Masters Theses

Date of Award

8-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

William E. Hart

Committee Members

Fred D. Tomkins, Mike Bushermohle

Abstract

Effects of tillage practices, row spacings, and application of the growth regulator PIX®̳ mepiquat chloride) on cotton lint yields were evaluated in a three year study conducted in West Tennessee. Average yield difference between no-tillage and conventionally tilled plots was 73 pounds per acre for the 1992 through 1994 season. This significant yield difference was to the advantage of no-tillage production system. Although no-tillage consistently produced higher yield, there was no recognizable year interaction. No yield advantage was found for either 30- or 40-inch row spacings. Average yield difference over the study between row spacings was 3 pounds of lint per acre. However, in any given year, effectiveness of a particular row spacing appeared to be dependent upon the nature of the growing season. Application of PIX®̳ significantly resulted in positive lint yields, the average advantage of using PIX®̳ was 93 pounds of lint per acre. This positive effect of PIX®̳ was influenced by growing season. Further, the positive effect of PIX®̳ application was more pronounced in 40-inch rows than 30-inch row spacing. Maturity of plots was not significantly affected by row spacing on average for the three year study. Tillage, however, did have a significant effect on earliness, with no-tillage plots exhibiting greater maturity. PIX®̳ treated plots also displayed a maturity advantage over untreated plots for the experiment, the magnitude of this advantage of applying the growth regulator PIX®̳ was dependent upon the nature of the growing Season. Plants in 30-inch row spacing measured two inches shorter than plots planted in 40-inch row spacing. Application of the growth regulator PIX®̳ resulted in plants averaging six-inches shorter than plants not treated. Other treatments did not show significant effect on plant height. Canopy closure was significantly affected by row spacing and application of growth regulator PIX®̳ in the 1994 production season. Thirty-inch rows closed canopy 9.3 days earlier than 40-inch row spacing. Average time for closure in PIX®̳ -treated plots was 81.5 days after planting, compared to 78.8 days after planting for untreated plots. No significant effect was found from tillage.

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