The 2011 ASHS Annual Conference

To better understand the relationship of irrigation regimes on components of plant growth and quality, three taro cultivars (‘Bun long’, ‘Lehua’ and Pa’akala’) were irrigated based on reference evapotranspiration (ET₀) replaced. Irrigation treatments consisted of 50%, 100%, 150%, 200% and 250% of ET₀ replaced. Irrigation rates significantly affected all growth characteristics, with the greatest differences between 50%-100% and 150%-250% ET₀ replaced. On average plants receiving 150%-250% ET₀ were heavier, with larger leaf area and more cormels than plants receiving 50%-100% ET₀. Plants that received 150% ET₀ showed no significant differences than treatments receiving larger amounts of water. A positive quadratic relationship (r² = 0.94-0.99) for each cultivar was found between dry weight and percent ET₀ replaced. Across cultivars, no significant relationships were found between irrigation and components of quality. Supplying irrigation at 150% ET₀ replaced is sufficient in maximizing yield of ‘Bun long’ and ‘Pa’akala’. However, replacing irrigation up to 250% ET₀ to a lowland cultivar such as ‘Lehua’ did not result in yields comparable to flooded systems. In addition, the potential to predict corm weight based on its relationship to percent ET₀ replaced can assist in crop modeling and irrigation scheduling for maximizing water use efficiency. These models can also help to estimate cost benefit analysis, which is important for determining whether the increase in yield is worth the increase in water cost.