UV-B radiation affects agriculture in complex interactions with climate change. Increasing UV-B radiation is known to harm crops, causing damage in 2/3 of over 680 plant cultivars tested. UV-B radiation can harm crops directly, through heritable mutations in DNA, changes to membranes, protein denaturation, and indirectly through changes to several physiological and growth processes. UV-B radiation affects species and even plant cultivars differently, and little is known how changing UV-B radiation affects crops, in order to develop algorithms for models for crops. Also not well understood is how UV-B radiation affect crops in combination with other environmental stressors. UV-B radiation can affect crops in complex ways, harming well-watered plants more than plants under drought for some crop species, while harming plants fertilized in excess more than those adequately fertilized, but these effects have been studied only in a few species. UV-B radiation as well as visible light accelerate litter decomposition in a process called photodegradation, possibly stimulating more nutrients to be released from the litter and then taken up by plants to produce more biomass or improve nutrition in rangelands of the western U.S. that receive high doses of solar radiation.
UVMRP studies both isolated and combined effects of UV-B radiation with environmental stressors. The studies are on crops, trees and rangeland, and consider the effects of UV-B radiation alone and combined with other environmental stressors such as moisture (drought), temperature, ozone, soil nutrients and CO2. The results of the studies will be incorporated into models of crops, trees and rangelands.
These studies are continuing at Mississippi State University (MSU) and Colorado State University. Primary studies use plant growth chambers known as the Soil-Plant-Atmosphere-Research (SPAR) facility at MSU, which is capable of controlling the aerial environment over a wide range of set points (atmospheric CO2 concentration, humidity, and UV-B radiation). The primary studies are complemented by other lab and field experiments, satellite observations, and modeling.
For more detail about current and past research, select an interest below.
Cotton
The studies on cotton aim to understand the interactive effects of UV-B radiation and environmental stressors on cotton growth, development, and yield. Using the SPAR facility at MSU, the objectives of these studies were to test the hypothesis that elevated UV-B radiation will modify transpiration, respiration, carbon acquisition, development, reproduction and yield, and to understand the physiological, anatomical and phenological basis of these effects. The studies developed algorithms describing the effects of UV-B radiation, and we incorporated the algorithms into a physiological crop model, GOSSYM, and tested with an impact analysis in the fourteen Southern states.
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Liang, X., M. Xu, W. Gao, K. R. Reddy, K. Kunkel, D. L. Schmoldt, and A. N. Samel. 2012. A Distributed Cotton Growth Model Developed from GOSSYM and Its Parameter Determination. Agronomy Journal, 104(3), 661-674. doi: 10.2134/agronj2011.0250
Liang, X., M. Xu, W. Gao, K. R. Reddy, K. Kunkel, D. L. Schmoldt, and A. N. Samel. 2012. Physical Modeling of U.S. Cotton Yields and Climate Stresses during 1979 to 2005. Agronomy Journal, 104(3), 675-683. doi: 10.2134/agronj2011.0251
Wang, X., W. Gao, J. R. Slusser, J. Davis, B. Olson, S. Janssen, G. Janson, B. Durham, R. Tree, and R. Deike. 2006. USDA UV-B monitoring system: An application of centralized architecture. Computers and Electronics in Agriculture, 64(2), 326-332. doi: 10.1016/j.compag.2008.04.006
Zhao, D., K. R. Reddy, V. G. Kakani, S. Koti, and W. Gao. 2005. Physiological causes of cotton fruit abscission under conditions of high temperature and enhanced ultraviolet-B radiation. Physiologia Plantarum, 124(2), 189-199. doi: 10.1111/j.1399-3054.2005.00491.x
Reddy, K. R., S. Koti, V. G. Kakani, D. Zhao, and W. Gao. 2005. Genotypic variation of soybean and cotton crops in their response to UV-B radiation for vegetative growth and physiology. Proceedings of SPIE, Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, 5886, 58860K. doi: 10.1117/12.619899
Kakani, V. G., K. R. Reddy, D. Zhao, and W. Gao. 2004. Senescence and hyperspectral reflectance of cotton leaves exposed to ultraviolet-B radiation and carbon dioxide. Physologia Plantarum, 121(2), 250-257. doi: 10.1111/j.1399-3054.2004.00314.x
Reddy, K. R., V. G. Kakani, D. Zhao, S. Koti, and W. Gao. 2004. Interactive Effects of Ultraviolet-B Radiation and Temperature on Cotton Physiology, Growth, Development and Hyperspectral Reflectance. Photochemistry and Photobiology, 79(5), 416-427. doi: 10.1111/j.1751-1097.2004.tb00029.x
Zhao, D., K. R. Reddy, V. G. Kakani, A. R. Mohammed, J. J. Read, and W. Gao. 2004. Leaf and canopy photosynthetic characteristics of cotton (Gossypium hirsutum) under elevated CO2 concentration and UV-B radiation. Journal of Plant Physiology, 161(5), 581-590. doi: 10.1078/0176-1617-01229
Kakani, V. G., K. R. Reddy, D. Zhao, and W. Gao. 2004. Leaf senescence and hyperspectral reflectance of cotton leaves exposed to ultraviolet-B radiation and carbon dioxide. Physologia Plantarum, 121(2), 250-257.
