Effects of carbon dioxide, temperature and ultraviolet-B radiation and their interactions on soybean (Glycine max L.) growth and development

Genetic modifications of agronomic crops will likely be necessary to cope with global climate change. Projected changes in global climate nclude increasing atmospheric carbon dioxide concentration ([CO2]), temperatures (T) and ultraviolet-B (UV-B) radiation which have significant ffects on plants, however, their interactions are not clearly known to date. In this study we tested the hypothesis that soybean genotypes differ in rowth and physiology with exposure to treatments of [CO2] [360 and 720 mol mol−1 (+[CO2])], temperature [30/22 and 38/30 ◦C (+T)] and UV-B adiation [0 and 10 kJ m−2 d−1 (+UV-B)] and their interactions. Six soybean genotypes (D 88-5320, D 90-9216, Stalwart III, PI 471938, DG 5630 R, and DP 4933 RR) representing five maturity groups were grown in eight sunlit, controlled environment chambers in which control treatment ad 360 mol mol−1 [CO2] at 30/22 ◦C temperatures and 0 kJ UV-B. Results showed that elevated CO2 levels compensated the damaging effects aused by negative stressors such as high temperature and high UV-B radiation levels on most of the growth and physiological parameters studied. otal stress response index (TSRI) for each genotype was developed from the cumulative sum of response indices of vegetative and physiological arameters such as plant height, leaf area, total biomass, net photosynthesis, total chlorophyll content, phenolic content, relative injury and wax ontent. Based on TSRI, the genotypes were classified as tolerant (PI 471938 and D 88-5320), intermediate (DG 5630 RR and D 90-9216) and ensitive (DP 4933 RR and Stalwart III). The disruption of growth and physiology was significantly reduced in tolerant genotypes compared to ensitive genotypes. Strong correlations between total response of relative injury (RI), an indicator of cell membrane thermo stability and TSRI eveloped in this study show that RI could be used to predict the overall vegetative performance of the crop. However, the total response of RI id not show any linear correlation with TSRI of our previous study (which was developed with responses of reproductive traits). This suggests hat there is a need to develop better screening tools and/or breeding strategies in developing genotypes suitable to cope future climates at both egetative and reproductive stages. 2006 Elsevier B.V. All rights reserved.