Effect of Molybdenum on the Chlorophyll Fluorescence Parameters, Growth and Quality of Cherry Radish in Hydroponics

Molybdenum (Mo) is considered an essential element for plants, whose functions are related to nitrogen metabolism. Compared with other trace elements, the agronomic characteristics of Mo application in cherry radish production have not been described. In this study, we investigated the effects of different Mo concentrations on the chlorophyll fluorescence parameters, growth and quality of cherry radish, as well as photosynthesis-related parameters. Cherry radish seedlings were transplanted and exposed to Mo concentrations of 10, 20, 30 and 40 μg·L−1 as (NH4)6Mo7O24·4H2O, with no added Mo serving as CK in hydroponics. The impacts of Mo on plant growth, photosynthesis-related parameters, nitrate content, and other quality parameters were analyzed. The results showed that the Mo application significantly improved the growth and most quality parameters of cherry radish. Notably, when Mo was applied at 30 μg L−1 (M3), most measured parameters of cherry radish were significantly increased, including fresh weight, maximum leaf area, chlorophyll fluorescence parameters, soluble sugar and soluble protein content. Additionally, the Mo application effectively reduced the nitrate content in cherry radish. Under the M3 condition, nitrate accumulation in leaves and fruits was minimized, with reductions of 42.12% and 37.35%, respectively, compared with the CK. Furthermore, we found that the fresh weight and most quality parameters of cherry radish showed significant correlations with the applied Mo. These results suggest that the application of Mo could increase the yield and quality of cherry radish and reduce the accumulation of nitrate in leaves and fruits of cherry radish, which could bring agricultural, environmental and economic benefits.