Abstract: Recoveries of labeled nitrate-N in different soil layers by wheat at different growth stages were investigated with soil column experiment under the controlled irrigation condition. The results showed that recovery and uptake of labeled nitrate-N by wheat at any stage decreased with the increase of depth of labeled-N in the soil profile. The recovery of labeled nitrate-N in 10-20 cm, 40-50 cm, 70-80 cm soil layer were 15.7%, 3.4% and 1.2% at shooting stage, respectively, and the corresponding recovery were 30.6%, 10.7% and 3.9% at earring stage, 33.1%, 13.1% and 5.1% at flowering stage; and 32.5%, 12.4% and 4.7% at maturing stage. Uptake of labeled nitrate-N in 10-20 cm soil layer by wheat almost maximized at earring stage, but the maximum uptake of 40-50 cm and 70-80 cm layers occurred at flowering stage. Recoveries of labeled nitrate-N in different soil layers by wheat were significantly correlated with the root density and its dry weight in corresponding layers.

Key words: Common wheat (Triticum aestivum Linn.), Accumulated nitrate-N, 15N, Recovery of labeled nitrate-N, Root system