Absorption,accumulation and distribution of phosphorus in winter wheat under super-highly yielding conditions

In order to clarify the characteristics of phosphorus absorption,accumulation and distribution in winter wheat cultivated under super-highly yielding(≥9000 kg/ha) conditions,a field experiment was conducted in Gaocheng County,Hebei Province from 2004-2006.Four winter wheat cultivars,Shimai 14,Shimai 12,Jifeng 703,and Shixin 828 in 2004-2005 crop year,and four cultivars,Temai 1,Shimai 12,Shixin 531 and Shixin 828 in 2005-2006 crop year,were selected as experimental materials.The growing area for each cultivar is 1 hectare,and is divided into three subplots of 3333 m2 as three replications.Plant materials were collected from the plots at each growing stage for phosphorus concentration determination in laboratory.The main results show that the concentrations of phosphorus in various above-ground organs,and the total accumulation amounts of phosphorus during the growing period for different wheat cultivars are different,but usually insignificant,showing similar characteristics of phosphorus nutrition for different cultivars with the yield 9000 kg/ha or higher.The concentrations of phosphorus(P2O5,the same as follows) in various above-ground organs of wheat are in the range of 0.25% to 2.32%(dry weight).The organs with the highest phosphorus concentration are different during the growing and development process,leaf sheaths at early period,stems and spikes at the middle period,and grains at the late period.For almost all cultivars,the highest accumulation amounts of phosphorus are in leaf blades at the early growing period,but in grains at the late period among all above-ground organs.At the pre-booting period,the phosphorus absorbed by wheat plants is mainly distributed in leaf blades,where the distribution percentage is more than 50% for most cultivars.At maturity,however,the distribution percentage of phosphorus in grains is more than 60% for all cultivars,higher than those in other organs.Under the conditions of the super-highly yielding cultivation and yield levels of this study,the highest total accumulation amounts of phosphorus in above-ground organs of wheat during its life span are ranged from 110.8 to 151.4 kg/ha,and the phosphorus amounts needed for the formation of 100 kg grain yield are ranged from 1.25 to 1.66 kg.The period with the highest phosphorus absorption is generally from erecting stage to anthesis,and then pre-winter seedling period.This demonstrates that the pre-winter period and the period from erecting stage to anthesis are the key periods for phosphorus absorption.According to the characteristics of phosphorus absorption and accumulation,phosphorus should be applied as basal dressing,so as to accelerate the early growth and phosphorus absorption of wheat.