Estimating canopy-level photosynthetic capacity using reflectance
spectra and solar-induced fluorescence
Abstract
Improving photosynthesis has been considered critical to increasing crop
yield to meet food demands from a growing population. To achieve this
goal, high-throughput phenotyping techniques are highly needed to
explore both natural and genetic variation in photosynthetic performance
among crop cultivars. Due to the non-invasive nature of hyperspectral
imaging, there is an increasing use of hyperspectral imaging for
phenotyping of photosynthesis or photosynthetic physiology. The use of
hyperspectral sensors has resulted in the accumulation of large amounts
of data, shifting the research efforts into efficiently mining spectral
information for high-throughput phenotyping. In this presentation, we
will introduce data pipelines developed to leverage proximal sensing
platforms and data sources including both reflectance spectra and
solar-induced fluorescence (SIF) for quantifying photosynthetic
performance at the canopy level. Photosynthetic performance was
represented by the maximum carboxylation rate (Vcmax) and the maximum
electron transport rate (Jmax). The experiments were conducted using
eleven tobacco cultivars grown in field conditions during 2017 and 2018
at Energy Farm at University of Illinois. Time-synchronized
hyperspectral images from 400 to 900 nm and irradiance measurements of
sunlight under clear-sky conditions were collected for capturing
reflectance spectra and SIF (and SIF related parameters). Within 30
minutes of spectral measurements, ground-truth Vcmax and Jmax were
obtained from portable leaf gas exchange system. Our results suggested
both reflectance spectra and SIF can provide accurate estimations of
Vcmax and Jmax. The presented data pipelines have potential to relieve
bottleneck in phenotyping of photosynthesis for breeding cultivars of
enhanced photosynthesis.