Absorption, accumulation and distribution of nitrogen in super-highly yielding winter wheat

In order to clarify the characteristics of nitrogen nutrition in winter wheat with yields of above 9000 kg/ha, field experiments were conducted in Gaocheng County, Hebei Province during 2004-2006 Eight winter wheat cultivars: Shimai14, Jifeng703, Shimai12 and Shixin828 during 2004-2005, and Temai1, Shimai12, Shixin531 and Shixin828 during 2005-2006, were used for the experiments. Plant samples were collected at 8 growth stages and the nitrogen contents in different parts of wheat were determined. The results showed that the N contents in the tested parts of wheat were in the range of 0.22%-3.35% (dry weight). The highest nitrogen contents and accumulation were occurred in leaf blades during the early growing period and in grains during the mature period. The total amount of accumulated N in whole plants were in the range of 232.48 to 285.18 kg/ha, the amount of N needed for forming 100 kg of grain yield was in the range of 2.63 to 3.13 kg. Before booting stage, more than 50% of the absorbed N was stored in leaf blades, and in maturity stage, more than 80% of the N was stored in grains in all the cultivars. 68.02%-73.31% of the nitrogen in grains at maturity stage came from the redistribution from vegetative organs. From seedling emergence to erecting stage, jointing to booting stage, and anthesis to maturity stage are important for winter wheat to absorb nitrogen. According to the characteristics of nitrogen absorption and accumulation, it is essential for winter wheat to yield 9000 kg/ha in Hebei Plain that the soil total N be higher than 0.75 g/kg, and the total fertilizing N be about 260 kg/ha.