Nutrient solution electrical conductivity regulates biomass production, fertigation consumption, and nitrate accumulation in lemon basil ( Ocimum × citriodorum ) microgreens

Optimizing nutrient solution electrical conductivity (EC) is essential for balancing nutrient availability, water uptake and biomass production in soilless microgreen cultivation. However, information on the nutritional requirements of lemon basil (Ocimum × citriodorum) during the microgreen stage remains limited. This study evaluated the effects of four nutrient solution EC levels (1.00, 2.20, 2.75 and 3.10 dS m−1) on fertigation consumption, biomass production and nitrate accumulation in lemon basil microgreens grown under controlled-environment conditions. Nutrient solution EC affected both fertigation consumption and biomass production. The highest fertigation consumption was recorded at the lowest and highest EC levels, whereas an EC of 2.20 dS m−1 resulted in the highest fresh and dry biomass production, with increases of 13% and 42%, respectively, compared with the other EC treatments. Nitrate concentration in the shoots increased linearly with increasing EC (R2 = 0.969), indicating a strong association between nutrient solution concentration and nitrate accumulation in edible tissues. Under the experimental conditions tested, an EC of 2.20 dS m−1 provided the most favorable balance between fertigation consumption and biomass production. These results highlight the importance of optimizing nutrient solution EC for efficient nutrient and water management in lemon basil microgreens and provide a basis for further research on nutrient uptake and nitrogen metabolism under different nutrient solution regimes.