The paper deals with evaluating the yield and yield structure elements of winter durum wheat lines (Triticum durum Desf.) under conditions of varied levels of chemical protection. The field experiments were carried out in 2006-2008 on the Experimental Farm Felin, University of Life Sciences, Lublin. Examinations involved 3 lines of durum wheat (STH 716, 717, 725) achieved from Plant Breeding Station in Strzelce as well as common wheat Tonacja cv. for comparison. The second factor consisted of 2 levels of chemical protection: I – minimum (seed dressing Oxafun T 75 DS/WS and herbicide Chwastox Trio 540 SL); II – complex (seed dressing, herbicides Puma Uniwersal 069 EW and Chwastox Trio 540 SL, fungicide Alert 375 SC, growth regulator Stabilan 750 SL and insecticide Decis 2,5 EC). Obtained results allowed for concluding that when comparing with minimum protection, the increase in wheat grain yields by 1.08 t·ha^-1 was recorded on complex-protected treatments, regardless of compared lines and varieties. Lower yield of durum wheat as compared to common wheat resulted first of all from lower spike density per area unit. A positive influence of chemical protection on spike number and grain number per spike was observed. Durum wheat lines were characterized by high grain vitreousness.

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