Progress 09/15/01 to 03/31/04
Outputs
Increases in the Earths surface UV-B radiation and atmospheric CO2 concentration [CO2] are two major concerns in climate change arena. Although numerous studies have been conducted on either enhanced UV-B or elevated [CO2] effects on crop growth, development, and yield, little is known about the interactive effects of the two factors on growth and physiology of cotton, an important economic crop worldwide. The objective of this study was thus to determine the interactive effects of elevated [CO2] and UV-B radiation on cotton growth and physiology under controlled environment conditions. Information related to whole plant and leaf-level processes will contribute to filling gaps in our knowledge base and understanding. An experiment was conducted in sunlit, controlled environment chambers known as Soil-Plant-Atmosphere-Research units to determine the interactive effects of atmospheric [CO2] and UV-B radiation on cotton growth, development and leaf photosynthetic
characteristics. Six treatments were comprised of three levels of biologically effective UV-B radiations [0 (control), 7.7, and 15.1 kJ m-2 d-1] and two levels of [CO2] (360 and 720 mol mol-1). Treatments were imposed for 66 days from emergence through three weeks after the first flower stage. Plants grown in elevated [CO2] had greater leaf area and higher leaf photosynthesis (Pn), nonstructural carbohydrates, and total biomass than plants grown in ambient [CO2]. The results indicated that there was some CO2 UV-B interactive effects on cotton leaf Pn, phenolics, wax, nonstructural carbohydrate concentrations and other physiological parameters measured. Near current solar UV-B radiation (8 kJ m-2 d-1) normally observed in US Midsouth cotton production area on sunny days between May and August did not affect cotton leaf Pn and total biomass production, but significantly increased fruit abscission and decreased fruit dry matter accumulation compared to plants that received no UV-B
radiation. A doubling of the current UV-B radiation to 16 kJ m-2 d-1 further reduced fruit production and total biomass. Decreased biomass from high UV-B radiation was closely related to both smaller leaf area and lower leaf Pn. Elevated [CO2] significantly increased Pn, growth and dry matter accumulation in cotton under no UV-B or 7.7 kJ m-2 d-1 UV-B conditions. However, elevated atmospheric [CO2] did not alleviate the detrimental effects of high UV-B radiation on cotton Pn and growth, particularly on reproductive growth. Decreased number of fruits in cotton exposed to UV-B radiation suggests that breeding UV-B radiation-tolerant cultivars is important even under ambient [CO2] and UV-B levels, and that tolerance to UV-B radiation will be even more important in future higher [CO2] and solar UV-B radiation environments. The data collected will aid in our understanding of cotton responses to enhanced UV-B radiation and aid in the development of process-level crop models that can be used
in impact analysis and assessment to assist science-based policy decisions.
Impacts
Understanding crop responses to Ultraviolet-B radiation is providing 1) the quantitative algorithms that can be incorporated into crop models which can be used to study the impacts of UV-B radiation on cotton yields across the U.S. Cotton Belt and 2) the traits that can be used in plant breeding programs to screen and develop UV-B tolerant cotton genotypes.
Publications
- Razack, M. A., Reddy, K. R., Zhao, D. and Kakani, V. G. 2002. Cotton photosynthestic responses to ultraviolet-B radiation and elevated CO2. Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Reddy, K. R., Mohammed, A. R. Zhao, D., Kakani, V. G. and Brand, D. 2002. Brand Influence of Ultraviolet-B Radiation and Atmospheric CO2 on Leaf Morphology. Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Kakani, V. G., Reddy, K. R., Zhao, D. and Read, J. J. 2002. Influence of Ultraviolet (UV-B) radiation and elevated CO2 on leaf reflectance properties of cotton (Gossypium hirsutum). Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Zhao, D., Reddy, K. R. and Kakani, V. G. 2002. Effects of UV-B radiation and elevated CO2 on growth and development of cotton plant . Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Kakani, V. G., Reddy, K. R., Zhao, D., Mohammed, A. R. and Gao, W. 2002. Quantifying the effects of ultraviolet-B radiation on cotton growth and development. 32nd Biological Systems Simulation Work Group Symposium/Workshop on Remote Sensing and Modeling Applications for Natural Resource Management, 10-13 March 2002, Mississippi State, MS, USA. Vol. 32: p. 26.
