incorporation, C. siamea and G. sepium had 14-27 and 8-22% lower yield, respectively, when compared with weed-free treatment. Grain yield increased significantly when C. siamea and G. sepium leaves incorporation rates increased from 2.5 to 10 t ha-1. The results of the study indicates that C. siamea and G. sepium leaf have strong allelopathic potential against weeds and farmers can use fresh leaves of C. siamea around 10 t ha-1 and G. sepium 7.5 -10 t ha-1 to effective control of weeds in transplanted rice.