Rapid Estimation of Straw Residue Decomposition in Winter Wheat

View the project final report

Commodities

• Agronomic: wheat

Practices

• Crop Production: conservation tillage, no-till
• Soil Management: soil quality/health

Less tillage is needed in winter wheat cropping systems in the Pacific Northwest to alleviate soil
erosion by both winter and water. Wheat straw residue decomposition rate is one way to
accomplish this. Slow decomposition in the low yielding winter wheat/summer fallow areas will
leave more residue on the soil surface longer, helping prevent wind erosion. Fast decomposition
in the high yielding annual cropping areas will limit the need for tillage to help break down
residue quickly, thereby helping prevent soil erosion by water. This research aims to 1)
understand the genetic regions controlling rapid residue decomposition, 2) identify a rapid
method to estimate straw decomposition rate through near-infrared spectroscopy (NIRS), and 3)
estimate decomposition rates of currently available winter wheat cultivars. A panel of 480
diverse winter wheat lines grown over two years at five locations will be used to perform a
genome-wide association study to identify genetic regions controlling residue decomposition.
These lines will be analyzed for lignin, cellulose, and hemicellulose components, as well as C
and N ratios. Furthermore, the same straw will be subjected to NIRS, and data will be used to
develop models to rapidly predict residue decomposition. Finally, released cultivars in the PNW
will be analyzed to estimate their residue decomposition rates, and information will be provided
to growers. This information will allow growers to select cultivars specific to their cropping
system, thereby reducing tillage requirements. Reduced tillage will prevent both wind and water
soil erosion. The long-term goal of this project is to provide growers with cultivars which are
specifically adapted to no-till cropping systems, thereby reducing some of the risk associated
with the transition from conventional to no-till systems.

1. Phenotype a panel of 480 winter wheat varieties for NDF, ADF, and ADL and C, N, and
C:N ratio.
2. Use NIRS and ISIscan software to obtain predictions models for NDF, ADF, ADL, C, N,
and C:N in winter wheat.
3. Obtain straw decomposition estimations through the described methods from the varieties
displayed in the 2018 WSU Extension Cereal Variety Testing Program.
4. Use the data collected for the decomposition constituents and perform a GWAS to draw
associations between those traits and known molecular markers.
5. Create and distribute bulletins containing information about various winter wheat
cultivars, including the decomposition rates.