Towards 3D Crop Phenotyping of Above- and Belowground Grain Sorghum Plant Traits Using Airborne Mounted Multispectral Camera, TLS, and GPR Remote Sensing Technologies

Remote sensing technologies are increasingly being used in agriculture with a focus on crop phenotyping and nondestructive plant health monitoring. Climate change in the western United States has led to increasing aridity, and reduced precipitation and thus a growing need for emerging varieties of drought-tolerant crops and technology to accurately monitor their establishment. Remote sensing technologies have the capability of efficiently fulfilling this need. The utilization of terrestrial laser scanning (TLS), ground penetrating radar (GPR) and small unoccupied aerial vehicles (sUAS) allow us to monitor and assess plant traits and health metrics. These three technologies were employed during the 2021 and 2022 growing seasons of two varieties of droughttolerant grain sorghum (Sorghum Bicolor L. Moench) under deficit irrigation. The red and white varieties of sorghum were monitored using a randomized split plot design with three levels of deficit irrigation (30%, 60%, and 100%). These plots were replicated three times for a total of 18 plots. We hypothesized that crop height and an index of plant health: the normalized difference vegetation index (NDVI), would significantly decrease and that the sorghum's belowground biomass (BGB) would increase, as an indication of drought tolerance, in response to deficit irrigation. For both the 2021 and 2022 growing seasons, we measured changes in plant height, NDVI, and below-ground root response using a Leica C10 TLS, a MicaSense Altum multispectral camera mounted on a DJI Matrice 600 Pro sUAS, and an IDS GeoRadar RIS MF Hi-Mod dual frequency (400/900 MHz) GPR, respectively. Our hypotheses of a decrease in above-ground plant traits, i.e., height for both varieties in response to deficit irrigation treatments were confirmed. However, for NDVI, the red variety increased with decreasing water availability, and the white variety was consistent with our hypothesis. We found significant differences in the amplitude response maps, a surrogate of BGB phenology, that indicated increasing biomass with increasing deficit irrigation. However, this response was not consistent with field measures of BGB that showed the highest BGB at 60%, then 100%, and then 30%. This indicated that a 30% deficit level exceeded drought tolerance for the two varieties. These results support the use of remote sensing technologies for field plot-level plant health monitoring and crop phenotyping.

Level thesis:degree_level

Master's Degree

Year dc:date.issued

2023

Author dc:creator

• Godkin, Russell Stuart

Advisor dc:contributor.advisor

• Washington-Allen, Robert

Committee members dc:contributor.committeemember

• Yerka, Melinda K
• Louie, John N

• Agriculture
• Remote Sensing

Handle dc:identifier.uri

http://hdl.handle.net/11714/8571

OAI identifier oai:identifier

oai:scholarwolf.unr.edu:11714/8571