In the Canadian Prairies, many soils on organic farms are low in available phosphorus (P). Previous research has shown that wheat species/cultivars vary in their sensitivity to P deficiency, yield response to applied P fertilizer, P uptake and P use efficiency on P-deficient soils. A 3-year field experiment was conducted from 2012 to 2014 on a P-deficient soil at Kelvington, Saskatchewan, Canada, to determine the potential of five wheat species/cultivars (Spelt and Kamut representing “ancient”, Red Fife representing “old”, and Unity and Goodeve representing “modern” wheat species/cultivars) for seed yield, protein concentration (PC) in seed, partial factor of productivity (PFP, kg seed kg-1 of N applied), total N and P uptake, P use efficiency (PUE, kg seed kg-1 of P applied) and % recovery of applied P in seed under zero-P and with P fertilizer (triple superphosphate) applied at 20 kg P ha-1. Seed yield, PFP and PUE were determined in all 3 years, but PC, total N and P uptake, and % recovery of applied P in seed were determined only in 2012. There was a marked and significant response of seed yield and PFP of all wheat species/cultivars to P fertilizer in all 3 years, but the actual seed yield and PFP, without and with applied P fertilizer, as well as PUE, varied with species/cultivar in different years. On the average of 3 years, seed yield and PFP were greatest for Unity in both without and with applied P fertilizer treatments. Seed yield increases from applied P were 1111, 773, 890, 1810 and 2028 kg·ha-1, respectively, for Spelt, Kamut, Red Fife, Unity and Goodeve. Total N and P uptake were lowest for Kamut and greatest for Unity or Goodeve, in both without and with applied P fertilizer treatments. Percent recovery of applied P in seed was greatest for Goodeve or Unity and lowest for Spelt or Kamut. Protein concentration in seed usually decreased with P fertilizer, and wheat species/cultivars with higher PC in seed usually showed greater reduction in PC with P application. In conclusion, the findings suggest that the “modern” wheat species/cultivars Unity or Goodeve might be more suitable for high sustainable seed yield and total P or N uptake than the “ancient” wheat species Spelt and Kamut or the “old” wheat cultivar Red Fife, especially when adequate amount of P fertilizer is applied to optimize crop production on a P-deficient soil.