- Reddy, K. R. 2002. The Soil-Plant-Atmosphere-Research (SPAR) facility A tool for plant science research and modeling. 32nd Biological Systems Simulation Work Group Symposium/Workshop on Remote Sensing and Modeling Applications for Natural Resource Management, 10-13 March 2002, Mississippi State, MS, USA.Vol. 32: p. 43.
- Reddy, K. R, Kakani, V. G., Zhao, D. and Gao, W. 2002. Cotton responses to UV-B radiation: experimentation and modeling. The SPIE's Third International Asia-Pacific Symposium on Remote Sensing of the Atmosphere, Ocean, Environment, and Space, 23 to 27 October 2002, China.
- Kakani, V. G., Reddy, K. R., Zhao, D. and Carter, G. A.. 2002. Changes in hyperspectral reflectance of cotton leaves exposed to enhanced ultraviolet-B radiation. American Society Annual Meetings, November 10-14, 2002, Indianapolis, IN.
- Reddy, K. R., Kakani, V. G. and Zhao, D. 2002. Changes in hyperspectral reflectance of aging and senescing cotton leaves exposed to enhanced ultraviolet-B radiation and carbon dioxide. American Society Annual Meetings, November 10-14, 2002, Indianapolis, IN.
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Progress 01/01/02 to 12/31/02
Outputs
Increases in the Earth's surface UV-B radiation and atmospheric CO2 concentration [CO2] are two major concerns in climate change arena. Although numerous studies have been conducted on either enhanced UV-B or elevated [CO2] effects on crop growth, development, and yield, little is known about the interactive effects of the two factors on growth and physiology of cotton, an important economic crop worldwide. The objective of this study was thus to determine the interactive effects of elevated [CO2] and UV-B radiation on cotton growth and physiology under controlled environment conditions. Information related to whole plant and leaf-level processes will contribute to filling gaps in our knowledge base and understanding. An experiment was conducted in sunlit, controlled environment chambers known as Soil-Plant-Atmosphere-Research units to determine the interactive effects of atmospheric [CO2] and UV-B radiation on cotton growth, development and leaf photosynthetic
characteristics. Six treatments were comprised of three levels of biologically effective UV-B radiations [0 (control), 7.7, and 15.1 kJ m-2 d-1] and two levels of [CO2] (360 and 720 mol mol-1). Treatments were imposed for 66 days from emergence through three weeks after the first flower stage. Plants grown in elevated [CO2] had greater leaf area and higher leaf photosynthesis (Pn), nonstructural carbohydrates, and total biomass than plants grown in ambient [CO2]. The results indicated that there was some CO2 UV-B interactive effects on cotton leaf Pn, phenolics, wax, nonstructural carbohydrate concentrations and other physiological parameters measured. Near current solar UV-B radiation (8 kJ m-2 d-1) normally observed in US Midsouth cotton production area on sunny days between May and August did not affect cotton leaf Pn and total biomass production, but significantly increased fruit abscission and decreased fruit dry matter accumulation compared to plants that received no UV-B
radiation. A doubling of the current UV-B radiation to 16 kJ m-2 d-1 further reduced fruit production and total biomass. Decreased biomass from high UV-B radiation was closely related to both smaller leaf area and lower leaf Pn. Elevated [CO2] significantly increased Pn, growth and dry matter accumulation in cotton under no UV-B or 7.7 kJ m-2 d-1 UV-B conditions. However, elevated atmospheric [CO2] did not alleviate the detrimental effects of high UV-B radiation on cotton Pn and growth, particularly on reproductive growth. Decreased number of fruits in cotton exposed to UV-B radiation suggests that breeding UV-B radiation-tolerant cultivars is important even under ambient [CO2] and UV-B levels, and that tolerance to UV-B radiation will be even more important in future higher [CO2] and solar UV-B radiation environments. The data collected will aid in our understanding of cotton responses to enhanced UV-B radiation and aid in the development of process-level crop models that can be used
in impact analysis and assessment to assist science-based policy decisions.
Impacts
Understanding crop responses to Ultraviolet-B radiation is providing 1) the quantitative algorithms that can be incorporated into crop models which can be used to study the impacts of UV-B radiation on cotton yields across the U.S. Cotton Belt and 2) the traits that can be used in plant breeding programs to screen and develop UV-B tolerant cotton genotypes.