Gao, W., Y. Zheng, J. R. Slusser and G. M. Heisler. 2003. Impact of enhanced Ultraviolet-B irradiance on cotton growth, development, yield, and qualities under field conditions. Agricultural and Forest Meteorology, 120(1-4), 241-248.
Reddy, K. R., V. G. Kakani, D. Zhao, A. R. Mohammed, and W. Gao. 2003. Cotton responses to Ultraviolet-B radiation: experimentation and algorithm development. Agricultural and Forest Meteorology, 120, 249-266.
Corn
The ongoing studies on corn use the SPAR facility to grow the corn cultivars at a wide range of UV-B levels, and track growth, morphology, and photosynthetic rates. The preliminary results of the studies show that corn, grown under optimal nutrient, water, and temperature, is affected even at ambient levels of UV-B. Some corn cultivars are more sensitive to UV-B than others. The results are currently being used to develop an UV-B dose response curve for corn growth that can be converted into functional algorithms for better modeling corn growth similarly to those developed for cotton. The studies followed a previous study that tested the effects of UV-B radiation in the field. The results of the field study show that UV-B radiation reduces corn growth in the field.
Wijewardana, C., W. Brien Henry, W. Gao, and K. Raja Reddy. 2016. Interactive effects on CO2, drought, and ultraviolet-B radiation on maize growth and development. Journal of Photochemistry and Photobiology, B: Biology 160 198–209. doi: 10.1016/j.jphotobiol.2016.04.004
Singh, S. K., K. R. Reddy, V. R. Reddy, and W. Gao. 2014. Maize growth and developmental responses to temperature and ultraviolet-B radiation interaction. Photosynthetica, 52(2), 262-271. doi: 10.1007/s11099-014-0029-6
Reddy, K. R., S. K. Singh, S. Koti, V. G. Kakani, D. Zhao, W. Gao, and V. R. Redd. 2013. Quantifying the Effects of Corn Growth and Physiological Responses to Ultraviolet-B Radiation for Modeling. Agronomy Journal, 105(5), 1367-1377. doi: 10.2134/agronj2013.0113
Gao, W., Y. Zheng, J. R. Slusser, G. M. Heisler, R. H. Grant, J. Xu, and D. He. 2004. Effects of supplementary ultraviolet-B irradiance on maize yield and qualities: a field experiment. Photochemistry and Photobiology, 80(1), 127-131. doi: 10.1111/j.1751-1097.2004.tb00060.x
Grapes
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The studies on grapes focused on the effects of UV-B radiation on grape disease, grapevine powdery mildew. Done by collaborators at Cornell University, the studies showed that ambient levels of UV-B radiation inhibit mildew germination and establishment, and prevent the development of mildew colonies. The studies demonstrated that the grape growers can limit the mildew by increasing sunlight intercepted by leaves and fruits.
Austin, C. N. and Wilcox, W. F. 2012. Effects of sunlight exposure on grapevine powdery mildew development. Phytopathology102:857-866.
Austin, C.N., Meyers, J., Grove, G.G., and Wilcox, W.F. 2011. Quantification of powdery mildew severity as a function of canopy variability and associated impacts on sunlight penetration and spray coverage within the fruit zone. Amer. J. Enol. Vitic. 62 (1):23-31.
Rangeland
The rangeland study examined the influence of UV-B radiation on plant production, litter decomposition and soil carbon storage in the shortgrass steppe, an important rangeland of western US. With collaborators at Colorado State University, the studies found that some plant species grew more when UV-B radiation was blocked but only in dry years, while other species did so only on wet years. Some species also produced foliage of better quality for grazing with ambient levels of UV-B radiation, but this depended on precipitation.
