Irrigation management impacts on cotton reproductive development and boll distribution

Authors: Herritt, Matthew; Thompson, Alison; Thorp, Kelly

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2022
Publication Date: 4/7/2022
Citation: Herritt, M.T., Thompson, A.L., Thorp, K.R. 2022. Irrigation management impacts on cotton reproductive development and boll distribution. Crop Science. 62(4):1559-1572. https://doi.org/10.1002/csc2.20749.
DOI: https://doi.org/10.1002/csc2.20749

Interpretive Summary: Reduced soil moisture is known to negatively impact cotton fiber yield. To better understand how cotton responds to reduced soil moisture cotton plants were grown with varying rates of irrigation during first square to peak bloom, peak bloom to 90% open boll or from first square to 90% open boll. Growth and development of cotton was negatively impacted in canopy levels where most of the lint yield comes when reduce soil moisture occurred from first square to peak bloom. Reductions in the number of squares and green bolls were observed in the lower middle quarter of plants which reducing bolls per plant when 60% irrigation rates occurred from first square to peak bloom. However, the 80% irrigation rate did not lead to reductions in number of squares or green bolls. This could allow cotton producers a 20% savings on irrigation while maintaining similar fiber yields.

Technical Abstract: Cotton provides a renewable natural fiber resource for textile production. To meet increased fiber production demands, US cotton breeders have focused on increasing cotton fiber yields. However, future global climate predictions will require cotton fiber yield increases in conditions which are projected to limit yield. Among future climate predictions is reduced rainfall which has been shown to negatively influence crop growth, development, and yield. Cotton fiber yield is positively related to the number of bolls per plant. Reduced soil moisture has been shown to reduce the number of bolls per plant resulting in fiber yield loss. To better understand how cotton is affected by reduced soil moisture, additional information is required to discern how the number of bolls per plant is affected. Cotton has been shown to preferentially retain and lose bolls at different canopy levels in response to reduced soil moisture. Lower canopy levels tend to retain bolls in response to reduced soil moisture. Better understanding of how irrigation management strategies effect boll distribution could provide valuable information to better inform cotton management decision. To better understand how growth and development of cotton responds to reduced soil moisture a field experiment was undertaken at the University of Arizona’s Maricopa Agricultural Center in 2016, 2017 and 2018. Cotton plant mapping data was obtained and showed the distribution of reproductive structures in response to different irrigation management strategies. Reproductive development and growth were most sensitive to reduced soil moisture treatment from squaring to peak bloom whereas the period from peak bloom to 90% open boll was unaffected by irrigation rates.