Publications
- Kakani, V. G., Reddy, K. R., Zhao, D. and Read, J. J. 2002. Influence of Ultraviolet (UV-B) radiation and elevated CO2 on leaf reflectance properties of cotton (Gossypium hirsutum). Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Zhao, D., Reddy, K. R. and Kakani, V. G. 2002. Effects of UV-B radiation and elevated CO2 on growth and development of cotton plant. Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Reddy, K. R. 2002. The Soil-Plant-Atmosphere-Research (SPAR) facility - A tool for plant science research and modeling. 32nd Biological Systems Simulation Work Group Symposium/Workshop on Remote Sensing and Modeling Applications for Natural Resource Management, 10-13 March 2002, Mississippi State, MS, USA.Vol. 32: p. 43.
- Reddy, K. R, Kakani, V. G., Zhao, D. and Gao, W. 2002. Cotton responses to UV-B radiation: experimentation and modeling. The SPIE's Third International Asia-Pacific Symposium on Remote Sensing of the Atmosphere, Ocean, Environment, and Space, 23 - 27 October 2002, China.
- Kakani, V. G., Reddy, K. R., Zhao, D. and Carter, G. A.. 2002. Changes in hyperspectral reflectance of cotton leaves exposed to enhanced ultraviolet-B radiation. American Society Annual Meetings, November 10-14, 2002, Indianapolis, IN.
- Reddy, K. R., Kakani, V. G. and Zhao, D. 2002. Changes in hyperspectral reflectance of aging and senescing cotton leaves exposed to enhanced ultraviolet-B radiation and carbon dioxide. American Society Annual Meetings, November 10-14, 2002, Indianapolis, IN.
- Razack, M. A., Reddy, K. R., Zhao, D. and Kakani, V. G. 2002. Cotton photosynthestic responses to ultraviolet-B radiation and elevated CO2. Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
- Reddy, K. R., Mohammed, A. R. Zhao, D., Kakani, V. G. and Brand, D. 2002. Brand Influence of Ultraviolet-B Radiation and Atmospheric CO2 on Leaf Morphology. Beltwide Cotton Conference, 8-12 January 2002, Atlanta, GA.
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Progress 01/01/01 to 12/31/01
Outputs
Two experiments were conducted to study the influence of enhanced UV-B radiation on cotton growth and development. Cotton plants were exposed to UV-B radiation treatments of 0, 4, 8, 12 and 16 kJ m-2 d-1 in experiment I and 0, 8, 16 kJ m-2 d-1 in experiment II from emergence to harvest (50 and 66 days after emergence, respectively), in a square wave approach for 8 h from 0800 to 1600 h. A UV-B index, described as ratio of treatment to control of a given growth or developmental parameter was used to describe the effects of UV-B radiation. The UV-B radiation had no effect on major cotton reproductive developmental parameters such as first fruiting branch position on main stem, and duration to squaring and flowering. Similarly, UV-B radiation did not affect the vegetative developmental aspects such as leaf initiation rates and duration of leaf expansion. Reduction in dry weight of leaf, stem, squares, bolls and root was recorded due to enhanced UV-B radiation in this
study. Biomass partitioning was altered by the UV-B radiation treatments with more of the total dry weight being partitioned to leaves and roots and less to squares and bolls at 8 and 16 kJ m-2 d-1 of UV-B radiation. Ability of cotton plants to retain bolls was the most sensitive growth parameter to enhanced UV-B radiation. Canopy photosynthesis was reduced due to the enhanced UV-B radiation treatments. The UV-B specific indices for growth and developmental parameters can be incorporated into cotton simulation models such as GOSSYM to predict cotton yields both in the present and in future climates with increased levels of UV-B radiation.
Impacts
This project was undertaken to addresses our long-term goal of understanding the interactive effects of environmental factors including UV-B radiation on cotton growth, development and yield. Our objectives are to test the hypothesis that elevated UV-B radiation will modify the response of transpiration, respiration, carbon acquisition, development, reproduction and yield of cotton and to understand the physiological, anatomical and phenological basis of these effects using an internationally unique system of daylight chambers known as Soil-Plant-Atmosphere-Research (SPAR) facility.
Publications
- Kakani, V. G., K.R. Reddy, D. Zhao, A.R. Mohammed and Wei Gao. 2002. Quantifying the effects of ultraviolet-B radiation on cotton growth and development. 32nd Biological Systems Simulation Work Group Symposium/Workshop on Remote Sensing and Modeling Applications for Natural Resource Management, 10-13 March 2002, Mississippi State, MS, USA. Vol. 32: p. 26.
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