Response of nutritional water productivity in okra (Abelmoschus esculentus) seeds to irrigation interval

Nutritional water productivity (NWP), which quantifies nutrition in produce per volume of water, is an approach for providing empirical information on incidents of malnutrition as affected by various cultural practices in crop production. The objective of this study was to investigate the effects of irrigation interval on NWP in okra seeds under warm-arid regions. Hardened-off okra seedlings were transplanted under field conditions and subjected to 2-, 4-, 6-, 8-, 10-, 12- and 14-day irrigation interval, with 2 000 ml tapwater/seedling. At 59 days after transplanting, pods were harvested and pods shelled, with seed samples prepared for NWP-related tests. Pods were dried at 60℃ for 72 h for dry matter determination. Irrigation interval had highly significant effects on yield, evapotranspiration (ETa) and water use efficiency (WUE), contributing 75, 96 and 87% in total treatment variation of the respective variables. Relative to Day-2, yield and WUE were significantly higher on Day-8, but were not significantly different to those in Day-14. However, ETa was significantly higher on Day-2 than in all other irrigation intervals. Irrigation interval had highly significant effects on NWP of Ca, K, Mag, P, Cu, Fe, Mn, Na and Zn, contributing from 84 to 89% in total treatment variation on the respective variables. Relative to Day-2, Day-8 NWP variables were significantly higher than those at lower or higher irrigation intervals, where NWP values were significantly reduced. In conclusion, results in the current study suggested that Day-8 irrigation interval was suitable for improving NWP of okra under existing conditions.