Genotype and ploidy variations influence cottonseed size, oil, protein, and crude fiber content

Authors: Bai, Fang; Bellaloui, Nacer; Feng, Chunda

Submitted to: Journal of the Mississippi Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: This study explores how genetic differences between diploid and tetraploid cotton influence seed size and nutritional quality. Cottonseed is a valuable byproduct of cotton production, supplying oil, protein, and fiber, and its composition is central to its suitability as livestock feed. Tetraploid genotypes generally produced larger seeds, as reflected in both seed index and surface area measurements, while diploids consistently produced smaller seeds. These size differences were also linked to compositional trends. Tetraploid lines tended to have higher oil content, with the genotype AR9317-26 achieving the highest percentage. In contrast, diploid genotypes frequently showed higher protein concentrations, exemplified by CIM 432, which recorded the highest protein value. Fiber content varied widely but showed little consistent association with ploidy, instead reflecting genotype-specific influences; for example, the diploid A2-101 exhibited the highest fiber concentration. Correlation analyses confirmed positive relationships between ploidy and seed size, as well as between seed size and oil content. Conversely, fiber content showed strong negative correlations with both oil and protein. These findings illustrate the complementary strengths of diploid and tetraploid groups and provide insight into breeding strategies aimed at improving both yield and seed nutritional quality.

Technical Abstract: Cottonseed is an important byproduct of cotton cultivation because of its oil, protein, and fiber content in cottonseed meal. Cottonseed meal is used as feed for livestock, and its quality is determined by its content of oil, protein, and fiber (seed composition). Effects of cotton genetics, especially in diploid and tetraploid cotton, on cottonseed composition and quality is still not understood. Therefore, the objective of this project is to investigate seed morphological and compositional traits across 38 cotton genotypes, including 3 diploids (Gossypium arboreum) and 35 tetraploids (Gossypium hirsutum) genotypes. A furrow irrigated experiment was conducted in 2024. The results showed that seed size, measured by the 100-seed weight (seed index), ranged from 5.91 g to 11.51 g. Diploid genotypes consistently produced smaller seeds (5.91–7.85 g), while tetraploids exhibited greater variation (7.66–11.51 g), with CIM 432 genotype displaying the largest seeds. Seed surface area followed a similar pattern, with diploids showing lower values (69.70–91.96 mm²) compared to tetraploids (91.81–134.61 mm²). Seed composition also varied widely. Oil content ranged from 15.79% to 23.31%, with tetraploids generally outperforming diploids, exemplified by AR9317-26, which recorded the highest oil percentage (23.31%). Protein content varied from 22.20% to 30.37%, with diploids showing relatively higher values than most tetraploids; CIM 432 reached the maximum protein content (30.37%). Fiber content ranged from 10.09% to 19.29%, with no clear ploidy-based distinction, although A2-101 (diploid) had the highest value (19.29%). Correlation analysis revealed strong positive associations between ploidy and seed size traits, as well as between seed index and oil content, while fiber content showed strong negative correlations with both oil and protein. These findings highlight the impact of ploidy and genotype on cottonseed size and quality and contribute towards breeding strategies targeting yield and cottonseed nutritional qualities.