Influence of LED spectral quality and natural growing conditions on flowering, yield, and fruit biochemical quality of okra (Abelmoschus esculentus (L.) Moench)

Introduction Climate change poses significant challenges to open-field production of okra ( Abelmoschus esculentus (L.) Moench), a tropical vegetable crop of high nutritional and economic value. This study evaluated the effects of light-emitting diode (LED) spectral quality on reproductive development, fruit characteristics, yield, mineral composition, antioxidant activity, and total phenolic content of okra. Methods Plants were grown under blue (452 nm), red (659 nm), and combined red/blue (9:1; 657/447 nm) LED lighting at a photosynthetic photon flux density (PPFD) of 400 µmol m −2 s −1 under a 10-h photoperiod and compared with greenhouse and outdoor conditions. Results The red/blue 9:1 (RB 9:1) treatment promoted earlier flowering, with anthesis occurring approximately 37 days after sowing, and showed the highest numerical fruit length and fresh fruit mass, as well as the highest yield per plant and estimated yield per hectare, the latter being approximately twice that of the other growing conditions. RB 9:1 showed the highest numerical concentrations of calcium, potassium, sulfur, copper, and zinc, while outdoor plants showed the highest numerical concentrations of iron and strontium and red light the highest numerical rubidium concentration. RB 9:1 showed the highest numerical antioxidant activity, although it was not significantly different from red or blue light. Blue light showed the highest numerical total phenolic content, with no significant differences among treatments. Discussion Overall, RB 9:1 showed promising potential for earlier reproductive development and fruit production under the tested conditions.