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

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Commodities

• Agronomic: cotton

Practices

• Crop Production: plant breeding and genetics, water management

Southwest Texas has been experiencing years of drought that is expected to continue. Cotton is the major crop of West Texas that requires less water comparatively, but extreme conditions affect its growth, yield, and development. Water saving technologies are needed to improve water efficiency in crops. A major bottleneck in water-saving technologies that cotton faces is the lack of mechanistic understanding of diversity in root systems for further genetic improvement. It is well-studied that genetic differences in root system architecture (RSA) and associated traits such as root biomass, depth, and overall morphology, can positively overcome the water deficit conditions in crops. Studies have shown that genetic differences in root system architecture can positively overcome water-deficit conditions in different crops. However, the adaptation of root systems to a semi-arid environment and underlying genetic mechanisms is not well studied in many crops, especially cotton. Cotton possesses a deep taproot but lacks active shallow roots which can be a sustainable strategy in the West Texas region. When limited rainwater is available for a short period of time, it cannot reach the deep root zones. Active shallow roots could improve water and nutrient uptake near the surface and sub-surface regions. Considering the advantages of root systems and underlying genetics, our project will investigate the root phenotypic plasticity of diverse landraces, commercial cultivars and lines grown in West Texas. A comprehensive evaluation will lay a foundation to optimize the root system architecture and offer sustainable solutions to improve water efficiencies under water-deficit conditions.  

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.   

2) a) Evaluate the root system architecture (RSA) of the diverse germplasm using 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 5 most promising and the 5 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-deficit treatments in field conditions, three replications will be under irrigated conditions and the other will be rainfed only. 

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. 

4) Working in collaboration with soil physicist (Dr. Deb) to understand the mechanisms by which the RSA and root water uptake functions at deep soil layers and shallow zones. Investigate the water movement from soil to roots in relation to cotton’s variation of traits.