ABSTRACT
This chapter explores the major effects of drought stress on critical steps that govern carbohydrate supplies and partitioning in plants and emphasizes the most recent advances in the field. It presents evidence on cellular and molecular mechanisms that are known to be manifested in physiological responses. Metabolic alterations or adjustments are interpreted to be an important adaptive mechanism for plants to survive the unpredictable nature of water availability under natural environments. The limited photoassimilates produced in leaves are utilized to support two mutually exclusive but crucial processes: assimilate export out of leaves for continued growth, development, and storage, or osmotic adjustment within the leaves. Depending on the growth stage of the plant, the limited photosynthates produced in source leaves under drought conditions may be utilized to support simultaneously export out of leaves and/or osmotic adjustment within the leaves. Low water potential may decrease sink activity by inhibiting expansion growth or assimilate metabolism and utilization in plants.
