Nutrient and Water Constraints to Anthurium Productivity In East Hawaii

The Hawaiian anthurium industry is primarily located in East Hawaii. There, low cost volcanic cinder media, abundant moisture and uniform temperatures created a large export industry which has now been eclipsed by other producers. A long term trial was conducted with local nurseries to determine how water and nutrient management limit anthurium yield, flower quality and unit production costs.  Despite high rainfall (>200 cm/y) and concomitant low light environments, anthurium yields were limited by water availability and phosphorus supply. Under rainfed conditions with standard slow release fertilizer application additional daily pulse irrigation increased total flower yield by 13% and large flower yield by 21%. When P availability was increased in the standard nutrient management regime or plants were pulse fertigated (1120uS) yields rose by 24% and 25% respectively and large flower yields increased by 35% and 48% respectively. Analysis of leaves sub-tending mature flowers indicated yield and flower size increased when leaf P was raised above the current Hawaii recommendation of 0.17%. Irrigation trials under cover showed fertigation multiple times each day  is required to maximize anthurium yield grown in 15 L containers of volcanic cinder. Flower yields increased consistently with fertigation frequency. Compared to single daily fertigation, total and large flower yields increased by 20% and 30% respectively when plants were fertigated six times per day. The yield response to fertigation frequency is not due to lack of total moisture retained in the cinder medium.  The container volumetric water holding capacity was 3300 mL (22% by volume) while potential plant uptake from the container averaged only 200 mL/d. It is our contention that two factors limit water and concomitantly nutrient availability to anthurium grown with volcanic cinder.  First, the coarse root structure of the plant exploits only a small faction of the container volume and secondly, the poor capillarity of the cinder is inadequate to maintain sufficient water and nutrient flux to the root surface.  A partial budget analysis of fertigation management options demonstrated a large and increasing return to greater fertigation frequency despite leaching fractions of over 80%. If Hawaiian anthurium growers are to maintain a competitive position in world markets it is imperative growers increase yield and flower quality through a variety of means, including better water and nutrient management.

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