Mother Nature plays a big role in cotton fiber quality characteristics, but farmers' preplant and in-season management decisions may decrease the effects of factors beyond their control.
Variety selection, planting date, fertility, irrigation rate and timing, insect control, weed management, and judicious use of harvest aids offer opportunities to protect quality, said J.C. Banks, Oklahoma Extension cotton specialist, Altus, Okla.
Banks detailed management factors that affect cotton quality at the opening session of the Beltwide Cotton Conferences in New Orleans.
Banks said stress creates an environment that may reduce cotton fiber quality characteristics. “Often a cotton is planted when the weather is too cool, and then it suffers water and nutrient stress during the season, followed by cool weather during maturation. We cannot eliminate stress, so it is to our advantage to make management decisions to reduce its consequence.”
Banks said the first consideration is variety. “Cotton variety selection affects quality more than any other factor,” he said. Selecting the proper variety for each location should be the first step in managing for quality. But other parameters also influence quality and may be influenced by in-season management decisions.
He said growers should understand the cotton development timeline. “Fiber length develops from one day prior to bloom until 16 to 18 days following bloom. After this, the plant starts increasing thickness or micronaire of the fiber and this continues until 40 to 45 days after bloom.”
A cotton plant will hold a number of bolls in various stages of development.
Banks said variety plays a role in fiber length, but environmental conditions are more important.
“Fiber length is sensitive to water stress, and if stress occurs during the lengthening process, fibers will be shorter. Timely irrigation is essential. In dryland production, conservation tillage, reduced plant populations and adequate weed control to reduce competition for available water are key.”
Banks said potassium also affects fiber length. “We need to monitor phosphorus as well as nitrogen and potassium.”
Environment is the greatest threat to micronaire. Banks said heat and stress combine to cause high micronaire cotton. “Heat and stress late in the fruiting period results in loss of small bolls that contribute to lowering the average micronaire. In a worst case scenario, high stress during fiber elongation may result in both short staple and high micronaire cotton.”
Banks said managing to avoid micronaire discounts is difficult because it is so closely related to environment.
“Avoid stresses that cause excessive fruit shed late in the effective fruiting period. Irrigation, cultural systems, weed and insect control can all contribute to decreasing the chances of sudden stress late in the fruiting period.”
Interactions between plant growth regulator applications and nitrogen availability during early bloom may redirect growth from vegetative to reproductive, increasing boll set on the plant. “Excessive deep nitrogen will increase the need for late-season plant growth regulator application, which will increase fruit set even further,” Banks said.
“The plant will be producing at full capacity and will be susceptible to any type of stress. When cutout occurs, it can be severe with loss of immature bolls, and when carbohydrate flow resumes, it will go to developing bolls that were stressed during fiber elongation and will start developing higher-than-normal micronaire.”
That situation could result in short fiber and high micronaire but perhaps a high yield.
Banks recommends testing both topsoil and subsoil to determine total nitrogen available to the plant and applying nitrogen according to a realistic yield goal.
“Use PGRs early to mid-season to insure good fruit set but allow depleting nitrogen to slow the plant late in the season.”
He said insect and weed control may affect leaf and color. “Poor weed control or escapes can contribute to higher leaf readings. And poor control of boll-feeding plant bugs can result in discolored lint.”
Banks said newer varieties, especially the transgenics, may offer higher yield potential, but they also increase the load on the plant, making it more vulnerable to stress.
“Put those high-yielding varieties on the best soils,” he said.
Banks said growers have to decide if higher yields or higher quality will be more important.
The efforts have not always paid off, said Gary Adams, vice president of economics and policy analysis, National Cotton Council, but as international markets increasingly demand higher-quality fiber and an increasingly large percentage of U.S. cotton goes into the world market, growers cannot afford to neglect quality issues.
“Growers select varieties based on the bottom line,” Adams said. “Yield, quality and production costs play important roles.”
In the past, he said, a grower with higher yield and lower quality would make more money than if he had higher quality and lower yields. “But we can't lose sight of customers' needs for better grades.”
He said newer varieties offer high yields and better quality traits. “But will buyers pay for quality? That depends on availability of the cotton they are looking for.”
He said demand now is for 31-3-35, which may offer a premium of 5 cents per pound over a 41-4-34.
Lint quality matters to the customer, it matters to the marketplace and it matters to the bottom line of the grower. It can be the difference between profit and loss.”
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