Nitrogen Translocation in Wheat Plants Under Soil Water Deficit

Accumulation and translocation of nitrogen (N) in the vegetative organs and grains of winter wheat (Triticum aestivum L.) are important processes in determining yield and quality. The present study was conducted to compare the effects of water deficit and cultivars (cv. Lumai 21 and Jinan 17) on N translocation from vegetative organs to grains in a mobile rain-shelter using ¹⁵N-labeled ammonium sulfate fertilizer. The N translocation amounts (defined as the difference between the N amount at anthesis and the N amount at maturity for a vegetative organ) in leaves were greatest for the two cultivars, followed by glumes, stems, and sheaths, respectively. The N translocation ratio (defined as the ratio of the translocation amount to N amount at anthesis) in total above-ground parts were greater for Lumai 21 (0.65 g g⁻¹ DW) than for Jinan 17 (0.60 g g⁻¹ DW), and Lumai 21 plants had a higher N translocation ratio for the N derived from fertilizers. The N contribution (defined as the ratio of the translocation amount to grain N amount) of total vegetative parts aboveground to grain N ranged from 0.50 to 0.77 g g⁻¹ DW, and that of the leaf was the greatest. The results showed that water deficit remarkably increased the N translocation ratio derived from soil and the contributions of N in various vegetative organs to grain N. It is suggested that water deficit would weaken the availability of fertilizer N but enhance the remobilization of prestored N to the grains.