Critical Crop - Weed Competition Period and Yield Loss Determination in Transplanted Tomato (Lycopersicon esculentum M.) at Guder Ethiopia

Abstract

A field experiment was conducted for two consecutive cropping seasons of 2013 and 2014 to determine the critical period of weed competition and yield loss in tomato at Guder, Ethiopia. Quantitative series of both increasing duration of weedy and weed free periods were compared with complete weed free and weedy check. The experiment comprised of fourteen treatments laid in a randomize complete block design (RCBD) with three replications. The experimental site was infested with different weed species belonging to different families. In 2013 cropping season, 11 weed species belonging to 9 families were identified. Among the identified species, 81.81% were broadleaf weeds whereas sedges and grass made up 9.09% and 9.1% respectively. In 2014 cropping season the experimental site was infested with 12 different weed species belonging to 8 different families. Eighty three percent were broad leaved weeds while the remaining 8.33 % and 8.33 % were sedges and grass weeds, respectively. Pooled data revealed that, Amaranthus spp, Amaranthus hybridus L., Bidens pilosa L., Commelina benghalensis L., Datura stramonium L., Guizotia scabra (Vis.) Chiov., Galinsoga parviflora Cav., Ipomea cariocarpa and Nicandra physalodes Scop were among the predominant broadleaved weeds, whereas Digitaria abyssinica (A. Rich.) Stapf and Cyperus esculentus L. were the common grass and sedge weeds respectively. Significant differences in density, weed dry biomass, tomato yield and relative yield loss were observed in both years. Unweeded plots resulted in a yield reduction of 87.5 in 2013 and 90.8% in 2014 when compared to the yield recorded in weed free condition. Results indicated that to prevent greater than 10% yield loss, the maximum time for which weeds could be allowed to grow after crop transplant was 30 days, and the crop must be free of weeds from 60-75 days after transplanting to prevent a predetermined level of yield loss.