Early Season Defruiting Effects on Dry Matter Partitioning in Cotton

W.T. Pettigrew, J.J. Heitholt, and W.R. Meredith


A delay in cotton fruiting is thought to retard the development of some early season insect infestations by depriving the insect population of a food source. However, inconsistent yields have been obtained when early season fruit removal was imposed upon a cotton crop. The objectives of this study were to investigate the effect of early season fruit removal on the pattern and timing of dry matter partitioning and yield in cotton. In 1989, during the growth period when the cotton plants had only produced about 1-2 squares, three treatments, a check, hand removal of squares > 0.5 cm in diameter, and ethephon as a side directed spray, were imposed. Four genotypes, DPL 50 and the normal, okra, and super okra leaftype isolines of MD 65-11 were tested. Height, dry matter, and reproductive structure count data were collected periodically throughout the season. Mapping and yield data were collected at the end of the season. There was no treatment effect on any of the components of vegetative growth, other than a significantly (P<0.05) shorter height for the ethephon treated plants up until 52 days after treatment. Reproductive growth, as defined by flower and boll development, was delayed about ten days with ethephon treatment and only slightly with the hand removal treatment. Although ethephon was successful in moving bolls higher up the plant, no significant treatment differences were found in the total number of bolls or percent infected with boll rot (about 18%) late in the growing season. The check and hand treatments had 50 % more of their total yield obtained by the first harvest (20 Sept.) than the -ethephon treatment, while the ethephon treatment had 20 % more of its total yield obtained on the final harvest (10 Nov.) than the other treatments (P<0.05). Although the average boll size of the ethephon treatment was 5 % smaller (P<0.05) than the check or hand, there were no significant differences in the total yield. For the most part, there were no significant genotype*treatment interactions. The main effects of square removal during the 1989 growing season were to delay the maturity of the crop and shift the bolls higher up the plant.

Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pg. 56
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998