2019 ASHS Annual Conference

Taro has historically been grown under flooded paddy conditions, however production has moved towards irrigated upland production. Under upland growing conditions taro has shown to respond positively to increased irrigation. To better understand the relationship of irrigation on components of plant growth, three taro cultivars (‘Bun long’, ‘Lehua’ and ‘Pi‘i‘ali‘I’) were irrigated based on reference evapotranspiration (ET₀) and soil moisture. Irrigation treatments consisted of 100%, and 200% ET₀ replaced calculated using a modified Hargreaves Model and 100% and 200% of field capacity (FC) maintained by an Irrometer tensiometer sensor attached to an automatic irrigation timer. Irrigation rates significantly affected all growth characteristics, with the greatest differences between plants receiving 100-200% ET₀ replaced and plants maintaining 100-200% FC. On average, plants maintaining 100% and 200% of FC were heavier, taller and produced more cormels than plants receiving 100% and 200% ET₀ replaced, across all three cultivars. Plants maintaining 200% FC received the largest quantity of water and showed significantly greater yields than all other treatments. Plants receiving 200% ET₀ replaced received the second highest quantity of water, however produced significantly lower yields than plants receiving less water at 100% FC maintained. In addition, the potential to estimate corm weight based on its relationship to percent ET₀ replaced and percent field capacity maintained can assist in crop modeling and irrigation scheduling to maximize water use efficiency of taro. These models can also help to estimate cost benefit analysis, which can be used to determine the quantity of water needed to maximize yield and profits.