Split-root Nutrition of Sweetpotato in Hydroponic Systems

Nutrient film technique (NFl) and deep water culture (DWC) hydroponic systems were used in a split-root study of the effect of four treatments on sweetpotato yield, the translocation of assimilates, and microbial population count. 'TU-155' cuttings (15 cm) were prerooted for 30 days in sand using deionized water and a modified half-Hoagland (MHH) solution. After 30 days, the plants were removed, and the roots of each were cleaned and split evenly between two sides of a channel (each 15 cm deep by 15 cm wide by 1.2 m long), four plants per channel. Replicated treatments were: MHH/MHH; MHH/Air, MHH/deionized water (DIW); and monovalent/divalent anions and cations (Mono/Dival). The entire experiment was repeated. Plants were harvested after growing for 120 days in a glasshouse. Storage roots, when produced, were similar in nutritive components. However, no storage roots were produced in Air or Mono channels and only a few in DIW suggesting inhibition of assimilate translocation. Fresh and dry weights for storage roots and foliage were highest in MHH/MHH in both Nfl and DWC in both experiments. Solution samples were collected at 14-day intervals for microbial population profiling. Microbial counts (4.20-7.49 log cfulml) were highest in Dival channels. The counts indicated that solution composition influenced population size, and they were relatively high in both systems.