1. The review frequently promotes red and blue light combinations as universally optimal for photosynthesis and morphogenesis. However, spectral optimization is highly species-specific and even cultivar-dependent, especially in C3 vs. C4 plants or photoperiod-sensitive species. How do the authors account for the physiological trade-offs between spectral efficacy (e.g., PPFD vs. YPF) and photomorphogenic signaling (e.g., cryptochrome or phytochrome activation) across diverse horticultural crops? Shouldn’t the review have critically addressed the limitations of generalizing optimal spectra across crop systems and development stages?
2. The discussion emphasizes energy-efficient outcomes of LED lighting but largely interprets this from a photon output perspective. Did the authors consider distinguishing between quantum efficiency (photons per joule) and energy use efficiency (grams of biomass per kilowatt-hour) in the context of real greenhouse operations? In high-input systems, especially in cold climates where HPS can contribute to thermal loads, the assumption that higher photon efficacy directly equates to better system-level energy efficiency may not hold. Shouldn’t this distinction have been discussed in more depth when advocating for LED dominance?
I would raise another concern: while the paper performs a broad bibliometric analysis, it does not explore how research themes in greenhouse lighting have evolved over time. For instance, recent trends toward using dynamic lighting strategies, far-red enrichment, and targeting secondary metabolism are not clearly captured. A more detailed temporal or thematic trend analysis would have provided deeper insight into the shifting priorities in this rapidly advancing field.