Researchers at Humboldt-Universität zu Berlin applied DC current at 8V and 16V (10 h/day, 12 days) via stainless steel plate electrodes to Solanum scabrum Mill. (African nightshade) plants in a greenhouse setting. The study assessed yield quantity, yield quality (marketable vs. non-marketable), photosynthetic pigments, cell-wall components, mineral content, and heavy metal accumulation.
The most commercially significant finding was the dramatic redistribution of leaf quality: marketable leaf count rose +55.3% at 8V and +29.1% at 16V, while non-marketable leaves dropped -77.2% and -64.9% respectively. Leaf fresh weight increased at both voltages (+11.5% and +14.4%), and leaf dry weight rose +24.2% at 16V — indicating both more biomass and better dry-matter concentration.
Mineral content showed strong electroosmotic effects: leaf calcium rose +27.5% at 16V, and stem zinc increased +244.4% at 16V — an extraordinary enrichment likely reflecting ion migration driven by the electric field. Magnesium in stems rose +15.6% at 16V. Heavy metals were elevated but remained within EFSA safety thresholds.
Pigment response was biphasic: 8V reduced chlorophyll and carotenoid content relative to control (~15%), while 16V restored and slightly exceeded control levels. Stem carotenoids showed the strongest enrichment at 16V (lutein +20%, β-carotene +30%). Hemicellulose increased substantially in both leaves (16V: +40%) and stems (8V: +52%), suggesting DC-stimulated cell-wall reinforcement that may improve postharvest shelf life.
Vault reference: [[Paper - Gogo - DC Effects on African Nightshade 2016]] in the Energetic Agriculture vault.