Shifts in nitrogen and phosphorus uptake and allocation in response to selection for yield in Chinese winter wheat.

This study assessed changes in nitrogen (N) and phosphorus (P) uptake and partitioning in response to selection for yield in milestone varieties of Chinese winter wheat (Triticum aestivum L.). We established a factorial trial combining 11 nutrient–water regimes with three (2013–14) and five (2014–15) varieties released from 1970 to 2005. Grain yield increased at a rate of 0.46% year–1, with no apparent increase in the uptake of nutrients. Nitrogen harvest index did not change, and P harvest index increased at a rate of 0.15% year–1. Consequently, yield per unit N uptake and yield per unit P uptake increased at similar rates (0.4% year–1) at the expense of nutrient concentration in grain, which declined at a rate of 0.47% year–1 for N and 0.31% year–1 for P. No trends in N nutrition index were found. Selection for yield in wheat increased the yield per unit nutrient uptake at the expense of grain nutrient concentration. Further gains in yield need to be matched by increasing N uptake to maintain grain protein. Dilution of P in grain needs to be considered in terms of the putatively undesirable role of phytate for human nutrition, and the need for P reserves in seed for crop establishment. [ABSTRACT FROM AUTHOR]