Absorption,Accumulation and Distribution of Zinc in Highly-Yielding Winter Wheat

Zinc (Zn) is an important essential microelement for wheat. In order to study the characteristics of Zn absorption,accumulation and distribution in highly-yielding winter wheat (with a grain yield of 9 000 kg ha-1), field experiments were conducted in Gaocheng County of Hebei Province, China. Four winter wheat cultivars, i.e., Shimai 14, Jifeng 703, Shimai 12, and Shixin 828, and four cultivars, i.e., Temai 1, Shimai 12, Shixin 531, and Shixin 828, were used in the experiment, during 2004-2005 and 2005-2006, respectively. Plant samples were taken from the plots at each growing stage for Zn concentration analysis. The main results showed that the concentration of Zn in various above-ground organs of wheat was 9.5-112.5 mg kg-1 at different growing stages. The organ with the highest Zn concentration differed with the change of growth center at different growing stages. Accumulation of Zn in leaf blades was the highest among all the organs during early growing period, and more than 50% of the Zn accumulation was distributed to leaf blades before jointing, and higher than that to other organs. In late growing period, however, the accumulation of Zn in grains was the highest, and 58.1% of the Zn accumulation was distributed in grains at maturity. The total accumulation of Zn in wheat plant during its life span ranged from 384.9 to 475.9 g ha-1. The amount of Zn required for the formation of 100 kg grain yield ranged from 4.3 to 5.2 g. All the organs were ordered in such a sequence that leaf blades > spikes > leaf sheaths > stems according to their net absorption and transportation of Zn as well as their contribution to Zn accumulation in grains. 58.2-60.3% of the Zn accumulated in grains was redistributed from other organs, mostly from leaf blades. Concentration and accumulation of Zn in all the organs of wheat was high during early and middle growing periods, while accumulation of Zn in grains during late growing period mainly depended on the redistribution from other organs. According to these characteristics of Zn absorption and accumulation, Zn should be applied as seed dressing or basal fertilizer, so as to accelerate the early growth and Zn absorption of wheat.