Author : Nguyen Vinh Truong

Summary : Five experiments (4 laboratory and 1 field) were conducted at the University of the Philippines Los Baños, Central Experimental Station from May to September 2001 to (a) determine the metalaxyl (Apron 35XL) concentration, length of soaking, and volume of solution for soaking of mungbean (Vigna radiata (L.) Wilczek) seeds that would promote growth and early development of the root system of mungbean; and (b) evaluate the effect of the chemical on the growth and weed competing ability of the crop at different levels of weed control and nitrogen fertilization. Metalaxyl is commonly utilized in agriculture as a fungicide. Mungbean var VN 94-208 soaked in 400 ppm metalaxyl for 12 hours produced significantly longer primary roots and greater number of secondary roots at 5 days after sowing (DAS) under laboratory conditions. However, metalaxyl had no effect using mungbean var PAG-ASA7 seeds. Although metalaxyl enhanced primary and secondary root growth of mungbean in the laboratory when measured at 5 DAS, the chemical did not significantly increase the grain yield, pod number, number of seeds per pod, 1000-seed weight, plant height, leaf number, branch number, nodule number, shoot-root ratio, and seed nitrogen composition when grown in the field. Furthermore the use of the chemical in the field did not improve the competing ability of the crop as shown by data on weed density and weight.