New cotton grading system to help farmers with planting best seeds for soil

One of the most common row crops in Arkansas has one of the most mysterious origins. No one knows exactly when humans first started using cotton to make clothes.

Scientists have found bits of cotton in Mexican caves that date back more than 7,000 years, according to the National Cotton Council of America. Cotton was widely used in ancient Egypt and in the Indus River Valley civilization in Pakistan. When Christopher Columbus arrived in the Bahamas in 1492, natives were growing cotton.

Cotton has been grown in Arkansas since the early 1800s and was mostly grown in the southwest part of the state. That changed after the Civil War when large swaths of swamplands in the Arkansas Delta were drained exposing nutrient-rich soils, according to the Encyclopedia of Arkansas. Cotton farming became so prevalent in the region that Mississippi County was the top cotton producing county in the country.

The days of million-plus cotton acres in a growing season seem to be in the past, but the crop made a comeback last year.

Arkansas cotton acreage jumped more than 27% in 2024 to 650,000 acres, a growth rate consistent with the United States cotton industry as a whole. The state also saw a record average yield of 1,313 pounds per acre, for an overall production estimate of 1.75 million bales. Cotton prices remained low in 2024, falling from the 2023 average of 79 cents per pound to 76 cents.

Acres don’t have to increase for more cotton to be grown in the state, and the way to do it is yield improvements. Professor Fred Bourland with the Arkansas Agricultural Experiment Station is developing a third cotton grading score for farmers.

Grading scores can help farmers determine what seed varieties perform best in their soil.

The 50-year veteran has already developed the Q-Score for fiber quality and the S-Score to characterize optimal seed and lint indices into a single index.

The Yield Component Score, or YC-Score for short, represents how much a cotton variety favors lint production relative to seed production to produce lint yield.

“If the cotton line has a high YC-Score, then it’s relying more on lint per seed rather than seed per acre, which is more favorable because the production of lint requires less plant energy than the production of seed,” Bourland said.

Cotton lint yield is equal to the number of seeds per acre multiplied by the weight of lint per seed. Lint yield may be improved by increasing either seeds per acre or the weight of lint per seed.

Bourland noted the latter is more efficient because it requires less plant energy to increase yield and has a higher heritability. In other words, cotton breeders can more easily carry lint per seed characteristics forward through variety selection.

Bourland is working in partnership with Cotton Incorporated to release an app for breeders to calculate the YC-Score.

The YC-Score app is made possible after 20 years of documenting cotton lines that have a higher lint index relative to seeds per acre. Bourland said the program was validated by having a strong association between the objective YC-Scores generated by the program and the subjective yield component rating generated by his team for cotton lines in different tests and years. Criteria included lint yield, seed per acre and lint index.

The YC-Score app is still under development but is expected to be released by Cotton Incorporated in the coming year, along with an associated publication.

Analyzing their high-performing varieties, breeders may use the YC-score to differentiate those that produce lint more efficiently, which should lead to high yield stability. Bourland explained that as a general rule, lower yielding lines often have high yield stability, but breeders want to identify lines that produce high yields and rely more on lint index than on seed per acre.

“The way the app works is that you find lines that are good yielding, then see how they’re getting their yield — that’s what the YC-Score will tell you,” Bourland said.