Effect of nitrogen on grain yield, grain protein and agronomic nitrogen use efficiency in winter wheat (Triticum aestivum L.) cultivars

The objective of this study was to gain a better understanding of how Nitrogen (N) affects grain yield and quality of bread wheat genotypes. This experiment was conducted in Agricultural Research Center of Moghan, Iran, with 20 genotypes at three replications and two N levels (0 and 200 kg ha-1), based on RCB-design. Analysis of variation for N was significant (P < 0.01) for grain yield, NUE, grain N content and (P < 0.05) for grain protein yield, Thousands Kernel Weight (TKW), and Bread Volume (B.V). Genotype × Nitrogen (GN) interactions showed significant differences in TKW, grain N content, wet gluten, grain Hardness Index (HI), B.V and Zeleny sedimentation index. Reduction of N cause to reducing of grain yield, agronomic NUE, grain N content, B.V, but it caused increasing of TKW. The highest agronomic NUE has been shown in G2, G5, G17 and G19. Differences in NUE were primarily determined by greater yield, not increased N concentrations in the plant material. Genotypes showed high diversity on bread making quality for all trials. Evaluations of GN interactions, based on wricke equivalent showed one half of variance belong to Zagros, Arta, Darya, Tajan and Akinchi-84 cultivars. Wet gluten observed a positive and significant correlation with Zeleny sedimentation, HI. Cluster analysis classified genotypes in three main groups, Zagros as the sensible, Tajan, Darya and Arta as the semi sensible and other genotypes indicated as stable cultivars. Consume low N rate for stable cultivars especially in fertile ground condition and high N consume rate for sensible cultivars in in-fertile conditions have been recommended.