Effect of Irrigation Interval on Growth, Yield and Water use Efficiency of Okra (Abelmoschus esculentus L.) in Sandy Soil Under Dry Zone Conditions of Sri Lanka

Abstract

Efficient irrigation management is critical for improving crop productivity and water use efficiency, particularly in water-limited environments and sandy soil with low water holding capacity. This study evaluated the effects of different irrigation intervals on the growth, fruit yield and water use efficiency of okra (Abelmoschus escuentus) cultivar EUOK-2 under dry climatic conditions of Palacholai, Batticaloa, Sri Lanka. The experiment was conducted using a Randomised Complete Block Design with four irrigation treatments: T1 (twice daily-control) was selected based on the common irrigation practice adopted by farmers cultivating vegetables on sandy soils in the Palacholai area, T2 (irrigation once daily), T3 (irrigation based on the calculated intervals), and T4 (three days interval). Growth, yield and biomass parameters were assessed. Results showed that frequent irrigation significantly enhanced plant growth, biomass accumulation, yield, and WUE compared with longer irrigation intervals. The highest yield (16,050 kg ha⁻¹) was recorded under T1, while the longest irrigation interval (T4) resulted in the lowest growth and yield performance. Statistical analysis revealed significant differences (P < 0.05) between T1 and the other irrigation treatments in terms of growth, yield, and water use efficiency (WUE). Conversely, the longest irrigation interval (T4) resulted in substantially reduced growth, yield, and WUE. Although twice-daily irrigation improved yield and WUE, the practicality of this method under field conditions should be evaluated considering labour requirements and irrigation method.