Plant - Microbe Interactions and Water Management in Arid and Saline Soils

Drought and salinity are major factors limiting agriculture in many regions in the world, and their importance is predicted to even increase in the near future in parallel with the ongoing global warming and climate changes. Soil and rhizosphere microbes are potential resources for counteracting such abiotic stresses in plants. The knowledge on the roles of root microorganisms in retaining soil humidity and promoting plant growth under such abiotic stresses is analyzed in this chapter. The importance of microbial diversity in the rhizosphere for alleviating drought and salinity effects on the plant physiology is discussed in the light of “Desert Farming”, the general crop management practice that is frequently used in arid regions. The plant growth promoting functional services exerted by microorganisms within the rhizosphere in arid soils are presented in relation to the plant response under water stress. 26.1 The Effects of Drought and Salinity on Plant Physiology A major challenge for future agriculture is to cope with the increasing demand for food production, facing a constantly increasing world population. This growing demand for agricultural production is paralleled by dramatic losses of arable land due to enhanced soil destruction and erosion. Drought and soil salinity are the two major environmental factors that limit plant growth and development thereby negatively affecting agricultural yield by more than 60%. Water shortage is critical in many areas of the world and is usually countered by extensive irrigation. Although the planet earth is rich in water, not only the water of the oceans, but also most inland water resources are highly saline. Moreover, irrigation usually results in soil salinization making drought and soil salinity increasing agricultural problems (Bartels and Sunkar 2005). To convert deserts into arable, green landscape is a global vision as well as competent answer to world hunger and climate change (Clery 2011). Desert farming, which generally relies on irrigation, is part of this vision. Agriculture systems were already developed in arid