Abstract:
This study was conducted to determine the gas exchange rates and water use efficiency of young
oil palm, rubber and tea plants under different soil moisture regimes. All the plants were grown
in poly bags in which the size was determined according to the planting density of respective
crops. Another set of rubber plants were planted in the bag size recommended for nursery
plants. Plants were grown under greenhouse conditions and half the number of plants were
provided with adequate irrigation whilst the other plants were watered to the field capacity only
at the commencement of study. In watered condition, photosynthetic rate was similar in both
rubber and oil palm. It was significantly low in tea. The decline in photosynthetic rates due to
moisture stress was relatively high in oil palm and tea when comparing to rubber. Canopy
photosynthesis was high in Oil palm because of the high leaf area per palm. Water use efficiency
was maintained with increasing moisture stress condition by oil palm and rubber crops. Tea
succumbs to moisture stress much earlier than the other crops tested in this study.
