Development of Active Root System Architecture of Upland Cotton for Improved Sub-surface Water Uptake During Drought Conditions

View the project final report

Commodities

• Agronomic: cotton

Practices

• Crop Production: plant breeding and genetics, water management

Irrigation can be a short-term solution to water scarcity. For many areas of the world, long-term irrigation use can be unsustainable for cotton agriculture. Cotton typically has some drought tolerance; however, the inability to easily phenotype the root system architecture (RSA) has resulted in elite cultivars with reduced growth and plasticity in root systems. To explore cotton’s phenotypic variation of RSA in the germplasm, 660 accessions from around the globe were narrowed down to 200 accessions for RSA phenotyping analysis. Four seed companies each contributed three of their elite cultivars to this research. The accessions were simultaneously grown in the greenhouse and field locations. The greenhouse evaluated baseline RSA under well-watered conditions. The field tested the accessions under drought stress and compared the RSA of seven accessions. The rainfed condition of West Texas during the 2024 summer season allowed sufficient drought stress to affect most of the accessions significantly. A minimum of fifteen accessions had no significant difference between the irrigated and rainfed conditions. Many accessions also had a more robust RSA with higher root length, greater root-to-shoot ratio, and finer average diameter. A pattern of thicker primary root diameter, but finer lateral roots, performed better under drought conditions, along with a higher root length and a higher root-to-shoot ratio, which contributed to performing better under drought conditions. Using the phenotypic data of this study will allow for genetic associations to be completed, and identification of potential genes involved in the RSA will help future research and breeders develop cotton accessions that can integrate the benefits of an increased RSA for drought tolerance. 

Objective 1)

Identify a subset of Upland cotton accessions (175-200) and elite commercial cultivars (15) by selecting from the 600 accessions grown in the greenhouse.

Objective 2)

a) Evaluate the root system architecture (RSA) of the diverse germplasm using an image-based root phenotyping platform under controlled greenhouse conditions. The plants will be grown in the greenhouse for about 2 weeks before scanning their RSA with the scanner and software program. b) Select a subset of the five most promising and the five least promising of the exotic accessions in addition to the control and elite cultivars for contrast. To evaluate the RSA traits, under well-watered and water-deficient treatments in field conditions, three replications will be under irrigated conditions, and the other will be rainfed only.

Objective 3)

Based on the 1st year’s findings, lines with contrasting RSA will be further explored to identify QTLs or genomic loci using advanced genomic tools (GWAS) and additional field experiments to identify novel genes for optimizing the cotton RSA for enhanced water capture and efficiency.

Objective 4)

Working to understand the mechanisms by which the RSA and root water uptake function at deep soil layers and shallow zones. Investigate water movement from soil to roots in relation to cotton’s variation of traits.