Cotton yields often suffer due to drought, especially since most of the state’s cotton depends on rain rather than irrigation. The ability of cotton plants to adjust root growth based on moisture availability can substantially influence their productivity.
How root traits impact cotton yields
The research, led by Sruthi Narayanan, associate professor of crop ecophysiology at Clemson, demonstrated that adaptable root systems are crucial. Plants with flexible root traits adjust growth depending on soil moisture:
- In dry conditions, adaptable cotton varieties develop deeper roots, allowing them to access moisture stored deeper in the soil. This deep rooting helps plants utilize water more efficiently, increasing above-ground growth and overall yields.
- In wet conditions, these same varieties concentrate root growth closer to the soil surface. This shift conserves energy by preventing unnecessary deep root growth, reallocating energy to plant growth and yield development.
“These findings highlight the importance of selecting cultivars with adaptable root systems to enhance crop performance under varying environmental conditions,” said Om Prakash Ghimire, a doctoral student and lead author of an article about the study
Understanding the roots-to-shoots relationship
The study emphasized water use efficiency, a measure crucial for crop resilience under climate variability. It evaluates how much biomass or yield a crop produces per unit of water—essentially “crop per drop.”
Michael Jones, Clemson Extension cotton specialist and co-author, explained that higher shoot biomass typically leads to higher yields, although this relationship can plateau at a certain point. Biomass, encompassing stems, leaves, buds and flowers, is crucial because shoots direct carbon to the roots, receiving water and nutrients in return.
Fine roots vs. deep roots: What’s best?
The researchers clarified that optimal root traits depend on soil conditions:
- Fine roots efficiently capture water and nutrients, supporting overall growth and yield, especially in shallow soils or when resources are abundant.
- Deep roots provide stability and access to deeper water and nutrient reserves, which are essential during drought conditions.
“Fine roots absorb more water and nutrients and are beneficial in both shallow and deep soil, depending on nutrient and moisture availability,” Ghimire said. “Deep roots are crucial when water and nutrients are scarce in shallow soil, which often happens during droughts.”
Impact on South Carolina cotton growers
The research identified three cotton genotypes—Station Miller, Paymaster HS26 and PD 2164—with ideal root architecture, correlating to higher shoot biomass, water use efficiency and cotton yield.
“These genotypes can be used as germplasm sources for improved root traits and to study their genetic regulation,” Ghimire said.
Economic impact
Cotton, the world’s leading natural fiber, contributes significantly to South Carolina’s economy. Nationally, cotton generates over $120 billion annually, with the U.S. exporting approximately 30% of the global cotton trade.
Improving cotton yields through adaptable root traits not only benefits South Carolina farmers directly but also enhances economic sustainability for the broader agricultural industry as well.
Source : clemson.edu