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This article in AJ

  1. Vol. 62 No. 1, p. 32-36
     
    Received: June 9, 1969
    Published: Jan, 1970


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doi:10.2134/agronj1970.00021962006200010011x

Adventitious Roots, Tillers, and Grain Yields of Spring Wheat as Influenced by N-P Fertilization1

  1. A. L. Black2

Abstract

Abstract

Factorial combinations of concentrated superphosphate at rates of 0, 22, 45, 90, and 180 kg/ha of P and ammonium nitrate at rates of 0, 45, and 90 kg/ha of N were broadcast on a Williams loam soil and incorporated with a tandem disk just before seeding spring wheat (Triticum aestivum L., ‘Fortuna’).

Samples of roots and tops taken at the end of tillering revealed that most of the effect of P and N-P fertilization was accounted for by changes in plant morphology. Tillers per plant (T) were positively correlated with adventitious roots per plant (R), [T = 1.21 + 0.23R, r3 = 0.96]. Heads per ha (H) were linearly related to adventitious roots per plant (R), [H = 1.99 + 0.24R, r3 = 0.94], and to tillers per plant (T), [H = 0.89 + 1.00T, r3 = 0.88]. Number of heads per ha accounted for 97% of the yield variance associated with fertilizer treatments. Number of kernels per head and kernel weights were not significantly influenced by N and P fertilization. The regression of grain yield on number of adventitious roots per plant accounted for 93% of the variations in grain yield associated with fertilizer treatments.

Grain yields increased from 1984 to 2706 kg/ha (29.5 to 40.2 bu/A) when 45 kg/ha of P was added alone and to 3306 kg/ha (48.2 bu/A) when 45 kg/ha of N was also applied. Higher rates of P, with or without added N, failed to further increase grain yield.

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