Cotton boll formation and fiber quality when grown alongside perennial groundcover crops

Authors: Billman, Eric; Sansbury, Sarah; Campbell, Benjamin

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2025
Publication Date: 9/12/2025
Citation: Billman, E.D., Sansbury, S.H., Campbell, B.T. 2025. Cotton boll formation and fiber quality when grown alongside perennial groundcover crops. Crop Science. 65(5). Article e70160. https://doi.org/10.1002/csc2.70160.
DOI: https://doi.org/10.1002/csc2.70160

Interpretive Summary: Cover crop use in U.S. cotton production lags behind that of other major commodity crops due to increased production costs and management requirements, and cover crops providing few immediately visible benefits to producers. Additionally, the downstream effects growing cover crops on cotton boll development and fiber quality are poorly understood. Recent research conducted by USDA-ARS research scientists in Florence, SC sought to alleviate these barriers to cover crop adoption in cotton by investigating the use of perennial cover crops that only need to be established once, thus minimizing time, labor, and monetary inputs required to manage cover crops. Over two-years scientists found that cotton fruiting density was increased in the lower canopy and more second position bolls were formed when cotton was grown alongside perennial red and white clovers compared to either fallow or conventionally managed annual cover crops. Cotton plants also formed fewer secondary vegetative shoots when grown alongside perennial red and white clovers, thus ensuring more plant energy was focused on boll development. Presence of perennial clovers also increased cotton seed size which has been shown to directly boost seedling vigor. Lastly, all major fiber quality metrics were unchanged by growing cotton alongside perennial cover crops, and fewer short fibers were observed under that practice compared to fallow and conventionally managed annual cover crops. These findings show that cotton production can benefit from the use of perennial cover crops, and that these perennial cover crops can help improve the adoption of cover crop practices that reduce input costs to U.S. cotton producers.

Technical Abstract: The incorporation of perennial groundcover crops (PGCC) into cotton (Gossypium hirsutum L.) systems may provide similar benefits to annual cover crops with fewer associated costs, but their effects on boll production and fiber quality have not been investigated. This study assessed the effects of growing PGCC species on boll formation, canopy architecture, and fiber quality compared to annual cover crops or fallow systems. Over two years, cotton was interseeded and grown in four cover crop treatments: 1) terminated weedy fallow, 2) terminated annual ryegrass (Lolium multiflorum Lam.), 3) a living 1:1 mix of perennial red clover (Trifolium pratense L.) and white clover (Trifolium repens L.), and 4) a living 2:1:1 mix of ryegrass, red clover, and white clover. Post-harvest plant mapping was conducted on plants from outside of harvested rows in each plot to determine final boll set, position, and canopy distribution as well as sympodial and monopodial branching. Fiber quality was also assessed via high volume instrument (HVI). Results indicated that the presence of clovers increased boll density lower in the canopy while also increasing the number of position 2 bolls compared to the fallow system, and that growing perennial clovers alongside cotton reduced formation of monopodial shoots. Presence of perennial clovers also reduced the incidence of short fibers in cotton under drought conditions, but did not alter any other fiber quality parameters. These findings further support the use of PGCC as a mechanism to improve adoption of cover crops in cotton production.