Relative water content (RWC) in the flag leaf of PT1 (lowland irrigated cultivar) and
IR20 (negative check) rice cultivars (water-deficit susceptible) dropped significantly in
plants exposed to mild water-deficit with 25% soil water content (SWC) and RWC
recovery was delayed during re-watering. The RWC in both KDML105 (moderately
water-deficit tolerant) and NSG19 (positive check) was maintained in mild water-deficit
but decreased significantly when plants were exposed to severe water shortage (7%
SWC) (Table 1) and increased quickly after re-watering. A positive correlation between
SWC and RWC was demonstrated in each cultivar (Fig. 1). The gradient of the SWC and
RWC relationship in the water-deficit susceptible cultivars IR20 and PT1 was greater
than that of the water-deficit tolerant cultivars, NSG19 and KDML105. It should be noted
that the reduction of RWC was progressively related to SWC, especially in the waterdeficit
sensitive cultivars (Fig 1B and 1D)