Physiological features and growth characters of oil palm (Elaeis guineensis Jacq

Optimum irrigation is very important for nursery stock management of F1-hybrid oil palm (Elaeis guineensis Jacq.), constituting a major production cost. Generally, over watering of nursery stock can be a cause of loss of productivity. The aim of this study was to investigate the physiological and biochemical responses of oil palm nursery stock to reduced soil water content (SWC) and during the recovery process. Water deficit treatments, full-irrigation (control; 54% SWC), 4-days withholding irrigation (42% SWC), 8-days withholding irrigation (20% SWC), 12-days withholding irrigation (13% SWC) and 16-days withholding irrigation (6% SWC) were applied uniformly to the oil palm plants. Proline content and relative electrolyte leakage (REL) in the leaf tissues increased, relative to a degree of reduced SWC, especially in ≤20% SWC water deficit stress. Oil palm nursery stock was sensitive to severe water deficit (6-13% SWC), which was identified by physiological changes and growth inhibition and those parameters failed to recover in the re-watering process. During recovery, proline content and REL in extreme water deficit conditions were still enriched, resulting in greater photosynthetic degradation, diminution of chlorophyll fluorescence, reduction of net photosynthetic rate (Pn), and growth retardation. The wilting point of nursery stock oil palm was defined as 20% SWC, below which plants recovered by watering, without toxic symptoms. The study provides useful information for developing irrigation systems for oil palm, especially F1 hybrid nursery stock.