Effect of Blooming Date on Boll Retention and Fiber Properties in Cotton1
- Laval M. Verhalen,
- Reza Mamaghani,
- Walter C. Morrison and
- Ronald W. McNew2
Six cultivars of upland cotton (Gossypium hirsutum L.) were studied to determine the influence of blooming date on boll retention and selected fiber properties in experiments conducted over 3 years at a single location. Flowers were tagged at weekly intervals; and after frost, bolls within plots were harvested by tagging dates. Records were kept by dates of blooms tagged/row, tagged bolls set/row, and percent tagged bolls set/row. Fiber properties (2.5% span length, 50% span length, uniformity index, micronaire, and 1/8-inch gauge stelometer) were also studied to determine their patterns of variation.
In general, blooms tagged increased from the beginning of the flowering season until shortly after mid-season, then declined to form a fairly symmetrical distribution. Boll set increased rapidly during the first 3 weeks of the season, then gradually decreased. Percentage boll set was highest at the first of each season, then declined fairly continuously. As a consequence, shedding rate increased in a linear fashion as the seasons progressed. In one instance, it appeared that the cotton plant exhibited increased boll retention efficiency when blooms were limited. The 2.5 and 50% span length measurements exhibited similar distributions within each of the 3 years; however, both showed moderately different patterns between years. Their means did decrease fairly steadily, particularly during the latter part of each season. Evidence in 1 year suggested that about a week's delay was required to obtain a response in the longer fibers comparable to that in the shorter ones. Uniformity index was higher at the end of each season than in midseason; and in 2 of ~ years, it was also higher at the first of the season. All cultivars except one displayed lower micronaires at the end of the flowering season than at the beginning. The 1/8-inch gauge stelometer reading also declined toward the end of the flowering period.
Relative performance among cultivars for each trait and their differential response patterns over the season are discussed in the text.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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