In cellular respiration, glycolysis is the first step in which glucose is oxidized into pyruvate. The electrons released by glucose during its oxidation is taken by NAD⁺ which gets reduced to NADH in glycolysis.
This NADH then again get oxidized by transferring the electron to oxygen through an electron transport chain present in mitochondria. This electron transfer is necessary for ATP generation for cell and regeneration of NAD⁺ that can again be used in glycolysis.
So when a chemical used that prevents NADH from being oxidized then no electron will be transferred to oxygen so oxygen will not be consumed and no ATP will be generated and also no NAD⁺ will be available for glycolysis.
Therefore all the metabolic process will stop and no consumption of oxygen will occur which will lead to the death of the seedling.