Lettuce grown under recycled hydroponics ensures efficient water and nutrient utilization. However, lettuce yield often declines in successive cultures due to the accumulation of phytotoxic root exudates. Degrading these toxic exudates with a titanium-based electrode and increasing photosynthetic efficiency by adding green light can improve lettuce yield. Alternate current electro-degradation (AC-ED) was applied along with the addition of green light in the light spectrum to enhance lettuce yield. Lettuce seedlings were grown in a plant factory using half-strength Enshi solution. Three consecutive cultures were performed under three combinations of LEDs [Red (R):Green (G):Blue (B) viz. 235:00:59, 211:30:53, and 187:60:47 μmol m⁻² s⁻¹] using renewed (RW), non-renewed (NR), and AC-ED applied non-renewed (NR+AC-ED) nutrient solutions.
Results showed that in subsequent cultures, lettuce yield declined in the NR solution under 187:60:47 of R:G:B. In contrast, NR+AC-ED solutions showed maximum lettuce growth and enhanced yield by about 30% under the addition of 30 μmol m⁻² s⁻¹ of green light. However, the addition of 60 μmol m⁻² s⁻¹ of green light resulted in lower yield under all nutrient solutions. The nutritional quality of lettuce was not affected by nutrient solutions and LEDs. Our study recommends applying AC-ED for reutilizing fertigation water and the addition of 30 μmol m⁻² s⁻¹ green light for higher lettuce yield under successive cultivation.
Razzak, Md & Asaduzzaman, Md & Asao, Toshiki. (2025). Titanium based electro-degradation of nutrient solution and green light improve autotoxicity, growth and yield of lettuce grown in recycled hydroponics. Advances in Horticultural Science. 38. 393-405. 10.36253/ahsc-16177.
Source: Research Gate