Diosgenin (a steroidal saponin of fenugreek) has long been used as a raw substance for the manufacturing of steroid drugs. In order to evaluate the nutritional effect of different nitrogen (0, 50, 100, 150 and 200 kg ha^-1) and copper (0, 10, 20 and 30 kg ha^-1) doses on the diosgenin content, growth and yield of fenugreek (var. Ardestan), an experiment was carried out in a factorial arrangement based on complete randomized block design. The diosgenin content in the plant was monitored by a high performance liquid chromatography. Lower doses of copper increased yield, yield component and diosgenin content, but its higher level (30 kg ha^-1) had negative effects on the plant yield. The simultaneous application of nitrogen and copper ameliorate the diosgenin production, yield and yield component. The result obtained from correlation and stepwise regression analysis showed that traits such as leaf area index, pods number per plant, and dry weight have significantly direct relation to diosgenin production levels in plants, while dry weight has the highest effect on diosgenin production compared to other traits. According the results, we also can conclude that nitrogen application can decrease copper toxicity in fenugreek in the contaminated soils.

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