Effects of Morphological Characters and Bacterial Blight Resistance of Cotton Plants on Bacterial Populations of Raw Cotton Fiber

A.A. Bell and G.W. Tribble


 
ABSTRACT

Total bacterial concentrations and percentages of gram-negative bacteria were determined in raw cotton fiber samples collected from 20 cultivars and lines of cotton grown in the Brazos River Valley near College Station, Texas, in 1986. The cultivars and lines varied in levels of resistance to bacterial blight and in occurrence of mutant morphological characters (glandless, nectariless, frego-bract, okra-leaf, smooth stem, and stormproof boll) known to affect incidences of insect damage and boll rot. The cotton lines were planted in each of four blocks (replications) located sequentially along the length of the field. Between initial boll opening and harvest on November 1, the cotton was exposed to 27 rains of 0.03 inches or greater (11.81 inches total). Analyses of variance indicated that there were no significant (P = 0.05) differences in total bacteria/gm or percentages of gram-negative bacteria among the cultivars or lines, but there were significant (P = 0.01) differences in both among replications. Thus, environment effected bacterial populations more than did the genetics of the plants. In 1987 14 cotton lines with white, tan, brown, and green lint were compared for effects on bacterial populations. The tan and brown colors are due to melanins formed from condensed tannins, and the green color is due to daily deposition of suberin and lignin in the developing fiber. Bacterial numbers/gm were significantly (P = 0.05) increased, approximately doubled, on the brown and green fiber compared to the white fiber of a genetically similar line; tan fiber had no effect on populations. Percentages of gram-negative bacteria were not changed significantly by fiber color. These results indicate that neither tannins, suberins, nor lignins in fiber are effective deterrents of bacterial growth.



Reprinted from Cotton Dust: Proceedings-12th Cotton Dust Research Conference 1988 pg. 23
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998