Table 2.

Nitrogen partial factor productivity (PFP) and protein yield efficiency (PYE) of common wheat, spelt, durum wheat, emmer and einkorn. PFP is calculated as ratio of kernel yield (in decitonnes (dt) per hectare (ha), i.e., 10,000 m²) and quantity of nitrogen fertilizer (in kg of nitrogen (N)). PYE is calculated as ratio of protein yield, which is the product of protein content (in %) and kernel yield, and quantity of fertilizer. Kernel yield, quantity of nitrogen fertilizer and protein content are means over all cultivars at all four locations within the wheat species.

Wheat Species	PFP	Kernel Yield (dt/ha) 1	Nitrogen Fertilizer	Protein Content	PYE
Unit	(dt/kg × N)	(dt/ha) 1	(kg × N/ha) 1	(%)	(t/kg × N)
Common wheat	0.7	79.8	115	9.6	0.67
Spelt	0.7	50.4	75	11.3	0.76
Durum wheat	0.5	60.9	115	12.5	0.66
Emmer	1.2	36.2	30	11.1	1.34
Einkorn	0.9	26.9	30	11.6	1.04

¹ As reported by Longin et al. [1].