Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2019
Publication Date: N/A
Interpretive Summary: Cotton is a high value commodity throughout the world. Several insect pest species can attack the developing cotton fruit (or boll) and reduce cotton yield and fiber quality. The thickness of the boll wall may be instrumental in preventing damage by seasonal pests, but the rate at which the boll wall thickens over time is not known. The objective of this study was to determine boll wall thickness in four cotton species, and varieties within species, at pre-determined boll ages. Boll wall thickness was significantly influenced by age of the bolls, as well as cotton species and varieties within species. One cotton species consistently possessed thicker boll walls than the remaining three species. While wall thickness continued to increase over time once a boll was formed, maximum boll wall thickness was generally observed at 14 d after flower with a gradual decline in thickness thereafter. A similar pattern of maximum thickness at 14 d after flower was observed for cotton varieties within virtually all cotton species. These results aid in identifying those cotton species and varieties that possess thicker boll walls, including rate of wall thickening. These findings provide a foundation for screening cotton resources to potentially select for increased wall thickness as a source of pest resistance.
Technical Abstract: Cotton (Gossypium spp. L.) is a high value cash crop worldwide, and numerous pest insects can attack the developing cotton boll and reduce yields and fiber quality. Thickness of the boll wall may be instrumental in deterring these seasonal pests, but the temporal development, or rate at which the boll wall thickens, is not known. The objective of this study was to determine boll wall thickness in four cotton species (Gossypium arboreum L., G. barbadense L., G. herbaceum L., and G. hirsutum L.), and entries within species, at selected boll ages. Overall, mean wall thickness was significantly affected by cotton species and boll age. Temporal boll wall thickness differed significantly between cotton species as well as among entries within species. When boll ages were pooled, G. barbadense possessed significantly higher mean wall thickness than G. arboreum, G. hirsutum, and G. herbaceum. When cotton species were pooled, maximum wall thickness was observed at 14 d after flower, followed by 21 d, and these were significantly higher than 3, 7, and 28 d after flower. Within all species, temporal differences in wall thickness were observed between entries evaluated, and followed the general pattern of maximum thickness at 14 d after flower. These findings improve our understanding of boll wall development and provide a foundation for screening cotton germplasm to potentially select for increased wall thickness as a source of pest resistance.