Relative Water Content (RWC) Relative Water Content (RWC) is the appropriate measure of plant water status in terms of the physiological consequence of cellular water deficit. While water potential as an estimate of plant water status is useful in dealing with water transport in the soil-plant-atmosphere continuum, it does not account for osmotic adjustment (OA). Osmotic Adjustment is a powerful mechanism of conserving cellular hydration under drought stress and RWC expresses the effect of OA in this respect. Hence, RWC is an appropriate estimate of plant water status in terms of cellular hydration under the possible effect of both leaf water potential and OA. [20]. As observed by [96], the photosynthetic rate was strongly influenced by RWC of the leaf in papaya cultivars. When RWC declined to 80 per cent, the reduction in photosynthesis was more than 50 per cent. Slatyer [1955] also reported that a reduction by 5 per cent in RWC led to reduction in photosynthesis by 40-60 per cent in crop plants. In Theobroma cocoa, Mohd Razi et al. (1992) observed a significant reduction in both photosynthesis and transpiration as a result of drop in leaf water potential below 2.0 MPa. Drought resistance varieties showed consistently higher leaf water potential in their tissues than susceptible types under soil moisture deficit [132]. Plants under severe drought conditions had a small but significant decrease in RWC of leaves and a higher decrease in gas exchange parameters in legumes [116]. Maintenance of higher water status under drought plays a central role in stabilizing the various plant processes and yield. The solute potential (ψs) of the plants decrease under water stress and was accompanied by change in relative water content indicating a higher or lower osmoregulation depending upon the magnitude of the decrease. The decreased RWC under stress may be due to decreased leaf water potential (ψw) and decreased availability/absorption and translocation of water from soil to roots and ultimately to leaves. Retention of more water in leaf is known to be important to drought tolerance [127; 65]. Moisture stress is reported to cause decrease in water potential and RWC (185; 118). Reddy and Vora (1986) found significant decrease in RWC under moisture stress; this might be due to decrease in internal water content of protoplasm and loss of chlorophyll a : b ratio which might be the result of premature senescence of leaves.