Assessing the response of Tropical Japonica accessions under alternate-wetting-drying conditions through hyperspectral analysis

Authors: Sells, Laduska; Huggins, Trevis; Edwards, Jeremy; Rice, Adam; Moser, Jonathan

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/13/2024
Publication Date: 1/5/2026
Citation: Sells, L.J., Huggins, T.D., Edwards, J., Rice, A.D., Moser, J.G. 2026. Assessing the response of Tropical Japonica accessions under alternate-wetting-drying conditions through hyperspectral analysis. Rice Technical Working Group Meeting Proceedings. New Orleans, Louisiana. February 17-20, 2025.

Interpretive Summary:

Technical Abstract: Spectra-radiometry captures the interaction of spectral wavelengths and matter in the form of wavelengths and amplitudes. The reflectance of different wavelengths of light by the plant canopy, a key indicator of plant health, is influenced by its’ optical properties to produce a unique signature. The reflected spectra of plant canopies provide information that can be used to assess a range of parameters, including green biomass, photosynthetic size, water status and environmental stresses. Spectral reflectance can be measured with hyperspectral cameras or spectroradiometers which have a typical spectral range of 350-1100 nm. The understanding of optical properties of plant canopies has facilitated the development of a series of assays known as spectral reflectance indices (SRI). These SRI include the normalized difference vegetation index (NDVI), which measures green biomass of canopy; photochemical reflectance index (PRI), which estimates solar radiation use efficiency; water index (WI) and normal water index 1 (NWI-1), which both estimate the water status of the canopy. Alternate-wetting drying (AWD) was applied to a field of 134 tropical japonica accessions. AWD is a management technique in rice used to reduce irrigation by allowing fields to naturally dry down and not remain under constant flood. In this study, the spectra of 134 tropical japonica accessions were collected under AWD conditions to screen for individuals with traits that can be beneficial for production under reduced irrigation. The spectral data showed variation in the reflectance spectra of the accessions across two dry downs. Specific wavelengths were extracted from the spectra and used to estimate several SRIs including NDVI, PRI, WI and NWI-1. The response of the accessions to AWD compared to the flood treatment was significant different for NDVI, PRI, WI and NWI-1. The data also indicated that the accessions under AWD had varied responses according to NDVI, PRI, WI and NWI-1. Several accessions, Mato Grosso, Quinimpol, Leah, and IITA 130, were some of the accessions that were less affected by the AWD treatments according to NDVI, PRI, WI and NWI-1. These accessions were some of several with green canopies at the second dry down cycle. The SRI show potential to be reliable tools to select materials for tolerance to stress from production under reduced irrigation conditions.