Irrigation, Row Spacing, Plant Growth Regulator and Nitrogen Nutrition Interactions in Short Season Cotton Production

P.W. Tracy and W.P. Sappenfield


 
ABSTRACT

Short season cotton production is dependent on many management inputs. Agronomic research is commonly restricted to one or two variables and does not address the interaction of multiple crop management parameters. The purpose of this research was to monitor several common management practices in the same experimental design to determine the relationship of those practices in efficient cotton production.

Two years of short season cotton production research was done at the University of Missouri, Delta Research Center Lee Farm. The soil type at this location was a Tiptonville fine loamy sand (Fine silty, mixed, thermic Typic Argiudoll). Management practices tested were: irrigated vs non-irrigated, PIX vs no PIX plant growth regulator, 30 inch vs 38 inch row spacings and nitrogen (N) fertilization treatments consisting of 40 pounds N applied preplant (pp), 80 pounds N pp, 40 pounds N pp + 40 pounds N applied sidedress at first bloom (ad) and 40 pounds N pp + 80 pounds N sd. The experimental design was a triple split plot with irrigation as main plots, PIX as sub plots, row spacing as sub-sub plots and N fertilization as sub-sub-sub plots. Four replications of all experimental treatment combinations were tested. Seed cotton yield, lint cotton yield, plant height, physiological growth, petiole N content and ginning quality components were determined for each experimental plot.

Irrigation increased cotton lint yields regardless of other management practices (main effect). Irrigated cotton produced 1271 pounds lint/acre compared to 1198 pounds lint/acre for non-irrigated cotton in 1987. In 1988, irrigated cotton yielded 915 pounds lint/acre compared to 837 pounds lint/acre for non-irrigated cotton. PIX also increased cotton yields (main effect). In 1987, treatments which received PIX yielded 1266 pounds lint/acre compared to 1206 pounds lint/acre in treatments which did not receive PIX. In 1988, PIX treatments produced 904 pounds lint/acre compared to 848 pounds lint/acre in non-PIX treatments. A cotton yield interaction occurred between row spacing and N fertilization. No difference in cotton lint yield was found between 30 and 38 inch row spacing when N fertilization was applied at split applications. However, when all N was applied at 80 pounds/acre pp, the 38 inch row spacing plots produced 117 pounds lint/acre more than the 30 inch cotton plots. This lint yield response was attributed to greater N use efficiency by cotton plants in 39 compared to 30 inch row spacing treatments. Cotton petiole nitrate concentrations were 37%, 55%, 106% and 72% higher for 38 inch compared to 30 inch row spacing treatments for 40 pp, 80 pp, 40 pp + 40 ad and 40 pp + 80 ad pounds N/acre N fertilization treatments, respectively. Plant populations were 27% higher for 30 inch compared to 38 inch row spacing systems. Irrigation did not effect petiole nitrate concentrations. Petiole nitrate concentrations were 14% higher in PIX compared to non-PIX treatments. There were no treatment effects on % lint in either year of the study.

In summary, irrigation and PIX plant growth regulator increased cotton yields during both years of the study. These two management practices appear to be cost effective for short season cotton production in southeast Missouri. The 38 inch row spacing system utilized N more efficiently than did the 30 inch row spacing system and led to greater cotton yields under certain N fertilization regimes. Lower plant populations in 38 inch row spacing compared to 30 inch row spacing management only partially explained higher plant N concentrations found in the 38 inch row spacing system. Water and non-N plant nutrient uptake may also be effected by row spacing. More work needs to be done monitoring cotton growth under the 30 inch system so that management recommendations can be made specifically for that system. This study will be continued in 1989.



Reprinted from Proceedings: 1989 Beltwide Cotton Research Conferences pg. 528
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998