मुख्य तथ्य

• PAR range: 400–700 nm — visible light that drives photosynthesis
• Blue light (400–500 nm): promotes compact vegetative growth and chlorophyll synthesis
• Red light (600–700 nm): drives photosynthesis most efficiently; promotes flowering
• Green light (500–600 nm): partially absorbed by plants; penetrates deeper into canopy
• Far-red (700–800 nm): not classic PAR, but triggers shade avoidance and the Emerson effect
• Lux and lumens measure light as perceived by the human eye — irrelevant for plant growth