STRESS DEVELOPMENT AND ITS DETECTION IN YOUNG OIL PALMS IN NORTH KEDAH, MALAYSIA

摘要

Various methods of detecting and quantifying stress in'oil palm are briefly reviewed. Stress is defined loosely as any environmental condition leading to reduced productivity and loss of yield. Common environmental stresses include those induced by water deficit, water logging, low atmospheric humidity, high temperatures, nutrient deficiency and low radiation. Different stress-inducing factors are frequently combined; e.g. water deficit and high temperature stress, water deficit and nutrient stress; high temperature and low atmospheric humidity stress. Results are presented of measurements made on young field palms planted in a dry region in north Kedah, Malaysia. The measurement period spanned wet and dry seasons. Short-term stress responses evaluated were: ⅰ) changes in canopy surface temperatures relative to air temperatures, ⅱ) changes in spear leaf extension rates, and ⅲ) changes in the ratio of actual to potential evapotranspiration. The responses are related to soil water supply, solar radiation, atmospheric vapour pressure deficit and potential evapotranspiration rate. The potential for using canopy surface-air temperature difference (ΔT) and spear leaf extension measurements as a means to monitor irrigation need is discussed.