Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Plant and Environmental Science

Committee Chair/Advisor

Sruthi Narayanan

Committee Member

Michael Jones

Committee Member

Todd Campbell

Committee Member

Sachin Rustgi

Abstract

Cotton production worldwide is challenged by variability in soil moisture, particularly in rainfed production systems. Sustaining cotton productivity under limited water requires understanding both above- and belowground mechanisms contributing to water use efficiency (WUE). Root system architecture (RSA) and morphology are critical for improving water and nutrient capture and maintaining plant productivity. This dissertation examined beneficial root traits associated with WUE in upland cotton by evaluating a core collection of the U.S. cotton diversity panel under greenhouse and field conditions. The specific objectives of the research were to: (1) characterize the cotton core set for root morphological traits and WUE; (2) identify root-related mechanisms that enhance WUE; and (3) determine the genetic regulation of beneficial root traits that improve WUE and cotton performance. Under controlled environmental, well-watered conditions, WUE was positively correlated with fine root length, surface area, volume, and total root weight with correlation coefficients ≥0.45. Further field evaluations revealed that optimized root distribution in the soil profile, involving deep rooting under dry soil conditions and fine root proliferation under adequate moisture, enhanced cotton biomass, WUE, and yield. Genotypes with greater deep root allocation during the dry year (28–60% of the total root length in 42–57 cm) generally showed superior WUE, biomass production, and yield, highlighting the importance of adaptive RSA for drought resilience. The identified adaptive genotypes included Acala 5, Paymaster HS26, PD 2164, Paymaster HS200, Tidewater 29, and Western Stormproof, among which PD 2164 and Acala 5 demonstrated the highest level of RSA plasticity. Genome-wide marker analysis identified SNPs associated with root distribution across soil depths and fine-root production, with candidate genes involved in root development and stress-responsive pathways. Though these marker-trait associations require validation in larger populations and functional studies, they provide promising genomic targets for improving adaptive RSA plasticity and drought resilience in cotton.

Additional Files
OmPrakash_Appendices_Tables.xlsx (78 kB)

Author ORCID Identifier

https://orcid.org/my-orcid?orcid=0009-0005-7206-2352

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Available for download on Tuesday, August 31, 2027

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