Abstract: In this paper,a field experiment with three genotypes of spring wheat was conducted in Harbin in 2002 to investigate the effects of nitrogen (N) and phosphorous (P) fertilization rate and sowing date on the dynamic changes of grain sedimentation value (GSV) during their grain filling stage.The results showed that the dynamic changes of GSV with the days after anthesis fitted third-order convex curve,and the effects of genotypes and environmental factors on the dynamics of GSV formation could be expressed by the characteristic variables of the curve equation.Different genotypes had different GSV,and the dynamic change shapes in the accumulation velocity curves of GSV were responsible for its mature values.With the increase of N fertilization rate,the GSV and the peak values of its dynamic curves decreased in high protein-rich gluten and low protein-poor gluten genotypes but increased in high protein-medium gluten genotype,and the dates corresponding to the peak values were advanced in high protein-rich gluten genotype while postponed generally in high protein-medium gluten and low protein-poor gluten genotypes.With the increase of P fertilization rate,the GSV and the peak values of its dynamic curves increased generally in high protein genotype but decreased in low protein genotype,and the dates corresponding to the peak values were all postponed in the three genotypes.A rational ratio and rate of N and P fertilization was the key to elevate the GSV during grain filling stage.Under moderate rainfall,the interaction between temperature and sunlight was the predominant factor affecting the dynamic formation of GSV in different genotypes,and rainfall was the second factor.≥10 ℃ accumulated temperature was the most sensitive factor affecting the dynamic formation of GSV because the enhancement of ≥10 ℃ accumulated temperature could elevate the GSV in the three genotypes.In general,high protein genotype was more easily affected by N and P fertilization rate and meteorological conditions than low protein genotype.

Key words: XANES, phosphorus, solid state speciation, application