Abstract

A study was conducted in 1992-95 to investigate the environmental constraints to optimum physiological performance of the newly introduced oil palm (Elaeis guineensis) at a site in each of Andhra Pradesh, Karnataka and Maharashtra, India. Temperatureat the study sites ranged from 12 to 35°C. Minimum temperatures in Karnataka and Maharashtra were much lower than those in areas considered suitable for growing oil palm. Vapour pressure deficit (VPD) at the 3 sites ranged from 0.3 to 4.5 kPa and the photon flux density was not limiting at any site. Light saturation of photosynthesis was achieved at _1000 µmol m-2s-1 and the maximum stomatal conductance of oil palms was 500 mmol m-2s-1. The maximum photosynthetic rate ranged between 7.5 and 11.5 µmol m-2s-1, which was intermediate compared to reported values from other oil palm growing countries. Stomatal closure was observed when VPD increased from 1.0 kPa, and stomatal conductance was severely reduced when VPD reached _1.9 kPa. Predawn water potentials indicated that the plants were not water stressed during the study period, but all sites had a prolonged dry season that created large water deficits, thus oil palm could not be grown as a rainfed crop. Water loss by transpiration on a dry day was high, ranging from 2.0 to _5.5 mm/day, which was attributed to the unstressed condition of the plants due to irrigation. At all 3 sites, leaf number increased by approximately 2 per month and leaf area increased by 5-11 m2/month. However, the leaf area increase was much lower than that of similar plants in Malaysia. Recommendations for mitigating environmental constraints are given