Browsing by Author "Keith Edmisten, Committee Co-Chair"

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    Improving Cotton Production Margins through Management Decisions and Use of New and Standard commercial Products to Improve Quality and Profits
    (2005-09-09) Nuti, Russell C; Randy Wells, Committee Co-Chair; David Jordan, Committee Member; Alan York, Committee Member; Art Wollum, Committee Member; Keith Edmisten, Committee Co-Chair
    Cotton (Gossypium hirsutum L.) is a perennial plant managed as an annual crop to optimize yield and fiber quality while managing inputs to maximize profit. Transgenic improvements have simplified cotton production. Resistance to the non-selective herbicide glyphosate and in-plant production of Bacillus thuringiensis (Bt) endotoxin are two such advances. Cultural practices including use of mepiquat chloride (MC), and optimizing planting date contribute to crop uniformity and decrease risk involved with environmental stresses. Comparisons between conventional and transgenic weed and insect management systems, optimal and late planting dates, overhead sprinkle irrigation and drip irrigation, and use of MC were evaluated. Optimal-planted cotton had better yield than cotton planted late. Mepiquat chloride did not always provide an advantage, however never caused an undesirable response. At times, cotton plants treated with MC showed improved micronaire, compensation for boll loss, and earlier maturity. Broadcast glyphosate at the eight-leaf stage reduced yield of optimal-planted cotton in 1 of 3 years and 2 of 3 years in late-planted cotton. Glyphosate contact after the four-leaf stage in 2 of 3 years shifted the majority of bolls above node 10. Lint yield results were variable between overhead sprinkle and drip irrigation systems. Mepiquat chloride did not affect yield in irrigated cotton, however did control plant height, and improve fruit retention and cotton maturity. Non-labeled glyphosate applications reduced maturity in each irrigation system in 1 of 3 years. Cotton injury caused by conventional herbicides resulted in yield loss and poor returns compared to glyphosate systems. Early-season weed competition from low input herbicide programs caused cotton biomass reduction. High costs of conventional herbicide programs offset the available profit margin compared to glyphosate systems when yields were similar. Glyphosate systems provided excellent control of all weed species, while conventional herbicides gave acceptable control in most cases. Glyphosate resistant cotton cultivars with had better yield and returned more profit than the same cultivars treated with conventional herbicides.
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    Investigation of Cotton Growth: Temperature and Carbohydrate Dynamics
    (2003-09-23) Viator, Ryan Patrick; Keith Edmisten, Committee Co-Chair; Randy Wells, Committee Co-Chair; David Jordan, Committee Member; Judith Thomas, Committee Member; John Wilcut, Committee Member
    Research involving NAWF monitoring determined the last effective boll population for ultra-narrow row cotton (UNRC) compared to conventional cotton (CONC) grown in the northern rain-fed production region. The UNRC produced the majority of seedcotton plant-1 on the upper portion of the plant, NAWF 3-5, while CONC produced the most seedcotton plant-1 at NAWF 3-7. Boll numbers showed a similar pattern. The UNRC produced more seedcotton on an area basis at NAWF 2, 3, 4, and 6. Research on heat unit accumulation revealed that single variable models were somewhat related to boll fill period in terms of regression fits, with degree-days 30/13°C providing the best adjusted R2 of 0.9399; the degree day 15.5°C model had an adjusted R2 of 0.9268. Modifying the DD15.5 model by adding either minimum air temperature or maximum and average air temperature increased the adjusted R2 to 0.9632 and 0.9934, respectively, while also reducing mean square error and coefficient of variation. The root and stem carbohydrates study revealed cultivar differences for starch concentration at both sample times, but starch content was only significant at first bloom in 2002. These differences, though, did not show a strong relationship with year of cultivar release, indicating that a century of breeding efforts has not altered stem and root starch dynamics.