ASHS 2024 Conference

The growing of taro in aquaponic systems has yielded corms significantly smaller than those grown terrestrially. Previous trials only partially supported the hypothesis that these low yields were due to excessive water and nitrogen levels late in vegetative development. A 2×2 (nitrogen restricted × supplemental fertilizer) factorial designed experiment was replicated 4 times in dual-tub systems. The 4 treatments tested were: 1) Fish effluent supplied throughout 10 months of plant development (T1); 2) Fish effluent restricted from the system at 6 months and fresh water supplied for the remaining 4 months of development (T2); 3) T1 plus supplemental potassium and iron fertilizer (T3); 4) Treatment 2 plus supplemental potassium and iron fertilizer (T4). The results indicate that the supplemental fertilizer was more important than effluent restriction late in development in enhancing corm growth, although effluent restriction did result in a higher maturity index of corms under supplemental fertilizer treatment. The corm yields were 140% higher in T3 (1.5 kg plant-1) than in T2 (0.63 kg plant-1). T4 had significantly more biomass partitioned into the corm (56% of total biomass) compared to T3 (44% of total biomass). The ratio of corm: total biomass is a key indicator of plant maturity and suggests restriction of high nitrogen effluent enhanced photosynthate translocation to the corm under supplemental fertilizer. Corm density was highest in T3 and lowest in T4, perhaps due to starch conversion to sugar in over-mature corms in T4. These results demonstrate the importance of supplementing potassium and iron fertilization, as well as restricting high nitrogen fish effluent late in taro corm development, to optimize taro yields and quality in aquaponic production systems.