This study investigates changes in the stomatal diffusive resistance, free proline level, and total chlorophyll in clones IAC 222 , IAN 717, IAN 873 and IAN 6485 of Young rubber trees evaluating their drought resistance by measuring these parameters during fifty days οf drought.
Water deficit prevention was determined by stomatal resistance; and tolerance was measured by the accumulation of free proline. The effect οf water deficit on total chlorophyll level was also ascertained.
Clone IAN 873 showed the highest stomatal diffusive resistance and free proline level; whereas, total chlorophyll decreased with water deficit.
Clone IAN 717 showed low stomatal diffusive resistance and free proline level, but maintained a high level οf chlorophyll during almost the whole experimental period.
The results suggest that the free proline level reflects tissue hydration rather than drought resistance in rubber trees. Clone IAN 873 suffered highest dehydration. Clone IAN 717 mantained more hydrated tissues and was thus the most resistant.