2017 ASHS Annual Conference

In recent years, commercial, institutional and subsistence aquaponic systems have become increasingly popular in Hawai'i. A series of 4 variety trials were conducted during the period 2012-2017 to evaluate yield and quality of aquaponically grown pak choi, and determine which varieties are well suited for aquaponic production. In each trial, plants were seeded in trays and 3-week old seedlings transplanted in cinder beds fed by tilapia (Oreochromis sp.) effluent at the Waimānalo Experiment Station. Trials were arranged in a randomized, complete block design with four replications per variety. Three heads per replication were harvested ~28 days after transplanting and evaluated for multiple traits including marketable fresh weight and total glucosinolate concentration. Across varieties, yield was 40% higher and glucosinolate concentrations 25% lower in winter- relative to summer-grown pak choi, presumably in response to higher summer air temperatures. Differences in fish density, water quality and plant nutrient status also likely contributed to the considerable variability observed in marketable yield. Among the high value green stem pak choi varieties, ‘Mei Qing’ and ‘Black Summer’ were consistently high yielders relative to other varieties. The range of yield (75 - 500g/plant) and glucosinolate concentrations (20-50 mmol/kg dry weight) observed in aquaponically grown pak choi are comparable with values reported for soil-grown pak choi. Understanding genotypic and environmental influences on the yield and quality of pak choi and other vegetables is expected to contribute to the overall success of aquaponic producers.