Masters Theses

Date of Award

3-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

William L. Parks

Committee Members

Gary M. Lessman, John G. Graveel

Abstract

Dekalb 747 and Pioneer 3147 corn hybrids were grown on a Sequatchie fine sandy loam (Thermic Humic Hapludult) in a Randomized Complete Block with a split-split plot arrangement of treatments in 1983 and 1984. The experiment was conducted to investigate the effect of row spacing, plant population, and nitrogen on yield, evapotranspiration, and water use efficiency.

In 1983 and 1984 the yields for both hybrids were significantly increased (P=.05) when row spacing was decreased from 38- to 30-cm rows. In 1983 the yield of Dekalb 747 was significantly increased when the nitrogen rate was increased from 220 to 280 kg*N*ha-1 but nitrogen rates did not effect the yield of either hybrid in 1984. Altering plant population did not effect the yields of either hybrid in 1983 or 1984.

The 1984 yields of Dekalb 747 in 51- and 61-cm rows were significantly higher than from 76-cm rows, but these row spacings did not effect yields of Pioneer 3147. Significantly higher yields of Pioneer 3147 were obtained at all row spacings with 280 kg*N*ha-1 .

Evapotranspiration data were collected for both hybrids in 1983 and 1984. In general there was no significant effect on evapotranspiration due to treatments. In 1983 both hybrids showed a peak water use period during the tasseling stage and the evapotranspiration rates generally decreased after this stage. The absence of the peak water use period in 1984 may have been due to the high frequency of rainfall In the early part of the growing season which resulted in runoff that was not accounted for in the evapotranspiration calculations.

Water use efficiency of either hybrid was not significantly affected by plant population in 1983 or 1984. In 1983 row spacing did not effect water use efficiency of the Dekalb 747, but significantly increased water use efficiency of the Pioneer 3147 as the row spacing was decreased from 38- to 30-cm rows. In 1984 water use efficiency of Dekalb 747 was significantly increased when row spacing was decreased from 38- to 30-cm rows, while row spacing did not have an effect on water use efficiency of Pioneer 3147. Row spacings of 51", 61-, or 76-cm did not significantly effect water use efficiency of either hybrid in 1984.

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