Adventitious Roots, Tillers, and Grain Yields of Spring Wheat as Influenced by N-P Fertilization1
- A. L. Black2
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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