Master of Science (MS)
Plant Pathology and Crop Physiology
Greenhouse and microplot studies were conducted to evaluate the influence of soil texture on reproduction and pathogenicity of Rotylenchulus reniformis (reniform nematode) on cotton. A 45 day duration greenhouse experiment confirmed the pathogenicity of an isolate of R. reniformis from Avoyelles Parish on Stoneville LA887 cotton. A series of greenhouse experiments were conducted with three geographic isolates of R. reniformis (identified as Avoyelles, Evangeline, and Rapides to indicate the Parish of origin) on Stoneville LA887, Stoneville 5288B2F, and Phytogen 375WF cotton growing in soils with varying textures for 60 days. Soil types with sand, silt, and clay contents ranging from 74.4 to 7.8, 20.7 to 66.3, and 4.9 to 25.9, respectively, were employed in this research. Two experiments were conducted with Stoneville LA887 cotton, three soil types and Avoyelles isolate of reniform nematode for 150-152 days in a microplot environment. In the greenhouse, variations in soil texture significantly affected plant height and dry weights in both Stoneville 5288B2F and Phytogen 375WF, but did not have any significant effect on plant growth of Stoneville LA887, except in the 45-day duration experiment. Stoneville 5288B2F plants were significantly taller throughout the experiment in soil with 31.4% sand and 13.3% clay. Phytogen 375WF cultivar showed the same pattern, but the difference in plant height was not observed at harvest. Stoneville 5288B2F and Phytogen 375WF had significantly reduced dry root and shoot weights in sandier soils. Soil type had a significant effect on nematode reproduction on all three cotton cultivars. The interaction between soil type and reniform isolate significantly affected population densities of all reniform isolates tested among the multiple soil types in the cultivars Stoneville 5288B2F and Phytogen 375WF, but no effect was observed in Stoneville LA887 cultivar. In the microplot, plants growing in soil with more clay content had significantly greater root and shoot weights than the others. The number of bolls open and seed cotton weight were significantly reduced by R. reniformis in the microplots. Population densities of R. reniformis in the microplot followed the same pattern observed in greenhouse experiments.
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Xavier, Déborah Magalhães, "The influence of Commerce silt loam soil texture on reproduction and pathogenicity of Rotylenchulus reniformis on cotton" (2013). LSU Master's Theses. 145.