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Doctoral Dissertations
The yield and uptake of nutrients by selected corn genotypes as influenced by nitrogen fertilization
Date of Award
12-1970
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Plant, Soil and Environmental Sciences
Major Professor
W. L. Parks
Committee Members
G. E. Hunt, J. Q. Chambers, W. T. Smith
Abstract
This investigation was conducted on a Hartsells loam soil to study the effects of nitrogen level and genotype on yield and plant composition of N, P, K, Ca, and Mg at various stages of growth over a three-year period (1966-1968). The experimental design was a split plot with nitrogen levels of 0, 60, 120, and 240 pounds of N per acre constituting the main plot treatments and genotypes constituting the split plot treatments. Leaf tissue samples were taken at thinning, waist high and silking stages. These stages were approximately 38, 55, and 86 days after planting in all three years. Whole stalk samples were taken in 1968 at 110 days after planting. N determinations were made with the Technicon Autoanalyzer on plant samples digested with sulfuric acid and hydrogen peroxide. P, K, Ca, and Mg contents were determined from the nitric-perchloric acid digestate using the Technicon Autoanalyzer. Yields increased with the addition of nitrogen up to the 60 pounds per acre level for the inbreds and up to the 120 pounds per acre level for all other genotypes. Due to a cool, cloudy, and wet growing season, the yields were much lower in 1967 than in the other two years. The calculated N level for maximum yield for the hybrids, based on linear and quadratic regression models, varied from 177 pounds per acre for the Fl's to 199 pounds for the double-crosses. Generally the percent N increased, the percent P and K decreased, and the percent Ca and Mg remained unchanged as the level of applied N increased. The percent composition of N, P, K, Ca, and Mg was much lower at the waist high stage than at the thinning stage. Between the waist high and ear leaf stages the percent content of N and K were further reduced while P and Mg percentages remained more or less constant and the Ca percentage exhibited a definite increase. Genotype was found to affect yields and nutrient accumulation patterns. In many cases the inbreds transmitted their nutrient absorption characteristics to their hybrid progeny. The F1 hybrids removed much more N, P, K, Ca, and Mg in the above ground part of the mature corn plant than did the inbreds. Regression equations involving ear-leaf nitrogen content and genotype proved to be correlated with yields and may be useful in predicting yields. These equations accounted for 69, 49, and 77 percent of the variation in yields of the F1 hybrids, backcrosses, and double-cross hybrids, respectively.
Recommended Citation
Ashburn, Elmer Lee, "The yield and uptake of nutrients by selected corn genotypes as influenced by nitrogen fertilization. " PhD diss., University of Tennessee, 1970.
https://trace.tennessee.edu/utk_graddiss/8021