Osmotic adjustment is defined as the net accumulation of solutes in tissue allowing the water potential to decline while maintaining turgor in response to water stress. The maintenance of turgor pressure is assumed to be essential for expansive growth and for other physiological processes. Solute concentration can increase in leaf tissue due to either passive or active accumulation processes.

The leaf water potential component responses of cotton to water deficits have been investigated by several workers. Cutler and Rains (1977) have reported maintenance of leaf conductance and expansive growth due to solute-accumulation in adapted plants. Ackerson et al (1981) also reported osmoregulation in adapted cotton when subjected to a series of water stress. Quisenberry et al (1984) found negative relation between solute accumulation at full turgor and shoot dry weight. At present the question of whether osmotic adjustment is truly an adaptation resulting in benefits to the plant or whether it is merely a symptom of stress reducing assimilate utilization to a greater extent than its production has not been resolved. The objectives of this experiment were (1) to determine the cause of osmotic adjustment and (2) the effect of osmotic adjustment on physiological processes and productivity of cotton.