1 - Interactive Effects of Water Stress and Elevated CO2 on Growth, Photosynthesis, and Water Use Efficiency

Abstract

This chapter focuses on three critical aspects of crop productivity as affected by water deficit and elevated CO2. Water deficit is probably the most important to determine plant growth and productivity worldwide. At the same time, climatic conditions and CO2 concentration in the atmosphere strongly influence plant water use and growth. Interestingly, as the level of CO2 rises above the present ambient level, photosynthesis enhances and transpiration often reduces, resulting in a higher efficiency of water use, while plant growth and productivity generally increase. Limited data also show that elevated levels of CO2 may facilitate plants' adjustment to drought. How water deficits and elevated CO2 interact to impact plant productivity and water use efficiency (WUE) is a pivotal question in terms of future changes of natural and managed terrestrial ecosystems. For natural communities, differences in WUE under elevated CO2 may determine the success in adaptation and competition of plant species, and ultimately in community succession, and in generally warmer temperature and more frequent drought.