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Physiological assessment of foliar imidacloprid treatments on cotton

by Hundley, Leah Nicole

Abstract (Summary)
Previous studies on cotton have shown that some insecticides have plant growth regulator properties. Trimax(imidacloprid) (TRI) is an insecticide introduced by Bayer CropScience. Multiple applications of TRI have been reported to enhance early plant growth and possibly increase yield. The objective of this study was to look at physiological effects of TRI treatments on plant growth, yield and fiber quality of cotton.

A field study was conducted at the Texas Agricultural Experiment Station in Burleson County, Texas under irrigated conditions. The split-plot design included seed treatments as the whole plot and foliar TRI applications (0.11 L TRI ha-1) as the subplots. Seed treatments included an untreated control (UTC), Temik (aldicarb) (TEM), Cruiser (thiamethoxam) (CRU), and Gaucho (imidacloprid) (GAU). Foliar treatments included 0 applications of TRI (UTC), 1 application applied at the 5-leaf stage (1 App), 2 applications applied at 5-leaf stage and 10 days after initial treatment, (DAIT) (2 App), and 3 applications applied at 5-leaf stage, 10 DAIT and 20 DAIT (3 App). High variability in SPAD readings made it difficult to conclude if differences in chlorophyll content existed among TRI applications. Early season observations showed taller plants due to seed treatments. GAU and CRU also showed a trend for being significantly taller than the control. Yield was not significantly affected by seed treatments. All TRI foliar treatments caused numerical increases in yield compared to the control. Box-mapping data also supported this yield trend. Mean boll weight showed the same increase as reflected in lint yield. All TRI applications gave higher numerical mean boll weights than the control at fruiting positions one, two, and three. Three supplemental greenhouse studies were also conducted. Overall, the greenhouse research indicated numerical increases in boll numbers, and in some cases larger bolls. Fluorescence measurements and chlorophyll extractions were also conducted in the greenhouse. The regression equations derived for the correlation between SPAD readings and chlorophyll content were inconsistent between studies.

Many numerical differences and trends were observed throughout all the studies. However, few statistical differences were noted, making it difficult to conclude that these numerical trends will replicate if the studies are repeated.

Bibliographical Information:

Advisor:Cothren, J. Tom; Lombardini, Leonardo; Lemon, Robert

School:Texas A&M University

School Location:USA - Texas

Source Type:Master's Thesis

Keywords:imidacloprid insecticide seed treatment cotton spad chlorophyll fluorescence

ISBN:

Date of Publication:09/30/2004

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