Milchunas, D. G., J. Y. King, A. R. Mosier, J. C. Moore, J. A. Morgan, M. H. Quirk, and J. R. Slusser. 2004. UV radiation effects on plant growth and forage quality in a shortgrass steppe ecosystems. Photochemistry and Photobiology, 79(5), 404-410. doi: 10.1111/j.1751-1097.2004.tb00027.x
King, J. Y., D. G. Milchunas, A. R. Mosier, J. C. Moore, M. H. Quirk, J. A. Morgan, and J. R. Slusser. 2003. Initial impacts of altered UVB radiation on plant growth and decomposition in shortgrass steppe. Proceedings of SPIE, Ultraviolet Ground- and Space-based Measurements, Models, and Effects III, 5156, 384-395. doi: 10.1117/12.508606
Canopy
The studies on canopy aimed to develop a 3D canopy model that can predict the amount of UV-B within and under a vegetation canopy. The studies resulted in a 3-D UV Radiation Transfer model, which calculates the amount of UV-B radiation passing through a canopy at any location below a canopy. Given sky conditions and canopy composition and structure, this model can predict UV-B levels below canopies of agricultural crops, orchards, and trees in urban areas.
Beneski, E., J. H. Bassman, J. R. Slusser, and W. Gao. 2005. Application of CCD array digital fiber optic spectrometers in determination of within-tree and within- canopy irradiances of UV-B radiation. Proceedings of SPIE, Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, 5886, 58860X. doi: 10.1117/12.620659
Gao, W., R. H. Grant, G. M. Heisler and J. R.Slusser. 2003. Ultraviolet-B radiation in a row-crop canopy: An extended 1-D model. Agricultural and Forest Meteorology, 120(1-4), 141-151.
Heisler, G. M., R. H. Grant, D. J. Nowak, W. Gao, D. E. Crane, and J. T. Walton. 2003. Inclusion of an Ultraviolet Radiation transfer component in an urban forest effects model for prediction tree influences in potential below- canopy exposure to UVB radiation. Proceedings of SPIE, Ultraviolet Ground- and Space-based Measurements, Models, and Effects III, 5156, 228-235. doi: 10.1117/12.509193
Gao, W., R. H. Grant, G. M. Heisler, and J. R. Slusser. 2001. Modeling ultraviolet-B radiation in a maize canopy. Proceedings of SPIE, Ultraviolet Ground- and Space-based Measurements, Models, and Effects, 4482, 395-407. doi: 10.1117/12.452943
Trees
The studies on trees examine how tree leaves absorb, reflect, and pass UV-B radiation. With collaborators from Southern University, the USDA Forest Service Northeastern Research Station, and the University of Vermont, the studies examined how tree leaves tolerate UV-B radiation, for more than 30 common broadleaf tree species in the southern US. The studies established a database of leaf optical properties, depth of UV-B penetration into leaves, concentration of UV-B absorbing compounds, and leaf anatomy. The studies showed that on a whole leaf basis, the tree leaves absorb 91% −95%, reflect 5% − 9%, and transmit less than 1% incident UV-B radiation. They also showed that leaf chlorophyll content predicted the green light reflectance, transmittance, and absorbance, and that UV-B reflectance was predicted by leaf thickness and leaf UV-B absorbing compound concentrations.
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Chapter: Characteristics of UV-B Radiation Tolerance in Broadleaf Trees in Southern USA, UV Radiation in Global Climate Change. Yadong Qi, Gordon M. Heisler, Wei Gao, Thomas C. Vogelmann, Shuju Bai
Thines, N. J., L. A. Shipley, J. H. Bassman, J. K. Fellman, D. S. Mattison, J. R. Slusser, and W. Gao. 2007. Effects of Enhanced UV-B Radiation on Plant Chemistry: Nutritional Consequences for a Specialist and Generalist Lagomorph. Journal of Chemical Ecology, 33(5), 1025-1039. doi: 10.1007/s10886-007-9280-7
Yadong Qi, Shuju Bai, Gordon M. Heisler. 2003. Changes in ultraviolet-B and visible optical properties and absorbing pigment concentrations in pecan leaves during a growing season. Agriculture and Forest Meteorology 12/2003. doi: 10.1016/j.agrformet.2003.08.018