ESTIMATION OF ECONOMIC THRESHOLD OF Convolvulus arvensis L. WEED IN WHEAT (Triticum aestivum L.)
Weed economic threshold in a specific crop serves as a tool for employing its cost-effective management. Studies were carried out to find out competitive effect of field bindweed (Convolvulus arvensis L.) on wheat at research area of College of Agriculture, University of Sargodha, Pakistan during winter season 2014-15. Experimental treatments included varying densities (0, 4, 8, 12, 16 and 20 plant m-2) of Convolvulus arvensis. The weed densities were maintained by thinning the excess weed seedlings one week after crop emergence. Wheat variety Galaxy was sown as a test crop. Results exhibited that increasing densities of C. arvensis increased its dry weight m-2 but reduced its plant height. A significant reduction in wheat growth and yield was recorded by increasing C. arvensis density. Wheat plant height, number of productive tillers, spike length and grain yield showed a significant decline at and beyond C. arvensis density of 8 plants per m2. Whereas number of grain spike-1 and 1000-grain weight of wheat were prone to substantial reduction at and above 4 and 12 C. arvensis plants m-2, respectively. Losses of grain yield of wheat ranged between 10 to 28% under the influence of C. arvensis density between 8 to 20 plants per m2. Economic threshold of C. arvensis as estimated by prediction model was 5.6 plants per m2 indicating that field bindweed weed in wheat should be controlled at this density.