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CHAMPAIGN, IL – Scientists report that it is possible to detect and predict heat damage in crops by measuring the fluorescent light signature of plant leaves exposed to heat stress. If this fluorescent signal is collected via satellite, it could aid comprehensive monitoring of growth and crop yield under the heat stress of climate change, the researchers say.
Their study measures sun-induced chlorophyll fluorescence (SIF) to monitor a plant’s photosynthetic health and to establish a link between heat stress and crop yield. The results are published in the journal Global Change Biology.
Sun-induced chlorophyll fluorescence occurs when some of the photosynthetic energy is emitted in the form of near-infrared light from plant leaves, the researchers said.
“There is a connection between sun-induced chlorophyll fluorescence and the rate of photosynthesis in plants. However, it was unclear whether the SIF detection could measure physiological responses in heat-stressed plants, ”said lead author Hyungsuk Kimm, a graduate student in natural, resource and environmental sciences at Urbana-Champaign, University of Illinois. “For example, when soybeans are exposed to high temperature stress, they do not show any significant changes in the canopy structure, and conventional remote sensing signals do not provide unambiguous spectral sequential signatures.”
To clarify the relationship between SIF and crop yield, the researchers used a hyperspectral sensor system to measure SIF over soybean crops in the U. of I. trial plots in central Illinois. The setup monitored changes in chlorophyll fluorescence from soybean leaf canopies in a controlled environment using infrared lamps to raise temperatures 1.5, 3.0, 4.5 and 6.0 degrees Celsius above the ambient temperature of the crop roofs, reports the study.
Figure shows (a) the experimental setup and photos of the field measurement (b) a researcher using a spectroscopy system and (c) the canopy chamber system.
Courtesy Hyungsuk Kimm
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“This experimental setup – and it’s a large temperature gradient – is the first of its kind,” said co-author Carl Bernacchi, professor of plant biology and plant science and research scientist with the US Department of Agriculture’s Agricultural Research Service at the U. von I.
“We found that sun-induced fluorescence reacts to increases in temperature and corresponds to soybean leaves of increasingly poor quality,” said Kaiyu Guan, professor of natural and resource and environmental sciences who led the study. “We also found that heat stress has a huge impact on soybeans during their reproductive phase when the plants are producing grain, which ultimately affects the size and quantity of the resulting soybeans.”
This study establishes a correlation between heat stress, SIF and grain quality and shows how heat stress affects photosynthesis performance and crop yield.
“The technique can provide a tool for growers to identify more heat-resistant crops and help farmers choose the best crops to grow in the US corn belt when temperatures rise, as many climate models predict,” said co-author Lisa Ainsworth, a professor of plant biology and a scientist at the US Department of Agriculture in Illinois.
Illinois researchers Charles Burroughs, Bin Peng, Caitlin Moore, and Genghung Wu also participated in this research. The US Department of Agriculture, NASA, and the National Science Foundation supported this study.
Guan is also a member of the National Center for Supercomputing Applications and the Institute for Sustainability, Energy and Environment. Bernacchi and Ainsworth are also affiliated with the Carl R. Woese Institute for Genome Biology. Guan, Ainsworth, and Bernacchi found faculty members at the Agroecosystem Sustainability Center in Illinois.