8HIROSE T,WERGERM J A.Maximinsing daily canopy photosynthesis with respect to the leaf nitrogen allocation patternin a canopy[J] .Oecologic ,1987 , 72:520- 526 .
9MOLL R H,KAMPRATH E J,JACKSON W A.Analysis and interpretation of factors which contribute to efficiency of nitrogen utilization[J] .Agron J,1982 , 74: 562 - 568 .