Abstract: 【Objective】Freeze injury in wheat often happens and affects wheat yield formation during the wintering stage. There was less study on the remedial measures to recover wheat yield after low temperature stress at wintering stage. Hence, effects of remedial fertilizer after low temperature stress on yield recovery in wheat at tillering stage and its mechanism were studied, which will provide a basis for anti-cultivation technology in wheat. 【Method】The spring wheat cultivar Yangmai16 was treated at -2℃/-6℃(day/night, 2012) and -2℃/-8℃ (day/night, 2013) for 24, 48 and 72 h, respectively, using artificial temperature-controlled phytotron system. Then the different remedial urea (N 46%) amounts of 75, 150 kg·hm^-2 (2012) and 75, 120, 180 kg·hm^-2 (2013) were all used at a time after low temperature stress. The degree and freezing injury proportion of wheat plant under low temperature stress and the changes of soluble sucrose, proline and endogenous hormone contents in the second leaves from the top on the 10th, 20th and 30th day after applying remedial fertilizer were investigated. Plant height and yield at maturity were also recorded. 【Result】The index of freezing injury increased from 0.2 to 0.5 under longer stress at tillering stage. The contents of soluble sugar, proline, abscisic acid (ABA) and zeatin riboside (ZR) in leaves of the treatment increased under longer stress. These parameters in the treatment without fertilizer amendment were higher than those in the treatment with fertilizer amendment on the 10th day after applying remedial fertilizer. The parameters reduced more rapidly with more applying fertilizer under the same duration time. The content of gibberellines (GA₃) decreased gradually with longer stress at tillering stage. The contents of soluble sugar and proline, and the contents of ABA and ZR of these treatments using fertilizer after cold stress gradually declined on the 20th day after applying remedial fertilizer. While the change of GA₃ contents was opposite to ABA and ZR contents. All these parameters reached the levels of the controlled plants in natural environment on the 30th day after applying remedial fertilizer. Wheat yield, the first and second basal internode length and plant height all lowered with longer cold stress. With increased fertilizer applying amount under the same treatment duration, the length of wheat plants were better restored and the loss of grain yield was lessened.【Conclusion】Cold injury wheat will recover growth after using the right urea amount scientifically in time depending on the cold index at tillering stage. Osmotic adjustment substance contents declining and hormone contents becoming balance, new tillers emergency and the basal internode length becoming longer were the main reason for increasing grain yield at tillering stage after applying the urea. At tillering stage, considering recovery effect and nitrogen partial factor productivity, 75 kg·hm^-2 urea would be recommended for nitrogen amendment when wheat plants were damaged slightly and the cold index was about 0.2. When the cold index was about 0.36, 120 kg·hm^-2 urea would be suggested. When the cold index was about 0.50, 180 kg·hm^-2 urea was recommended for recovering wheat growth after severe cold damage.

Key words: wheat, tillering stage, cold injury, remedial fertilizer, regulation effect