Manage Crop For Improved Micronaire
Part 1 of 3

This is the first in a series from the National Cotton Council for producers on late-season cotton management aimed at improving micronaire. This first release centers on how high nighttime temperatures can adversely affect both cotton yield and fiber quality.

High Temperatures Hurt Cotton Fiber and Yield

With high nighttime temperatures, respiration increases, which results in a shortage of carbohydrates. During peak bloom, the developing bolls have a high carbohydrate requirement. Increased respiration depletes the plant of these carbohydrates. The plant is forced to ration carbohydrates by adjusting the boll load through boll shed and reduced boll size – resulting in lower yield.

Heat Wave – Negative Effects on Fiber Quality

High temperatures can affect fiber quality, specifically micronaire, in two ways:
Each daily ring of cellulose that is deposited will be thicker, resulting in fibers that are thicker with increased micronaire. Fibers also can be shorter. This can result in a higher concentration of cellulose in the fibers, which will increase micronaire values.

The boll-setting period also can be shortened, decreasing the number of immature late-season bolls with lower micronaire that could have been blended with the older, higher mike bolls. The loss of these top bolls also can result in higher micronaire values.

If the stress from heat or drought is rapid and severe, there may not be enough time to shed all the bolls that canít be supplied carbohydrates. The result will be inferior fiber that has reduced micronaire, strength and potentially shorter fiber.

Management Tips:

Enhance fiber quality by applying enough water.
Make timely irrigation applications.
Avoid drought stress during peak bloom to reduce chances of premature cutout.
Reduce drought stress during first 3 weeks of boll development by watering well.
Make insect control a priority ñ a well-balanced boll set will even out quality variations