Relationship between nitrogen uptake and use efficiency of winter wheat grown in the North China Plain

Abstract

Wheat (Triticum aestivum L.) cultivars with improved nitrogen-use efficiency (NUE) under low and medium N conditions will help to minimise production costs and nitrate-N contamination. The study was conducted to determine the NUE diversities of winter wheat genotypes, and to evaluate the possible physiological mechanisms contributing to these differences. A set of 12 winter wheat genotypes, including S4185 as control genotype, were grown at high N (applied with 180 kg N/ha as urea) and low N (with no N fertiliser, N-deficient) plots in 2005–06 and 2007–08 growing seasons (i.e. four environments). ANOVA showed significant differences among genotypes for all traits measured. Among genotypes, XJ19-1 had significantly higher NUE and N uptake efficiency (NUpE) than S4185 at the two N levels in the 2 years (P < 0.05). KN9204 had significantly higher NUE in the four environments and higher NUpE in three out of four environments than S4185 (P < 0.05). WR9603 and XJ138-1 had higher NUE and NUpE than S4185 in two or three out of four environments (P < 0.05). XJ19-1, KN9204, WR9603 and XJ138-1 also showed higher grain yield (GY) and aboveground dry matter (DM) than S4185 in at least two environments (P < 0.05). KN9204 were 45.7 and 23.1% higher in root dry weight (RDW) of the top 40-cm soil profile compared with J411 at high N and low N plots, respectively (P < 0.05). In addition, there was a highly positive correlation between RDW and grain N yield (GNY) of KN9204 and J411 (P < 0.01). Closely positive correlation between NUE and GY, DM, GNY and NUpE at both N levels in the 2 years (P < 0.01), and between N utilisation efficiency (NUtE) and NUE only at high N plot (P < 0.05) were found. Our results indicated that NUpE was the important factor of NUE under low N conditions, and both NUpE and NUtE were the most important NUE components under high N conditions.