Photosynthesis and Abiotic Stresses

The global environment is changing with changes especially driven by increasing temperature and CO2 (IPCC, 2001). These key variables affect plant growth, development and function, starting with photosynthesis, the most important process in the plant world, sustaining life on earth (Drake et al., 1997). Photosynthesis is an ancient process and it has adapted in the past to different life conditions and environmental changes. On the other hand, photosynthesis is very sensitive to the environment, immediately sensing minimal environmental changes and triggering a series of adjustments eventually leading to adaptation through changes of primary production. Nowadays, the world is undergoing a series of “novel” environmental changes predominantly caused by anthropogenic activities (IPCC, 2001). Whether these factors, alone or in combination with independent changes of environment, will positively or negatively affect photosynthesis, and will trigger the onset of adaptive responses on photosynthesis (Long et al., 2004), remains to be determined. The effects of global changes on photosynthesis can be extremely complex, reflecting the natural plant biodiversity but also the microclimate diversity. The world’s terrestrial ecosystems constitute a continuum from virtually pristine to intensively managed and highly modified systems devoted to production.