Management strategies for optimizing barley yield through row spacing under variable weed competition duration

Knowledge of crop-weed competition dynamics is necessary for implementation of cost-effective weed eradication strategy. To quantify yield loss and estimate critical competition period of weeds in barley (Hordeum vulgare L.) crop, two-year field study was executed at research area, Department of Agronomy, College of Agriculture, University of Sargodha, Pakistan during winter seasons (2016-17 and 2017-18). Treatments comprised of three row spacings viz., S 1 = 15 cm, S2 = 20 cm and S3 = 25 cm and twelve crop-weed competition periods viz., weedy until 14, 28, 42, 56, 70 days and till harvesting and weed free until 14, 28, 42, 56, 70 days and till harvesting. Data indicated significant increases in plant height (5%), number of productive tillers count m-2 (2%), grain count per spike (7%), 1000-grain weight (9%), biological yield (7%) and grain yield (15%) of barley in 15 cm row spacing over the other row spacings. On the other hand, significant reduction in weed dry weight (4%) was recorded in 15 cm row spacing followed by 20 cm and 25 cm row spacings. Means data of both years showed that weed free until harvest had a significant improvement in plant height (20%), productive tiller m-2 (13%), grains per spike (57%), 1000-grain weight (67%), biological yield (27%) and grain yield (50%) compared to weedy until harvest. The logistic model supported the field study results and suggested that critical weed free period (CWFP) and critical time for weed removal (CTWR) for barley to avoid 10% yield losses were 73-74 days and 16-18 days after crop emergence (DAE). The model also predicted that wider crop row spacing resulted an extension of 1 day in in CTWR and CWFP for getting better crop yield while maintaining higher farmers??? earning. To our cognizance, we are the first who established facts regarding the weed competition period under different row spacing???s in barley crop in Pakistan other scientists could avail to develop efficacious weed management plans in other areas of the country.