Effects of Water Stress on the Physiological Processes and Water Use Efficiency in Oil Palm

Malaysia is currently the major producer of palm oil in the world with a total production of crude palm oil of about 15 million tonnes in 2005. This major commercial crop in Malaysia covers an area of about 4 million hectares of agricultural land. Due to its important role, various research and development are still on going to improve and to ensure the sustainability of this industry. In this physiological study of oil palm, focus was given to two different environments and palm age. In the first experiment, physiological evaluation was done on two different planting materials namely the commercial DxP and PS1.1 dwarf palms. This PS1.1 planting material is expected to be shorter, higher yielding, more compact and with desirable fruit qualities. The seedlings were raised in large polybags filled with topsoil. Experiments were initially done at Green House I that was located near the UPM Hydroponics and later, at Green House II situated at the UPM Agriculture Park. Various physiological parameters were studied to compare the performance of both genotypes and their responses to soil drying. Four replicates of ten seedlings per treatment were used. Among the parameters studied were gas exchange, chlorophyll fluorescence, vegetative growth, chlorophyll content, root:shoot ratio, soil moisture and leaf sugar analysis. Based on vegetative measurements, DxP seedlings had 34% longer rachis length than PS1.1 and were 29% taller. The leaves of DxP seedlings had higher relative water content and moisture content as compared to PS1.1. As water is essential for cell growth, this may be one of the factors that enable the DxP seedlings to grow faster. The leaf chlorophyll content was slightly higher in the DxP as compared to PS1.1 seedlings. Fluctuations in leaf sugar contents were found in both genotypes in response to soil drying. DxP seedlings had significantly higher water use efficiency (WUE) (p